Note: Descriptions are shown in the official language in which they were submitted.
CA 03107975 2021-01-28
Description
ELECTRIC LOADING MULTIFUNCTIONAL TEST BENCH FOR POWER-DIVIDING
HYDRAULIC-MECHANICAL COMPOSITE TRANSMISSION SYSTEM AND APPLICATION
THEREOF
I. Technical Field
The present invention relates to an electric loading multifunctional test
bench for power dividing
hydraulic-mechanical composite transmission system and application thereof,
which are suitable for
acquisition of performance parameters of a hydraulic transmission unit and
testing of the proportion
of mechanical power flow and hydraulic power flow of a transmission system,
and belong to the
technical field of engineering machinery.
II. Background Art
Engineering machinery, tractors and other working vehicles have
characteristics of high
transmission power, complex operating conditions and wide speed regulation
range. With the
development of the society and the continuous progress of technology, the
requirements for
transmission efficiency, shifting comfort and operation automation level of
the transmission systems
thereof become higher and higher. Hydraulic-mechanical continuously variable
transmission (CVT)
is a type of power dividing hydraulic-mechanical composite transmission that
combines hydraulic
power flow and mechanical power flow for power transmission. It can realize
high-efficiency
high-power transmission by means of mechanical transmission as well as realize
variable
transmission by means of hydraulic transmission, and exhibits good application
prospects on
high-power vehicles. The hydraulic-mechanical CVT combines the advantages of
excellent stepless
speed regulation performance of hydrostatic transmission and high steady-state
efficiency of
mechanical transmission, so as to obtain a variable speed transmission device
with stepless speed
change ability, high efficiency and favorable distribution of high-efficiency
area. Therefore,
designing and developing high-performance hydraulic-mechanical CVTs for
hydraulic-mechanical
composite transmission system is the key to the technical research and
application of high-power
vehicles.
A hydraulic-mechanical CVT comprises a mechanical transmission unit, a pump-
motor hydraulic
continuously variable transmission unit, a planetary gear mechanism for
dividing or converging
power, automatic speed changing electronic control device, and a driving
system, etc. When the
transmission ratio of the mechanical transmission mechanism is given, the
transmission ratio of the
hydraulic-mechanical composite transmission system can be changed steplessly
within a certain
range by adjusting the transmission ratio of the hydraulic continuously
variable unit, so that the
power is outputted through power dividing, stepless speed change and
convergence, and thereby
high-power high-efficiency continuously variable transmission is realized.
Therefore, such a power
dividing hydraulic-mechanical composite transmission system integrates the
advantages of high
transmission efficiency of a pure mechanical transmission system and stepless
speed change of a
pure hydraulic transmission system. However, the overall efficiency of the
transmission system is
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determined by the efficiency of the fractional hydraulic power flow and
efficiency of the fractional
mechanical power flow in composite transmission and their allocation ratio.
The transmission
efficiency characteristics of the mechanical transmission unit are relatively
stable, while the
transmission efficiency of the hydrostatic transmission unit is lower than
that of mechanical
transmission. The hydraulic pump, hydraulic motor, control valves and
connecting pipelines, etc.,
which constitute the hydrostatic transmission unit, have the problem of
efficiency in the entire
system unit; moreover, the volumetric efficiency and mechanical efficiency of
the pump and motor,
which affect the overall transmission efficiency of the unit, continuously
change with the speed,
consequently the transmission efficiency is instable. Therefore, on the
premise of maintaining the
stepless speed change capability of the hydraulic transmission unit, the
efficiency peak of the
hydraulic transmission unit shall be improved and the high efficiency area
under common operating
conditions shall be expanded, for the purpose of ensuring the transmission
efficiency and service
performance of the hydraulic-mechanical composite transmission system.
At present, in the design and development of hydraulic-mechanical CVTs, the
performance test is
usually carried out on a special test bench or device after the trial-
production of products. The
matching design scheme of the hydraulic transmission unit and mechanical
transmission unit of the
trial-products are often proved not the best through a series of tests, and
even the trial-production of
products has to be repeated, resulting in high cost and long cycle of product
design and
development and high consumption of manpower and material resources. Although
the product
design cycle and cost can be greatly reduced with the development of computer
simulation and
virtual prototyping technology, the inconsistency between the simulation
conditions and the actual
operating conditions also leads to uncertainties in product development.
III. Contents of the Invention
Technical Problem: the object of the present invention is to provide an
electric loading
multifunctional test bench for power dividing hydraulic-mechanical composite
transmission system
and application thereof, in order to overcome the drawbacks in the prior art.
Technical Solution: the present invention provides an electric loading
multifunctional test bench
for power dividing hydraulic-mechanical composite transmission system, which
comprises a
mechanical part and a control part, wherein
the mechanical part comprises:
a DC motor at the power input side of a hydraulic transmission unit, an
electromagnetic clutch at
the power input side of the hydraulic transmission unit, and a rotation speed
torque sensor at the
input side of the hydraulic transmission unit, which are connected
sequentially at an input side, a
tested hydraulic transmission unit, and a rotation speed torque sensor at the
output side of the
hydraulic transmission unit;
an AC variable frequency motor at the power input side of a mechanical
transmission unit, an
electromagnetic clutch at the power input side of the mechanical transmission
unit, and a rotation
speed torque sensor of the mechanical transmission unit, which are connected
sequentially at the
input side;
the rotation speed torque sensor at the output side of the hydraulic
transmission unit and the rotation
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speed torque sensor of the mechanical transmission unit are respectively in a
transmission
connection with an input shaft of a convergence mechanism; an output shaft of
the convergence
mechanism is in a transmission connection with a rotation speed torque sensor
at the output side and
a DC motor at the output side sequentially;
the control part comprises:
an industrial control computer, a signal acquisition unit and a programmable
logic controller (PLC),
which are respectively connected with the industrial control computer;
the signal acquisition unit is connected with the tested hydraulic
transmission unit via a pressure
sensor and a flow sensor; the signal acquisition unit is further connected
with the rotation speed
torque sensor at the input side of the hydraulic transmission unit, the
rotation speed torque sensor at
the output side of the hydraulic transmission unit, the rotation speed torque
sensor of the mechanical
transmission unit, and the rotation speed torque sensor at the output side
respectively;
the PLC is respectively connected with a D/A module at the input side of the
PLC, a D/A module at
the output side of the PLC, the electromagnetic clutch at the power input side
of the hydraulic
transmission unit, the electromagnetic clutch at the power input side of the
mechanical transmission
unit, and speed adjusting controller; wherein the D/A module at the input side
of the PLC is
respectively connected with the DC motor at the power input side of the
hydraulic transmission unit
and the AC variable frequency motor at the power input side of the mechanical
transmission unit via
a speed adjusting controller of the DC motor at the power input side of the
hydraulic transmission
unit and a frequency converter of the AC variable frequency motor at the power
input side of the
mechanical transmission unit; the D/A module at the output side of the PLC is
connected with the
DC motor at the output side via a speed adjusting controller of the DC motor
at the output side; the
speed adjusting controllers are respectively connected with the convergence
mechanism and the
tested hydraulic transmission unit.
Preferably, the DC motor at the power input side of the hydraulic transmission
unit, the AC variable
frequency motor at the power input side of the mechanical transmission unit,
and the DC motor at
the output side are all connected with a power supply source.
Preferably, the industrial control computer is further connected with an alarm
unit, a display, and
bench operating status indicator lights respectively.
Preferably, the DC motor at the power input side of the hydraulic transmission
unit is connected
with one end of the electromagnetic clutch at the power input side of the
hydraulic transmission unit
via a coupling, and the rotation speed torque sensor at the output side of the
hydraulic transmission
unit is in a transmission connection with a hydraulic transmission unit
coupling shaft of the
convergence mechanism.
Preferably, the AC variable frequency motor at the power input side of the
mechanical transmission
unit is connected with one end of the electromagnetic clutch at the power
input side of the
mechanical transmission unit via a coupling, and the other end of the
electromagnetic clutch at the
power input side of the mechanical transmission unit is in a transmission
connection with a
mechanical transmission unit coupling shaft of the convergence mechanism via a
coupling.
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Preferably, the convergence mechanism comprises: a planetary gear train that
is composed of a gear
ring of the planetary gear train, a planetary gear of the planetary gear train
and a planet carrier of the
planetary gear train; a fixed gear transmission unit that is composed of a
gear A and a gear B, a
clutch Li, a clutch L2, a clutch L3, a clutch L4, and actuator element of the
speed adjusting
controller; the hydraulic transmission unit coupling shaft, the mechanical
transmission unit coupling
shaft, and a convergence mechanism output shaft extend outwardly from the
convergence
mechanism. An advantage of the design lies in that different clutches in the
convergence mechanism
can be engaged to realize operating modes with different hydraulic power flow
and mechanical
power flow, and thereby performance test of the hydraulic transmission unit of
the
hydraulic-mechanical composite transmission system can be carried out under
all operating
conditions.
Preferably, the bench operating status indicator lights comprise a red light,
a green light, and a
yellow light. The function of the design is to enable the lights in different
colors to indicate different
operating statuses: the green light indicates a normal operating status; the
yellow light indicates a
normal shutdown status; the red light along with an audible alarm indicates an
abnormal stop status.
The present invention further provides an application of the electric loading
multifunctional test
bench for power dividing hydraulic-mechanical composite transmission system,
which comprises
the following steps:
operating modes for controlling engagement status of four clutches in the
convergence mechanism
by means of speed adjusting controller:
(1) forward power convergence transmission mode of hydraulic transmission
unit:
when the clutch L2 and the clutch L4 are engaged, the mechanical transmission
unit coupling shaft
is connected with the gear ring of the planetary gear train, the hydraulic
transmission unit coupling
shaft is always connected with a sun gear of the planetary gear train via the
fixed gear transmission
unit composed of the gear A and the gear B, and the convergence mechanism
output shaft is
connected with the planet carrier of the planetary gear train; at the moment,
the rotation speed of the
convergence mechanism output shaft increases as the rotation speed of the
hydraulic transmission
unit coupling shaft increases, forming forward convergence transmission in
which the outputted
rotation speed increases as the outputted rotation speed of the DC motor at
the power input side of
the hydraulic transmission unit increases;
(2) reversed power convergence transmission mode of hydraulic transmission
unit:
when the clutch Li and the clutch L3 are engaged, the mechanical transmission
unit coupling shaft
is connected with the planet carrier of the planetary gear train, the
hydraulic transmission unit
coupling shaft is always connected with the sun gear of the planetary gear
train via the fixed gear
transmission unit composed of the gear A and the gear B, and the convergence
mechanism output
shaft is connected with the gear ring of the planetary gear train; at the
moment, the rotation speed of
the convergence mechanism output shaft decreases as the rotation speed of the
hydraulic
transmission unit coupling shaft increases, forming reversed convergence
transmission in which the
outputted rotation speed decreases as the outputted rotation speed of the DC
motor at the power
input side of the hydraulic transmission unit increases;
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(3) mono-power transmission mode of hydraulic transmission unit:
when the clutch Li and the clutch L2 are engaged, the transmission ratio of
the planetary gear train
is 1, the mechanical transmission unit coupling shaft doesn't transfer power,
power is input from the
hydraulic transmission unit coupling shaft, and power is outputted from the
convergence
mechanism output shaft;
and, under the two-stage control of the industrial control computer and the
PLC, the DC motor and
the AC variable frequency motor implement different operating modes:
(1) constant torque mode: in that mode, under the regulation and control of
the control system and
control program, the motor is adjusted according to the comparison between the
feedback of
measured value of torque and a given value; by means of automatic regulation
through the
frequency converter and the controller in a given control mode, the output
torque of the motor
is changed and maintained at a set value;
(2) constant rotation speed mode: in that mode, under the regulation and
control of the control
system and control program, the motor is adjusted according to the comparison
between the
feedback of measured value of rotation speed and a given value; by means of
automatic
regulation through the frequency converter and the controller in a given
control mode, the
output rotation speed of the motor is changed and maintained at a set value;
(3) constant power mode: in that mode, the motor is under the regulation
and control of the control
system and control program, and the output power of the motor is maintained at
a given value;
thus, by means of two-stage control of the industrial control computer and
PLC, the dynamic
characteristics of the engine is simulated and a power source is provided for
the bench, so that the
test conditions for the tested hydraulic transmission unit are the closest to
the actual service
conditions, thereby the testing capability for the transmission system is
improved and the testing
range is extended.
Beneficial effects: compared with the prior art, the present invention has the
following advantages:
1) The electric loading multifunctional test bench for power dividing
hydraulic-mechanical
composite transmission system provided by the present invention can accomplish
performance
test of the hydraulic transmission unit of a hydraulic-mechanical composite
transmission
system. It can test the transmission performance of the hydraulic transmission
unit of the
hydraulic-mechanical composite transmission system by simulating and applying
the actual
travel conditions and operating conditions of a vehicle, test the performance
of the hydraulic
transmission unit in one-stage or multi-stage hydraulic-mechanical composite
transmission,
test the proportions of mechanical power flow and hydraulic power flow in the
composite
transmission system, automatically optimize the allocation ratio of mechanical
power flow to
hydraulic power flow, finally find out an optimal combination and allocation
scheme of
mechanical power flow and hydraulic power flow according to the universal
characteristic
curve of the matched engine, and provide power performance optimization for
the production
of vehicles in which the hydraulic-mechanical composite transmission system is
applied in the
future.
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2) The bench in the present invention can also provide a test platform for
testing the performance
of a hydrostatic transmission system and the performance of a complete
transmission system.
3) The bench in the present invention employs a rotation speed closed-loop
control system, which
has high stability in rotation speed test; in addition, the bench has a
reasonable structural
design, is simple and reliable, operates safely and reliably, is cost-saving,
and can realize a
function of reverse power generation if it is provided with a DC motor, so as
to achieve the
purpose of saving energy.
IV. Description of Drawings
FIG. 1 is a schematic structural diagram of the electric loading
multifunctional test bench for power
dividing hydraulic-mechanical composite transmission system in the present
invention;
FIG. 2 is a schematic diagram of the transmission structure of the convergence
mechanism in the
present invention;
FIG. 3 shows the control principle of the electric loading multifunctional
test bench for power
dividing hydraulic-mechanical composite transmission system in the present
invention.
In the figures: 1 - D/A module at input side of the PLC; 2 - programmable
logic controller (PLC); 3
- bench operating status indicator light; 4 - display; 5 - alarm unit; 6 -
industrial control computer; 7
- signal acquisition unit; 8 - flow sensor; 9 - pressure sensor; 10 - D/A
module at output side of the
PLC; 11 - speed adjusting controller; 12 - speed adjusting controller of the
DC motor at the output
side; 13 - DC motor at the output side; 14 - rotation speed torque sensor at
the output side; 15 -
convergence mechanism; 16 - rotation speed torque sensor at the output side of
the hydraulic
transmission unit; 17 - tested hydraulic transmission unit; 18 - rotation
speed torque sensor of the
mechanical transmission unit; 19 - rotation speed torque sensor at the input
side of the hydraulic
transmission unit; 20 - electromagnetic clutch at the power input side of the
mechanical
transmission unit; 21 - electromagnetic clutch at the power input side of the
hydraulic transmission
unit; 22 - AC variable frequency motor at the power input side of the
mechanical transmission unit;
23 - power supply source; 24 - DC motor at the power input side of the
hydraulic transmission unit;
25 - speed adjusting controller of the DC motor at the power input side of the
hydraulic
transmission unit; 26 - frequency converter of the AC variable frequency motor
at the power input
side of the mechanical transmission unit;
151 - hydraulic transmission unit coupling shaft; 152 - gear A; 153 - clutch
Li; 154 - clutch L2; 155
- gear ring of the planetary gear train; 156 - planetary gear of the
planetary gear train; 157 - clutch
L3; 158 - clutch L4; 159 - planet carrier of the planetary gear train; 160 -
convergence mechanism
output shaft; 161 - sun gear of the planetary gear train; 162 - gear B; 163 -
gear shaft of the sun gear;
164 - mechanical transmission unit coupling shaft.
V. Embodiments
Hereunder the present invention will be further detailed in examples with
reference to the
accompanying drawings, but the present invention is not limited to those
examples.
Example 1:
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As shown in Figs. 1-2, in this example, an electric loading multifunctional
test bench for power
dividing hydraulic-mechanical composite transmission system is provided, said
bench mainly
comprising two parts: a mechanical part and a control part:
the mechanical part comprises:
a DC motor 24 at the power input side of a hydraulic transmission unit, an
electromagnetic clutch
21 at the power input side of the hydraulic transmission unit, and a rotation
speed torque sensor 19
at the input side of the hydraulic transmission unit, which are connected
sequentially at an input
side, a tested hydraulic transmission unit 17, and a rotation speed torque
sensor 16 at the output side
of the hydraulic transmission unit;
an AC variable frequency motor 22 at the power input side of a mechanical
transmission unit, an
electromagnetic clutch 20 at the power input side of the mechanical
transmission unit, and a rotation
speed torque sensor 18 of the mechanical transmission unit, which are
connected sequentially at the
input side;
the rotation speed torque sensor 16 at the output side of the hydraulic
transmission unit and the
rotation speed torque sensor 18 of the mechanical transmission unit are
respectively in a
transmission connection with an input shaft of a convergence mechanism 15; an
output shaft of the
convergence mechanism 15 is in a transmission connection with a rotation speed
torque sensor 14 at
the output side and a DC motor 13 at the output side sequentially;
the control part comprises:
an industrial control computer 6, and a signal acquisition unit 7 and a
programmable logic controller
(PLC) 2, which are respectively connected with the industrial control computer
6;
the signal acquisition unit 7 is connected with the tested hydraulic
transmission unit 17 via a
pressure sensor 9 and a flow sensor 8; the signal acquisition unit 7 is
further connected with the
rotation speed torque sensor 19 at the input side of the hydraulic
transmission unit, the rotation
speed torque sensor 16 at the output side of the hydraulic transmission unit,
the rotation speed
torque sensor 18 of the mechanical transmission unit, and the rotation speed
torque sensor 14 at the
output side respectively;
the PLC 2 is respectively connected with a D/A module 1 at the input side of
the PLC, a D/A
module 10 at the output side of the PLC, the electromagnetic clutch 21 at the
power input side of
the hydraulic transmission unit, the electromagnetic clutch 20 at the power
input side of the
mechanical transmission unit, and speed adjusting controller 11; wherein the
D/A module 1 at the
input side of the PLC is respectively connected with the DC motor 24 at the
power input side of the
hydraulic transmission unit and the AC variable frequency motor 22 at the
power input side of the
mechanical transmission unit via a speed adjusting controller 25 of the DC
motor at the power input
side of the hydraulic transmission unit and a frequency converter 26 of the AC
variable frequency
motor at the power input side of the mechanical transmission unit; the D/A
module 10 at the output
side of the PLC is connected with the DC motor 13 at the output side via a
speed adjusting
controller 12 of the DC motor at the output side; the speed adjusting
controller 11 is respectively
connected with the convergence mechanism 15 and the tested hydraulic
transmission unit 17.
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The DC motor 24 at the power input side of the hydraulic transmission unit,
the AC variable
frequency motor 22 at the power input side of the mechanical transmission
unit, and the DC motor
13 at the output side are all connected with a power supply source 23.
The DC motor 24 at the power input side of the hydraulic transmission unit is
connected with one
end of the electromagnetic clutch 21 at the power input side of the hydraulic
transmission unit via a
coupling, one end of the rotation speed torque sensor 19 at the input side of
the hydraulic
transmission unit is connected with the electromagnetic clutch 21 at the power
input side of the
hydraulic transmission unit, the other end of the rotation speed torque sensor
19 at the input side of
the hydraulic transmission unit is connected with the input shaft of the
tested hydraulic transmission
unit 17, the output shaft of the tested hydraulic transmission unit 17 is
connected with one end of
the rotation speed torque sensor 16 at the output side of the hydraulic
transmission unit, the other
end of the rotation speed torque sensor 16 at the output side of the hydraulic
transmission unit is
connected with an hydraulic transmission unit coupling shaft of the
convergence mechanism 15,
and the pressure sensor 9 and the flow sensor 8 are connected with the tested
hydraulic transmission
unit 17; in the electrical control connection part, the output side of speed
adjusting controller 25 of
the DC motor at the power input side of the hydraulic transmission unit is in
an electric control
connection with the DC motor 24 at the power input side of the hydraulic
transmission unit, the
input side of the speed adjusting controller 25 of the DC motor at the power
input side of the
hydraulic transmission unit is in an electric control connection with the
output side of a D/A module
1 at the input side of the PLC, and the input side of the D/A module 1 at the
input side of the PLC is
in an electric control connection with the programmable logic controller (PLC)
2, the
electromagnetic clutch 21 at the power input side of the hydraulic
transmission unit is connected
with the programmable logic controller (PLC) 2, the rotation speed torque
sensor 19 at the input
side of the hydraulic transmission unit, the pressure sensor 9, the flow
sensor 8, and the rotation
speed torque sensor 16 at the output side of the hydraulic transmission unit
are connected with the
signal acquisition unit 7, and the speed adjusting controller 11 is connected
with the tested hydraulic
transmission unit 17.
The AC variable frequency motor 22 at the power input side of the mechanical
transmission unit is
connected with one end of the electromagnetic clutch 20 at the power input
side of the mechanical
transmission unit via a coupling, and the other end of the electromagnetic
clutch 20 at the power
input side of the mechanical transmission unit is connected with a mechanical
transmission unit
coupling shaft of the convergence mechanism 15 via a coupling; in the
electrical control connection
part, the frequency converter 26 of the AC variable frequency motor at the
power input side of the
mechanical transmission unit is in an electric control connection with the AC
variable frequency
motor 22 at the input side, the input side of the frequency converter 26 of
the AC variable frequency
motor and the electromagnetic clutch 20 at the power input side of the
mechanical transmission unit
are in an electric control connection with the output side of the D/A module 1
at the input side of the
PLC, and the rotation speed torque sensor 18 of the mechanical transmission
unit is connected with
the signal acquisition unit 7.
As shown in Fig. 2, a hydraulic transmission unit coupling shaft 151, a
mechanical transmission
unit coupling shaft 164, and a convergence mechanism output shaft 160 extend
outwardly from the
convergence mechanism 15; inside the convergence mechanism, a gear A 152 and a
gear B 162
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form a fixed gear transmission unit, a sun gear 161 of the planetary gear
train, a gear ring 155 of the
planetary gear train, a planetary gear 156 of the planetary gear train, and a
planet carrier 159 of
planetary gear train form a planetary gear train; the actuator elements of the
speed adjusting
controller include a clutch Li 153, a clutch L2 154, a clutch L3 157 and a
clutch L4 158. The
different clutches in the convergence mechanism can be engaged to realize
different convergence
modes of hydraulic power flow and mechanical power flow, and thereby
performance test of the
hydraulic transmission unit of the hydraulic-mechanical composite transmission
system can be
carried out under all operating conditions.
The industrial control computer 6 is further connected with an alarm unit 5, a
display 4, and bench
operating status indicator lights 3 respectively. The bench operating status
indicator lights 3
comprise a red light, a green light, and a yellow light. The lights in
different colors indicate different
operating statues: the green light indicates a normal operating status; the
yellow light indicates a
normal shutdown status; the red light along with an audible alarm indicates an
abnormal stop status.
Example 2:
As shown in Fig. 3, an operating method of an electric loading multifunctional
test bench for power
dividing hydraulic-mechanical composite transmission system that employs the
bench provided in
the technical solution of example 1, comprising the following operating steps:
operating modes for controlling engagement status of the four clutches in the
convergence
mechanism 15 by means of the speed adjusting controllers 11:
(1) forward power convergence transmission mode of hydraulic transmission
unit:
when the clutch L2 153 and the clutch L4 157 are engaged, the mechanical
transmission unit
coupling shaft 164 is connected with the gear ring 155 of the planetary gear
train, the hydraulic
transmission unit coupling shaft 151 is always connected with a sun gear 161
of the planetary gear
train via the fixed gear transmission unit composed of the gear A 152 and the
gear B 162, and the
convergence mechanism output shaft 160 is connected with the planet carrier
159 of the planetary
gear train; at the moment, the rotation speed of the convergence mechanism
output shaft 160
increases as the rotation speed of the hydraulic transmission unit coupling
shaft 151 increases,
forming forward convergence transmission in which the outputted rotation speed
increases as the
outputted rotation speed of the hydraulic motor of the hydraulic transmission
unit increases;
(2) reversed power convergence transmission mode of hydraulic transmission
unit:
when the clutch Li 154 and the clutch L3 158 are engaged, the mechanical
transmission unit
coupling shaft 164 is connected with the planet carrier 159 of the planetary
gear train, the hydraulic
transmission unit coupling shaft 151 is always connected with the sun gear 161
of the planetary gear
train via the fixed gear transmission unit composed of the gear A 152 and the
gear B 162, and the
convergence mechanism output shaft 160 is connected with the gear ring 155 of
the planetary gear
train; at the moment, the rotation speed of the convergence mechanism output
shaft 160 decreases
as the rotation speed of the hydraulic transmission unit coupling shaft 151
increases, forming
reversed convergence transmission in which the outputted rotation speed
decreases as the outputted
rotation speed of the hydraulic motor of the hydraulic transmission unit
increases;
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(3) mono-power transmission mode of hydraulic transmission unit:
when the clutch Li 154 and the clutch L2 153 are engaged, the transmission
ratio of the planetary
gear train is 1, the mechanical transmission unit coupling shaft 164 doesn't
transfer power, power is
input from the hydraulic transmission unit coupling shaft 151, and power is
outputted from the
convergence mechanism output shaft 160.
At the power input side, the hydraulic transmission part employs the DC motor
24 at the power
input side of the hydraulic transmission unit as a power source, the
mechanical transmission part
employs the AC variable frequency motor 22 at the power input side of the
mechanical transmission
unit as a power source, so that the speed ratio at the input side between the
hydraulic transmission
part and the mechanical transmission part can be adjusted freely, thereby the
speed ratio can be
automatically calibrated and compared, and an optimal proportion allocation
range for the
performance test of the hydraulic transmission unit in the entire composite
transmission system can
be determined; moreover, a control program can be worked out according to the
universal
characteristic curve of the selected matched engine, a power source can be
provided for the bench
by simulating the power characteristics of the engine under two-stage control
of the industrial
control computer 6 and the programmable logic controller (PLC) 2, so that the
operating conditions
of the tested hydraulic transmission unit in the test should be as close to
the actual operating
conditions as possible, thereby the testing capability for the transmission
system is improved and
the testing range is extended; according to the transmission characteristics
of the
hydraulic-mechanical composite transmission system, the hydraulic transmission
unit may have a
phenomenon of power backflow and circulation. In view of that phenomenon, the
hydraulic
transmission part employs a DC motor as the power source. Thus the DC motor
can realize a power
generation function in case of power backflow, and the generated electric
power can be fed back to
the power supply source, achieving an energy saving feature; engine exhaust
emission is avoided
under indoor test conditions of the bench, and thereby an environmental
protection feature is
achieved.
The device for simulating load at the power output side employs a DC motor 13
for loading at the
output side to simulate the load resistance under working conditions of the
vehicle. Under the
two-stage control of the industrial control computer 6 and the programmable
logic controller (PLC)
2, the resultant DC motor loading system has two operating states, i.e., a
power generation state and
an electric driving state. The generated electric energy is fed back to the
power supply source, so
that an energy saving feature is achieved. Moreover, the control system
employs a two-stage control
scheme with the industrial control computer and the programmable logic
controller (PLC) to
simulate the variations of power demand in the power transmission system of
the vehicle, thereby
the testing capability for the transmission system is improved and the
application range is extended.
Under the two-stage control of the industrial control computer 6 and the PLC
2, the DC motor and
the AC motor implement different operating modes:
(1)
constant torque mode: in that mode, under the regulation and control of the
control system and
control program, the motor is adjusted according to the comparison between the
feedback of
measured value of torque and a given value; by means of automatic regulation
through the
frequency converter and the controller in a given control mode, the output
torque of the motor
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is changed and maintained at a set value;
(2) constant rotation speed mode: in that mode, under the regulation and
control of the control
system and control program, the motor is adjusted according to the comparison
between the
feedback of measured value of rotation speed and a given value; by means of
automatic
regulation through the frequency converter and the controller in a given
control mode, the
output rotation speed of the motor is changed and maintained at a set value;
(3) constant power mode: in that mode, the motor is under the
regulation and control of the control
system and control program, and the output power of the motor is maintained at
a given value.
The motors of the hydraulic transmission unit and the mechanical transmission
unit at the input side
may be set in a constant rotation speed mode, and the loading motor at the
output side may be set in
a constant torque mode, a constant rotation speed mode, or a constant power
mode to simulate the
actual operating conditions; the convergence mechanism may be set in a forward
power
convergence transmission mode of the hydraulic transmission unit according to
the requirement of
the experiment for performance test of the hydraulic transmission unit during
forward power
convergence transmission; the convergence mechanism may be set in a reversed
power convergence
transmission mode of the hydraulic transmission unit for performance test of
the hydraulic
transmission unit during reversed power convergence transmission; when the
convergence
mechanism switches between the above two operating modes, the performance of
the hydraulic
transmission unit of a multi-stage hydraulic-mechanical composite transmission
system can be
tested. When the convergence mechanism is set in a mono-power transmission
mode of the
hydraulic transmission unit, the performance of a pure hydraulic transmission
system can be tested.
The bench operating status indicator lights comprise a red indicator light, a
green indicator light,
and a yellow indicator light. Their indications are as follows: the green
indicator light indicates a
normal operating status; the yellow indicator light indicates a normal
shutdown status; the red
indicator light along with an audible alarm indicates an abnormal stop status.
The computer displays
text and provides audible indications while the alarm unit provides the alarm
and the indicator lights
provide indications, until the all clear button is pressed.
Dynamic loading can be realized by means of a control program to simulate the
actual operating
conditions and specified cyclic operating conditions of the hydraulic-
mechanical composite
transmission system; according to different test schemes, the control system
and the control
program can set the rotation speeds and torques of the motors at the input
side and the output side to
different set values, and employ closed-loop control, which can fully meet the
requirements for
performance test of the hydraulic transmission unit of the hydraulic-
mechanical composite
transmission system and test of the ratio of mechanical transmission power
flow to hydraulic
transmission power flow in the entire transmission system; during the test,
the operator may debug
the control program according to the actual requirements and then simply press
a Start button, so as
to realize whole process control and performance test; the measured values and
result of analysis in
the test can be displayed, processed, stored, and printed in real time by
means of the industrial
control computer and the display. Compared with conventional benches, the
bench provided by the
present invention can perform performance test of the hydraulic transmission
unit of a
hydraulic-mechanical composite transmission system simply and reliably, and
can save test time
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and cost greatly.
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