Hydraulic pump apparatus

A hydraulic apparatus as used for providing fluid to a steering gear of an automotive vehicle includes a housing (10) having a valve bore (14) housing a relief valve spool (94) disposed therein and slidable between a first and second position. A discharge connector (88) is disposed on a first end of the valve bore (14) and forms a fluid passage for communicating fluid through the first end of the valve bore to a power steering actuator. An annular retainer (90) is disposed in the valve bore between the first position of the spool valve (94) and the discharge connector (88). The annular retainer includes an outer periphery (130) sized for interference fit engagement with said valve bore (14) for retaining the spool valve (94) within the valve bore (14) when the discharge connector (88) is removed from the first end of the valve bore.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to hydraulic pumps as used in automotive 
vehicles. More particularly, the present invention relates to hydraulic 
devices, such as pumps, having a slidable valve within a bore, and 
specifically to an apparatus for retaining the valve within the bore while 
the device is being serviced. 
2. Disclosure Information 
Hydraulic pumps are well known to those skilled in the hydraulics art, as 
are many forms of actuators having sliding valves therein. Commonly these 
valves are used to control fluid flow within the pump, actuator etc. The 
valves are commonly located within a valve bore and are free to slide 
between at least two predetermined positions. Additionally, the bore is 
generally manufactured to allow the valve to slide completely out at least 
one end of the bore. This accommodates assembly, and where necessary, 
service of the valve assembly. 
It was recently observed that in certain circumstances, it is desirable to 
orient power steering pumps such that a longitudinal axis the bore is 
generally aligned parallel to the vertical axis as installed in the 
vehicle. It was further observed that during service of hydraulic lines 
and connectors attaching to the pump, the valve could be displaced from 
the bore inadvertently. Thus necessitating service of the valve assembly 
where not necessarily required. 
It would therefore be advantageous to provide a hydraulic apparatus that 
could be oriented having a vertical valve bore that would not require 
inadvertent service of the valve assembly during service of hydraulic 
lines and their associated connectors. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention provides a hydraulic apparatus providing 
positive retention of a valve within a bore, such that the hydraulic 
apparatus may be serviced without inadvertently requiring valve service. 
An example of the hydraulic apparatus, such as the type used for providing 
fluid to a steering gear of an automotive vehicle has been described 
herein. 
The hydraulic apparatus includes a housing having a valve bore and first 
and second ends therein. The hydraulic apparatus further includes a spool 
valve disposed in the valve bore and slidable between a first and second 
position and a discharge connector having threads on an outer 
circumference thereof for engaging internal threads disposed on the first 
end of the valve bore. The discharge connector forms a fluid passage for 
communicating fluid through the first end of the valve bore. 
The hydraulic apparatus also includes an annular retainer disposed in the 
valve bore between the first position of the spool valve and the discharge 
connector, the annular retainer having an outer periphery sized for 
interference fit engagement with the valve bore for retaining the spool 
valve within the valve bore when the discharge connector is removed from 
the first end of the valve bore. 
Advantageously, the annular retainer positively retains the spool valve 
within the valve bore in the absence of the discharge connector, allowing 
service of the discharge connector and any associated components, such as 
fluid line and couplings, without requiring inadvertent service of the 
spool valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIGS. 1 and 2, the present invention will now be described 
as applied to a power steering pump as used in a automotive vehicle. It 
should be recognized, however, that the present invention may be employed 
with similar advantage in many hydraulic devices having internal valve 
mechanisms and external hydraulic lines, such as suspension actuators, 
hydraulic brake devices, etc. 
A rotary vane hydraulic power steering pump constructed in accordance with 
the present invention supplies pressurized fluid to an automotive vehicle 
steering gear. The pump includes a housing 10 defining a cylindrical space 
12 containing the pumping elements, a bore 14 having first and second ends 
15, 17 containing a flow control valve and related components and a 
diffuser passage 18. The housing includes at least three bosses 20-22, 
each having a cylindrical hole adapted to receive a mechanical attachment 
such as a bolt, which can be threaded directly to the engine block of the 
vehicle. In this way, the conventional bracket usually used to support a 
power steering pump located in position to be driven by a belt from the 
engine crankshaft can be eliminated. 
The components that pump hydraulic fluid from a reservoir to the steering 
gear are rotatably supported on a shaft 24, driven by an endless drive 
belt from an engine and rotatably connected by a splined connection to a 
rotor 26 fixed in position on the shaft by a snap ring 28. The rotor has 
ten radially sliding vanes 30, held in contact with the inner surface of a 
cam ring 32 having two arcuate zones extending angularly in rise or inlet 
quadrants and two zones of lesser radial size extending angularly in fall 
or outlet quadrants mutually separated by the inlet quadrants. A lower 
pressure plate 34 and an upper pressure plate 36 are fixed in position 
radially with respect to the cam 32 by alignment pins 38. Formed through 
the thickness of the upper pressure plate are arcuate outlet ports 40, 42 
communicating with an outlet port opening to the flow control valve bore 
14, inlet ports 44, 46 and arcuate passages 48, 50 for use in cold 
starting priming. The lower pressure plate has inlet ports 56, 54 formed 
through its thickness, outlet ports 58, 60 and arcuate flow passages 62, 
64 hydraulically connected to passages 48, 50. 
A wire retaining ring 66 seats within a recess at the end of the pump 
housing to hold in position a pump cover 68. Bushing 70 supports shaft 24 
on a recess in the inner surface of the cover. Seal 72 prevents the 
passage of hydraulic fluid. 
The opposite end of the rotor shaft is supported rotatably in a bushing 74, 
which is supported on the housing; a shaft seal 76 prevents flow of 
hydraulic fluid from the pumping chambers. Located adjacent the lower 
pressure plate on the opposite side from the cam are an inner seal 78, an 
outer seal 80, and a Belleville spring 82, which develops an axial force 
tending to force mutually adjacent surfaces of the various components into 
abutting contact. 
Located within bore 14 are a discharge port orifice 84, integrally formed 
with a discharge connector 88, a seal 86, and an annular retainer ring 90. 
The discharge connector 88 has a threaded portion 89 for engagement with a 
threaded portion 92 of the valve bore 14. Also located within bore 14 is a 
relief valve spool 94, a coiled compression spring, ball, and ball seat 96 
and a larger compression spring 98 urging spool 94 toward a first position 
where the flow control valve is closed corresponding to low pump speed 
operation. A seal 100 and plug 102 close the adjacent end of the bore 
mechanically and hydraulically. 
A tube assembly 104 connects a tube carrying fluid from the steering gear 
to the pump housing, through which it passes in suitable ports to the 
pumping chamber. 
Referring now to FIGS. 2 through 6, the annular retainer ring 90 is 
disposed within the bore 14 between a first position of the valve spool 94 
and the inner end of the discharge connector 88. The annular retainer 90 
includes an outer periphery 130 sized for interference fit engagement with 
the bore 14. In the preferred embodiment, the outer periphery of the 
annular retainer includes a plurality of protuberances 132 projecting 
radially outward for engagement with the bore 14. The protuberances may be 
tapered, having a low end 134 of the taper adjacent to the valve spool 94 
and the high end 136 adjacent to the discharge connector 88. 
The annular retainer 90 also includes an inner periphery 140 sized for 
interference fit engagement with the discharge port orifice 84. The inner 
periphery 140 may include flats 142 protruding inwardly from the otherwise 
circular periphery of the annular retainer. Depending on the amount of 
interference desired, small flats may be formed just adjacent to the spool 
valve 94, or if greater interference is desired, larger flats may extend 
further into the inner periphery 140 of the annular retainer 90. 
Advantageously, the amount of taper on the protuberances 132 and the size 
of the flats 142 can be varied so as to create a relationship permitting 
the removal of the discharge port orifice without causing the annular 
retainer to be removed from the bore 14. This is accomplished by the 
combination of greater surface area contacted by the outer diameter than 
the inner diameter together with a sufficient taper on the protuberances 
132 to create a higher retaining force than that created by the 
interference between the flats and the discharge port orifice. This is 
particularly advantageous where automated assembly equipment is used and 
the retainer 90 must stay on the discharge port orifice until it is 
assembled into the valve bore. 
Operation of the relief valve spool 94 will now be described with reference 
to FIGS. 2 and 7. Pressurized fluid flows from the outlet ports in the 
pressure plates through port 112 to bore 14 in which relief valve spool 94 
is located. Orifice 84 has an axially directed passage 114, which 
continually connects port 112 to the pressure tube 116, which carries high 
pressure hydraulic fluid to the steering gear from the pump. 
The flow rate through port 112 is proportional to the speed of the pump 
shaft 24 and to the speed of the engine to which that shaft is connected. 
Directing fluid flow into passage 114 produces a pressure drop relative to 
pressure at port 112. Pressure downstream of aperture 114, the steering 
system pressure, is fed back in passage 115 to the end of the relief valve 
spool 94 contacted by spring 98. A force resulting from the feedback 
pressure adds to the spring force on the spool. When pump speed increases, 
hydraulic system pressure in port 112 increases, thereby forcing relief 
valve spool 94, against the effect of compression spring 98 and the 
feedback pressure, away from the first position toward a second position 
(as shown in FIG. 7) where additional fluid flow is bled back to a fluid 
reservoir through the diffuser passage 18. This operating condition may 
also be referred to as the high speed operating mode, as it occurs when 
the pump operates at high speeds. 
In the event the discharge connector 88 must be removed, such as to service 
pressure tube 116, the spring 98 urges the relief valve spool 94 against 
the annular retainer 90. The annular retainer 90 positively resists 
sliding of the relief valve spool 94, so as to prevent inadvertent 
disassembly of the relief valve spool 94. A hooked object may be inserted 
in bore 14 to forcibly remove the retainer 90 if servicing the relief 
valve spool 94 is specifically desired. 
The foregoing description presents a preferred embodiment of the present 
invention. Details of construction have been shown and described for 
purposes of illustration rather than limitation. Modifications and 
alterations of the invention such as this will no doubt occur to those 
skilled in the art that will come within the scope and spirit of the 
following claims.