Valve body assembly with detent and locking mechanism

A valve assembly including a valve housing with a spool valve mounted for reciprocation within the valve housing, with a detent mechanism disposed on the spool valve and the valve housing for selectively locking the spool valve against reciprocal movement, and for providing an externally observable indicator of valve position. In an illustrative embodiment, the detent assembly of the present invention includes at least one detent pin disposed on the spool valve, with at least one guide flange disposed on the valve housing. The guide flange is adapted to at least partially surround the detent pin. At least one retaining clip is provided which is adapted for insertion through the guide flange to engage the detent pin. When the retaining clip is inserted through the guide flange and in engagement with the detent pin, the spool valve is locked into a predetermined stationary position, and cannot reciprocate. The detent assembly can also include at least one detent pad disposed in the valve housing which is capable of operative engagement with the detent pin in order to provide a physical indication of the position of the spool valve. The detent pad can be provided in the form of an elastomeric washer disposed at one end of the valve housing. The elastomeric washer is provided with a central aperture having a diameter that is substantially less than the outer diameter of the detent pin of the spool valve. The detent pin can be provided with a recessed groove which interacts with the detent pad to provide a tactile indication that the spool valve has reached a predetermined position.

TECHNICAL FIELD 
The present invention relates to reciprocating control valve assemblies, 
and specifically to spool valve assemblies used as reversing valves for 
reciprocating pumps, such as diaphragm pumps. 
BACKGROUND OF THE INVENTION 
It is known to use reciprocating valves, specifically spool valves, as 
reversing valves for controlling the operating of reciprocating pumps. 
Such valves are disclosed in conjunction with diaphragm pumps in, for 
example, U.S. Pat. No. 3, 304,126 and U.S. Pat. No. 4,472,115. In 
apparatus such as those disclosed in these patents, a spool valve, often 
under the influence of a pilot valve, is shifted back and forth to reverse 
the flow of motive fluid from one side of a diaphragm to the other, thus 
causing the diagram to reciprocate. Such valves are generally provided in 
enclosed chambers, thus making it impossible to determine the position of 
the spool valve by observation of the outside of the spool valve housing. 
Furthermore, conventional spool valves provide no means by which the spool 
valve can be secured in one position during servicing or maintenance of 
the pump or pump control system. 
It can thus be seen that the need exists for a valve assembly wherein the 
position of the valve can be easily detected, and wherein the valve can be 
secured in a stationary position during maintenance or servicing of the 
pump. 
SUMMARY OF THE INVENTION 
The present invention provides a valve assembly that overcomes the 
abovenoted shortcomings of the prior art by providing a valve assembly 
including a valve housing with a spool valve mounted for reciprocation 
within the valve housing, with a detent and locking mechanism disposed on 
the spool valve and the valve housing for selectively locking the spool 
valve against reciprocal movement, and for providing an externally 
observable indicator of valve position and for providing a detent 
arrangement to prevent inadvertent valve reciprocation during pump 
operation. In an illustrative embodiment, the detent assembly of the 
present invention includes at least one detent pin disposed on the spool 
valve, with at least one guide flange disposed on the valve housing. The 
guide flange is adapted to at least partially surround the detent pin. At 
least one retaining clip is provided which is adapted for insertion 
through the guide flange to engage the detent pin. When the retaining clip 
is inserted through the guide flange and in engagement with the detent 
pin, the spool valve is locked into a predetermined stationary position, 
and cannot reciprocate. The detent assembly can include at least one 
detent pad disposed in the valve housing which is capable of operative 
engagement with the detent pin in order to provide a physical indication 
of the position of the spool valve and to prevent unwanted spool movement 
during pump operation. The detent pad can be provided in the form of an 
elastomeric washer disposed at one end of the valve housing. The 
elastomeric washer is provided with a central aperture having a diameter 
that is substantially less than the outer diameter of the detent pin of 
the spool valve. The detent pin can be provided with a recessed groove 
which engages the detent pad. 
In an illustrative embodiment, the valve assembly can include an internal 
bore adapted to receive the valve spool, with a pair of end caps secured 
at opposite ends of the valve body. The end caps are provided with 
apertures that are adapted to surround the detent pins of the spool valve. 
The guide flanges can be mounted on the respective end caps. The valve 
assembly can also include end cap bushings mounted within the end caps to 
provide a seal between the valve housing and the detent pins. The guide 
flanges can be provided as substantially U-shaped flanges extending 
longitudinally from the end caps, with a transverse bore in the U-shaped 
flange that is adapted to receive the retaining clip. The spool valve may 
include a valve sleeve in which a valve spool is mounted for 
reciprocation. A pair of spool bumpers can be mounted at opposite ends of 
the valve sleeve to cushion the valve spool during reciprocation. 
Other objects and advantages of the present invention will be apparent upon 
reference to the accompanying description when taken in conjunction with 
the following drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A valve assembly 10 embodying the principles of the present invention is 
illustrated in FIG. 1. The valve assembly 10 includes a valve housing 12 
in which a spool valve 14 is mounted for reciprocation. The valve assembly 
10 may be used as part of a pneumatic or hydraulic control system for a 
diaphragm pump, as described in the Background of the Invention. The spool 
valve 14, as illustrated, includes a valve sleeve 16 mounted within the 
valve housing 12. A pair of O-rings 18 provide a fluid seal between the 
valve sleeve 16 and an internal bore 20 of the valve housing 12. A valve 
spool 22 is mounted for reciprocation within the valve sleeve 16. A pair 
of spool bumpers 24 are provided at opposite ends of the valve housing 12, 
and act to cushion the valve spool 22 at the limits of its reciprocation. 
The valve housing 12 is closed at each end by a respective end cap 26. The 
end caps 26 are secured to the valve housing 12 by an appropriate 
fastening mechanism 28 such as hex-head capscrews. 
The valve spool 22 is provided with a pair of detent pins 30. The detent 
pins 30 extend from opposite ends of the valve spool 22 along a 
longitudinal axis thereof. Each of the detent pins 30 is provided with a 
recessed groove 32 that extends circumferentially around the detent pin, 
and is also provided with a transverse bore 34 extending diametrically 
through the detent pins 30. The functions of the recessed grooves 32 and 
transverse bores 34 will be described in detail hereinbelow. The detent 
pins 30 are of sufficient length to extend through the respective end caps 
26. A pair of end cap bushings 36 are provided within the end caps 26 to 
provide a fluid tight seal between the detent pins 30 and the end caps 26. 
As can be seen in FIG. 1, the present invention may include a pair of 
detent pads 40 located at opposite ends of the valve housing 12. The 
detent pads 40 may be provided by elastomeric washers having central 
apertures 42. The central apertures 42 have a diameter substantially less 
than the diameter of the detent pins 30, and are positioned such that the 
detent pad 40 is capable of operative engagement with the recessed groove 
32 of the detent pin 30, as shown in the right-hand side of FIG. 1. 
Engagement of the detent pad 40 with the recessed groove 32 of the detent 
pin 30 provides a resistance to unwanted or inadvertent movement of the 
valve spool 22, while also providing tactile indication of spool valve 
position when the valve spool 22 is manually moved to effect such 
engagement. The degree of resistance can be modified as desired by 
modifying the size of the aperture 42 or by changing the holding strength 
of the pads 40. 
The valve assembly 10 is also provided with a pair of guide flanges 44. 
Each of the guide flanges 44 extends generally longitudinally from the 
respective end caps 26. The guide flanges 44 may be provided as a pair of 
U-shaped flanges extending longitudinally from the end caps such that the 
guide flanges 44 at least partially surround the detent pins 30 when they 
are in a position extending out of the end caps 26. As shown in FIG. 2, 
the guide flanges 44 are provided with transverse bores 46 that are 
capable of alignment with the transverse bores 34 of the detent pins 30. 
The transverse bore 34 of the detent pin 30 and the transverse bores 46 of 
the guide flanges 44 are adapted to receive a retaining clip 48. When the 
retaining clip 48 is inserted through the transverse bores 46 of the guide 
flanges 44 and the transverse bore 34 of the detent pin 30, the spool 
valve is locked against reciprocation. With the spool valve locked against 
reciprocation, service, maintenance, or other procedures may be performed 
on the diaphragm pump associated with the valve assembly 10 with the 
knowledge that the reversing valve will remain stationary, thus preventing 
accidental displacement of the pump. 
It is, of course, to be understood that the foregoing description is for 
illustrative purposes only, and that the principles of applicants 
inventions are amendable to other specific embodiments. For example, it is 
contemplated that the valve assembly could be provided with only one 
detent pin rather than the pair of detent pins as shown in the illustrated 
embodiment. 
Although the present invention has been described with reference to a 
specific embodiment, those of skill in the art will recognize that changes 
may be made thereto without departing from the scope and spirit of the 
invention as set forth in the appended claims.