Note: Descriptions are shown in the official language in which they were submitted.
8591
This invention relates to control valves and part-
icularly to control valves for use in an integral hydraulic
pump and valve assembly.
The use of integral hydraulic pump and valve
assemblies is not itself new. There are several forms of such
assemblies on the market. In one form the valve body circuitry
lS an integral part of the pump and cover. In another form the
valve body circuitry is a separate casting which is attached to
the end cover of a pump. Two of the important considerations
in such structures are compactness and simplicity. In all such
structures it is necessary to have a detent mechanism acting on
the valve spool and a stop mechanism for limiting the movement
in each direction. It has been conventional in these ~ ~-
mechanisms, as in ordinary control valves, to add a detent
mechanism on one end of the spool and a stop mechanism such as
snap rings and retainer rings on the two ends of the ~spool
,
outside the spool housing. These expedients necessarily add
length to the spool beyond that needed for the primary function
of directing the flow of oil. In addition the snap rings
and/or retainer rings are externally exposed which increases
the potential of a ring coming off which would permit the spooI
to over-travel.
The present invention~provides a structure in which
the problem of additional length and exposed stop members is
eliminated. In the structure of this invention r the detent
engages the spool in a reduced center area of the spool and a
cartridge carrying the detent acts as an internal stop in each
direction. ~n addition to eliminating the problems of excess
length and exposed stop means mentioned above, the structure of
this invention also makes it possible to use a symmetrical
1.
59
spool which can be inserted either way in the valve bore.
The valve structure of this invention comprises a
housing adapted to be attached to a pump housing and having a
low pressure port and a high pressure port adapted to connect
with the inlet and outlet ports of said pump, a low pressure
chamber, a high pressure chamber, and a cylinder chamber in
said housing spaced from one another and generally parallel
thereto, a transverse valve bore in said housing intersecting `
~; said chambers against one end, valve means movable axially in
said bore, said valve means having an annular groove inter-~`
mediate its ends capable of connecting said low pressure and
high pressure chambers in a first position, said low pressure,
high pressure and cylinder chambers in a second position and ~ -~
said low pressure chamber only in a third position, detent ~ -
means in said housing extending into said bore and annular
groove in the valve member, detent engaging means in said
groove intermediate its ends and stroke limiting means
surrounding said detent means and extending into said bore
within the annular groove in said valve member. Preferably the
detent means is a spring loaded poppet movable in the stroke
limiting means. The stroke limiting means is preferably a
hollow cylindrical barrel threaded into said housing and
extending into the bore. The valve means is preferably
symmetrical about the detent groove therein so that it may be
inserted either way in the bore. ;
In the foregoing general description we have set out
certain objects, purposes and advantages of our invention. -
Other objects, purposes and advantages of this invention will
be apparent from a consideration of the following description
and the accompanying drawings in which:
s~
Figure 1 is an end view of a valve structure
according to this invention;
Figure 2 is an end view from the opposite side of the
valve of Figure 1 showing the oil flow connection to a pump;
Figure 3 is a section on the line III-III of Figure
l;
Figure 4 is a section on the line IV-IV of Figure l;
and
Figure 5 is a section through the stroke limiting
means.
Referring to the drawings we have illustrated a
control valve for use in an integral hydraulic pump and valve
assembly. In the illustrated structure we provide a housing 10
adapted to be attached to one end oE a pump housing and having
a low pressure port 11 and a high pressure port lZ spaced apart `
on one end of the housing to match the low pressure and high
pressure ports of a pump. The housing has generally spaced
apart side-by-side low pressure chamber 13, high pressure
chamber 14 and cylinder chamber 15. A transverse bore 16
extends through the housing from side to side intersecting all
of chambers 13, 14 and 15. A valve member 17 having a central
groove 18 is slidable in said bore 16. Groove 18 is provided
with an annular detent engaging slot 19 midway between its
ends. The groove 18 is arranged so that in one position of
valve member 17 the low pressure chamber 13 and high pressure
chamber 14 are connected through bore 16; in a second position
all of chambers 13, 14 and 15 are connected; and in a third
position only low pressure chamber 13 is connected. A cylinder
port 20 is provided in the end of valve housing 10 opposite the
high pressure port 12 and the low pressure port 11. An inlet
35~`
port 21 is provided in the same end of housing 10 as the
cylinder port. A check valve 22 is provided between high
pressure chamber 14 and cylinder chamber 15 and a relief valve
23 is provided between cylinder chamber 15 and low pressure
chamber 13. A hollow cylindrical barrel stroke limiting means
24 is provided in housing 10 intersecting bore 16 and e~tending
into groove 18 to engage the ends of groove 18 when valve
member 17 is moved axially in bore 16 and thus limit the
movement of the valve member in said bore. A detent poppet 25
is movable in axial passage 26 in stroke limiting means 24 and
is urged to a position extending out of the end of bore 26 by
spring 27 acting on annular shoulder 28 on poppet 25, until
shoulder 28 bears on stops 29 in stroke limiting means 24.
Detent poppet 25 engages detent slot 19 in valve member 17 in
the neutral position of the valve member with groove 18
connecting the low pressure chamber 13 and high pressure
chamber 14. Thus, the operator has an indicator of neutral
position and the valve is held there by the detent poppet 25
resting in the detent slot 19. Movement of the valve member to
the second position to the right view of Figure 3 wlth groove
18 abutting the stroke limiting means 24 connects all chambers
and permits fluid to return from cylinder port 20 back to the
low pressure chamber. Movement of the valve member to the
third position (to the left viewing Figure 3) with the opposite
end of groove 18 abutting the stroke limiting means 24, closes
the bore to all chambers except chamber 13. This causes the
high pressure fluid coming from the pump through high pressure
port 12 and into high pressure chamber 14 to open check valve
22 and pass into cylinder chamber 15 and out cylinder port 20
to a h~draulic cylinder or other working device.
~;Z8S9
In the foregoing specification we have set out
certain preferred practices and embodiments of our invention,
however, it will be understood that this invention may be
otherwise practiced within the scope of the following claims.
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