Note: Descriptions are shown in the official language in which they were submitted.
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LUBRICANT PUMP AND LUBRICATING SYSTEM WITH PUMP HEATER
The present invention pertains to a lubricant pump for delivering lubricant to
at least one
lubricating point, as well as to a lubricating system with such a lubricant
pump. The lubricant
pump features, e.g., a lubricant container, a pump unit, a drive assigned to
the pump unit, at least
one lubricant outlet and a control unit assigned to the drive.
Some known lubricant pumps are provided with a functional monitoring system
that
delivers a corresponding malfunction signal to a monitoring device, e.g., if
an impermissibly
high pressure at the lubricant outlet indicates that the lines leading to the
lubricating points are
blocked. It is also known that the drive of the pump unit or the drive of an
agitator blade that
may be provided in the lubricant container automatically switches off at an
excessively high load
and, if applicable, also delivers a malfunction signal. When such a
malfunction signal is
registered in the monitoring device, the pump usually is completely stopped
and needs to be
reactivated by an operator after the cause of the malfunction is eliminated.
This is a time-
consuming and labor-intensive procedure.
Such an intervention by the operator in order to activate the pump is also
required if no
malfunction of the pump has occurred, but the viscosity of the lubricant
merely has increased at
low temperatures to such a degree that the function of the lubricant pump is
impaired.
Consequently, it has already been proposed to provide a heater that heats
parts of the lubricant
pump. Such heaters are usually switched on individually without realizing a
demand-actuated
operation of the heater.
The present invention, in contrast, is based on the objective of making
available a
lubricant pump and a lubricating system of the aforementioned type that are
particularly suitable
for use in extremely cold areas such as, e.g., in arctic environments.
According to the invention, this objective is essentially attained with the
characteristics of
Claim 1. According to the basic concept of the invention, the lubricant pump
additionally
features at least one heating element that can be actuated in a demand-based
fashion by the
control unit assigned to the drive and/or a separate control unit. In other
words, the heater
according to the present invention can always be purposefully utilized when a
malfunction of the
lubricant pump can be attributed to increased lubricant viscosities at low
temperatures. In such
instances, the pump therefore no longer needs to be completely stopped and the
cause of the
malfunction no longer needs to be eliminated by an operator, but the lubricant
pump rather can
be automatically restarted by actuating the heating element.
An increased viscosity of the lubricant at low temperatures, as can occur,
e.g., in arctic
environments or under harsh winter conditions, can cause different
malfunctions within a
lubricant pump. For example, blocking of the driving motor may occur if the
resistance becomes
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excessively high for movement of the agitator blade in the lubricant
container. It would also be
possible that the flow resistance in one of the lubricant lines exceeds the
permissible system
pressure such that a conventionally provided pressure control valve opens.
This causes the
lubricant to be delivered into the open rather than to the lubricating points.
Another malfunction
may consist of the pump element being unable to take in lubricant of increased
viscosity from the
lubricant container. The utilization of a heater in the lubricant pump only
makes it possible to
eliminate the malfunctions in the first and the last above-cited instance.
However, an excessively
high flow resistance in one of the lubricant lines cannot be eliminated by
using a heater within
the lubricant pump. According to the invention, it is therefore proposed that
the control unit
activates the heating element individually and in dependence on the respective
malfunction.
Independently of the above-described characteristics, the control device of a
lubricant
pump of the initially cited type is, according to a basic principle of the
present invention, realized
and designed in such a way that the above-described malfunctions caused by an
increased
viscosity of the lubricant at excessively low temperatures are detected by the
control device and
corresponding countermeasures are initiated.
According to an additional development of this inventive principle, it is
proposed that the
lubricant pump additionally features at least one temperature sensor that is
connected to the
control unit and/or another control unit in order to actuate the at least one
heating element in
dependence on the temperature determined by the temperature sensor. Due to
this temperature
sensor, the control unit is able to detect whether a malfunction can be
attributed to an increased
viscosity of the lubricant due to an excessively low temperature and to then
individually
eliminate this malfunction by switching on the heating element.
According to another embodiment of the invention, at least one pressure sensor
is
provided in the lubricant pump and preferably assigned to the lubricant
outlet. The pressure
sensor is preferably connected to the control unit or another control unit in
order to actuate the at
least one heating element in dependence on the lubricant pressure determined
by the pressure
sensor. If the flow resistance in one of the lubricant lines exceeds the
permissible system
pressure due to excessively low temperatures, however, the use of a heating
element in the
lubricant pump does not eliminate the cause of the malfunction. In this
respect, an unnecessary
operation of the heating element can be prevented in dependence on the
lubricant pressure
determined by the pressure sensor.
An agitating device such as, e.g., an agitator blade may be provided in the
lubricant
container. This agitating device can be actuated by the drive of the pump unit
and/or by another
drive. A measuring device is preferably assigned to the drive of the agitating
device in order to
determine the current consumption thereof and connected to the control unit
and/or another
control unit in order to actuate the at least one heating element in
dependence on the current
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consumption. Consequently, the measuring device enables the control unit to
determine whether
the driving motor is blocked due to an excessively high resistance of the
agitator blade in the
lubricant container that is caused by an increased viscosity of the lubricant
at low temperatures.
Instead of measuring the current consumption of the drive, the measuring
device may also
measure another variable that is suitable for determining the state of the
lubricant in the lubricant
container and then evaluated by the control unit. Such a variable may consist,
e.g., of the torque
required for driving the agitator blade and/or the speed of the agitator
blade.
It is preferred to design the control unit in such a way that it detects a
state in which the
drive for the agitating device is blocked due to excessively low temperatures,
based on an
evaluation of the data of the temperature sensor, the measuring device and/or
the pressure sensor.
In this respect, it is preferred that the control unit switches on the at
least one heating element in
this state in order to increase the temperature of the lubricant in the
lubricant pump and the
lubricant container, respectively. The quantity of heat can be controlled with
the heating time, if
applicable, in dependence on the ambient temperature. It is preferred that the
heating process
begins prior to a lubrication cycle, wherein the ambient temperature is
initially measured and a
quantity of heat that prevents the agitator blade from being blocked is
subsequently supplied.
According to another embodiment of the invention, the control unit is designed
in such a
way that it detects a state in which the pump unit is unable to take in
lubricant from the lubricant
container due to excessively low temperatures, based on an evaluation of the
data of the
temperature sensor, the measuring device and/or the pressure sensor. In this
state, the control unit
preferably also switches on the heating element provided in the lubricant pump
in order to supply
heat to the pump system. According to another embodiment of the invention, it
is proposed to
design the control unit such that it detects a state in which an excessively
high flow resistance
exists in a line connected to the lubricant outlet due to excessively low
temperatures, based on an
evaluation of the data of the temperature sensor, the measuring device and/or
the pressure sensor.
It is preferred that the control unit switches off the drive of the pump unit
and/or the drive of the
agitating unit in this state because an actuation of the lubricant pump would
cause the lubricant
to be delivered into the open via the pressure control valve rather than to
the lubricating point.
This malfunction cannot be eliminated by heating the pump system because the
viscosity of the
lubricant increases in the lubricant lines outside the pump. Consequently, it
is also unnecessary
to output a malfunction signal, but rather preferred to wait until the ambient
temperature
increases and the resistances in the lines drop.
A particularly compact and protected construction of the inventive lubricant
pump can be
achieved in that the control unit, the temperature sensor, the measuring
device, the pressure
sensor, the at least one drive and the pump unit are accommodated in a common
housing and/or
arranged on a common carrier. The housing may also fulfill a certain
insulating function in order
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to retain the heat generated by the heating element within the region of the
pump through which
the lubricant flows.
The invention also pertains to a lubricating system with a lubricant pump of
the above-
described type and a line that is connected to the lubricant outlet of the
lubricant pump and to a
distributor. In this case, the distributor preferably features a functional
sensor that is connected to
the control unit of the lubricant pump and/or another control unit in order to
actuate the at least
one heating element of the lubricant pump in dependence on the operability of
the distributor. In
other words, it is possible to refrain from the energy-intensive utilization
of the heater if a
malfunction of the distributor occurs, namely even if the viscosity of the
lubricant increases
within the lubricant pump due to excessively low temperatures.
In addition, at least one other heating element that can be actuated by the
control unit
and/or another control unit may also be assigned to the distributor and/or the
line. This actuation
preferably takes place in dependence on the data of the functional sensor, the
temperature sensor,
the measuring device and/or the pressure sensor. In this way, not only can
temperature-related
malfunctions within the lubricant pump be eliminated, but also malfunctions
that are caused by
the viscosity of the lubricant increasing within the distributor or in a line
leading to or away from
the distributor at low temperatures.
An embodiment example of the invention is described in greater detail below
with
reference to the figures. In this respect, all described and/or graphically
illustrated characteristics
form the object of the invention individually regardless of the composition
thereof in the claims
or the references thereof to other claims. The only figure schematically shows
a perspective
representation of an inventive lubricant pump. In order to provide a better
overview, certain
components of the lubricant pump, such as the cover of the housing, are not
illustrated such that
the individual components are visible in the figure.
The inventive lubricant pump 1 features a lubricant container 2, in which a
supply of
lubricant is stored. An agitator blade or similar agitating device may be
provided in the lubricant
container 2 in order to thoroughly mix and maintain the free-flowing
consistency of the lubricant
that may consist, e.g., of lubricating grease. In the figure, a carrier 3 is
provided on the lower side
of the lubricant container 2, wherein the carrier can be closed with a housing
cover and the
components of the lubricant pump I are arranged on this carrier.
In order to deliver lubricant from the lubricant container 1 to a lubricant
outlet, the
lubricant pump features a pump unit that can be actuated by a driving motor 4.
The driving motor
4 may also drive the agitating device in the lubricant container 2.
In addition, a control 5 that can individually actuate the driving motor 4 and
the pump
unit and/or the agitating unit is also provided on the carrier 3. In the
embodiment shown, a
cartridge heater 6 is also arranged on the underside of the lubricant
container 2 on the carrier 3
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and can be actuated by the control 5. In this case, the cartridge heater 6 is
arranged in the vicinity
of the pump unit such that the cartridge heater can heat the lubricant
situated in the lubricant
container 2, as well as the pump unit.
The inventive lubricant pump I is furthermore equipped with a pressure sensor
7 and a
temperature sensor 8 that are also arranged on the carrier 3. The pressure
sensor 7 and the
temperature sensor 8 are connected to the control 5 that evaluates the data
acquired by the
pressure sensor 7 and the temperature sensor 8 and activates the driving motor
4 and/or the
cartridge heater 6 in dependence on the data of the sensors. The temperature
sensor 8 measures
the ambient temperature. The pressure sensor 7 measures the lubricant pressure
at the lubricant
outlet or in the line connected thereto. In addition, the control 5 may also
determine, e.g., the
current consumption of the driving motor 4 or the torque required for driving
the pump unit
and/or the agitator blade with the aid of a corresponding measuring device.
In this way, the control 5 is able to detect different malfunctions of the
lubricant pump 1
that are caused by an increased viscosity of the lubricant due to excessively
low temperatures.
An evaluation of the ambient temperature and/or the current consumption of the
driving motor 4
makes it possible to determine whether the driving motor is blocked due to an
excessively high
resistance of the agitator blade in the lubricant container 2. In motors that
are protected against
blocking, the power supply is usually interrupted. The current consumption can
be evaluated on
motors that do not feature this protection. An evaluation of the ambient
temperature and the data
of the pressure sensor 7 makes it possible to determine whether the flow
resistance in the lines
connected to the lubricant outlet is so high that a pressure control valve is
actuated and lubricant
is delivered into the open. An evaluation of the ambient temperature, the
current consumption of
the driving motor 4 and the data of the pressure sensor 7 makes it possible to
determine whether
the pump unit is able to take in grease from the lubricant container 2. If
applicable, the data of a
functional sensor of a distributor, not shown, may also be evaluated for this
purpose, wherein
said distributor forms part of the lubricating system and is connected to the
lubricant outlet of the
lubricant pump 1.
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List of reference symbols
1 Lubricant pump
2 Lubricant container
3 Carrier
4 Driving motor
Control
6 Cartridge heater
7 Pressure sensor
8 Temperature sensor
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