Modulator valve

A modulator valve has a modulator member which is slidably mounted in a cylinder and through which an air flow passage extends. A valve member is slidably mounted in the air flow passage and is operable to open and close the through passage. By providing a resilient actuator for displacing the modulator member in a first direction and a stop for arresting the movement of the flow control valve while permitting movement of the modulator valve it is possible to provide for modulated opening and closing of the control valve by balancing the pressure applied by the resilient actuator against the air pressure applied to the modulator member downstream of the through passage.

This invention relates to modulator valves. In particular, this invention 
relates to a pneumatic modulator valve. 
PRIOR ART 
Considerable difficulty has been experienced in attempting to provide an 
inexpensive pneumatic modulator valve which can be used to modulate the 
air flow in a pneumatic system. 
In dump trucks, it is necessary to control the rate at which the hydraulic 
ram is allowed to contract to lower the container body under conditions 
where the load in the container body may vary considerably. Various 
attempts have been made to achieve this controlled lowering by using a 
pneumatic control system for controlling the operation of the hydraulic 
supply control valves, however, difficulty has been experienced in 
providing an effective pneumatic modulator valve for this purpose. 
I have found that these difficulties can be overcome by providing in a 
pneumatic valve, the improvement of a modulator member which is slidably 
mounted in a cylinder and through which the air flow passage extends and 
in which a valve member is slidably mounted so as to be operable to open 
and close the through passage. By providing a resilient actuator for 
displacing the modulator in a first direction and stop means for arresting 
the movement of the flow control valve while permitting movement of the 
modulator valve it is possible to provide for modulated opening and 
closing of the control valve by balancing the pressure applied by the 
resilient actuator against the air pressure applied to the modulator 
member downstream of the through passage. 
According to one aspect of the present invention, there is provided a 
pneumatic modulator valve comprising a housing having a cylinder formed 
therein which has first and second ends, a modulator member slidably 
mounted in said cylinder for movement to a fro between said ends of said 
cylinder, said modulator member cooperating with said housing to form a 
discharge chamber at said second end of said cylinder, resilient actuator 
means operable to apply a pressure to said modulator member to urge it to 
move in a direction from said first end toward said second end of said 
cylinder, an air input passage opening into said housing and through said 
modulator member into said discharge chamber, a valve member carried by 
said modulator member for movement relative to said housing and mounted 
for movement relative to said modulator member between a position closing 
and a position opening said air input passage, valve closure means 
normally urging said valve member to its closed position, means for 
arresting the movement of said valve member with respect to said housing 
while permitting movement of said modulator member so as to cause said 
valve member to move to its open position, said modulator member being 
movable toward said first end of said cylinder when the pressure applied 
to said modulator member in said discharge chamber exceeds the pressure 
applied by the resilient actuator to move said valve member toward its 
closed position.

With reference to FIG. 1 of the drawings the reference numberal 10 refers 
generally to a pneumatic valve constructed in accordance with an 
embodiment of the present invention for use in controlling the flow of a 
stream of air. 
The valve 10 comprises housing 12 which has a lower body portion 12a in 
which cylinders 14 and 16 are formed and an upper portion 12b in which a 
passage 18 is formed. A slot 20 opens from the passage 18 and extends in 
an arcuate path through an angle of about 120.degree.. A flange 22 
projects laterally from the upper body portion 12b and is formed with 
threaded mounting passages 23 which may be used for mounting the valve at 
any required location. A pair of air inlet passages 24 and 26 open into 
the cylinders 14 and 16 respectively. The air inlet passages 24 and 26 
each have an upstream end remote from their associated cylinders 14 and 16 
and a downstream end opening into the cylinders 14 and 16 respectively. 
The inlet passage 26 has a threaded bore. A threaded passage 28 is formed 
in the lower body portion 12a and is located centrally between the 
passages 24 and 26. A valve mounting sleeve 32 has a threaded body portion 
adapted to threadedly engage the threaded bore of the air inlet passage 
26. The sleeve 32 has a through passage 36. A Shrader valve 40 is 
threadedly mounted in the through passage 36 and serves to control the 
flow of air through the passsage 36. The outer end portion 44 of the 
Shrader valve 40 bears against a slide member (not shown) which is 
slidably mounted in the cylinder 16. This mechanism operates in the same 
manner as that described in application Ser. No. 569,654, now U.S. Pat. 
No. 4,526,197, which is assigned to the assignee of the present 
application and will not therefore be described in detail. 
The valve actuator includes an actuator drum 110 which comprises a 
cylindrical body portion 112 within which a boss 114 is formed. A passage 
116 opens outwardly from the boss 114 and a manually engageable lever arm 
118 is mounted in the passage 116 and arranged to extend through the 
arcuate slot 20. The cylindrical body portion 112 has a cylindrical outer 
face 120 which is adapted to fit in a close fitting sliding relationship 
within the passage 18. The drum 110 is rotatable within the passage 18 by 
manually engaging the lever arm 18 and moving it angularly along the slot 
20. The cylindrical face 120 is formed with cam faces 112 and 124. The cam 
face 112 is arranged to be disposed in alignment with the open upper end 
of the cylinder 14 and the cam face 112 is arranged to be located in 
alignment with the open upper end of the cylinder 16. The contour of the 
cam face 112 is illustrated in FIG. 2 of the drawings. 
The structure of the lower body portion 12a in which the cylinder 14 is 
formed is different from that previously described in U.S. Pat. No. 
4,526,197 issued July 2, 1985 to Diesel Equipment Limited, in that the 
inlet passage 24a is not threaded and an air outlet passage 130 opens 
laterally outwardly from the cylinder 14. 
As in application Ser. No. 569,654, now U.S. Pat. No. 4,526,197, the air 
inlet passages 24 and 26 open into the cylinders 14 and 16 respectively 
through a side face 46. A shallow groove 48 is formed in the side face 46 
to receive a sealing ring (not shown). A manifold 52 is secured in a 
face-to-face relationship with respect to the side face 46 by means of a 
mounting screw 54 which threadedly engages the threaded passage 28. An air 
inlet conduit 60 is secured to the manifold by means of a coupling 62. 
As previously indicated, the structure of the piston which is mounted in 
the cylinder 16 is the same as that previously described in application 
Ser. No. 569,654, now U.S. Pat. No. 4,526,197, and will not therefore be 
described. 
With reference to FIG. 2 of the drawings, it will be seen that the 
penumatic modulator valve generally identified by the reference numeral 
132 includes the cylinder 14 which has a first end 134 and a second end 
136. The cylinder 14 has a longitudinal axis 138. The air inlet passage 24 
opens into the first end 134 of the cylinder 14 and is located to 
communicate with the annular recess 156 of the modulator member 140 and 
the air outlet passage 130 opens from the second end 136. The modulator 
member 140 is slidably mounted in the cylinder 14 for longitudinal 
movement in the direction of the axis 138. The modulator member 140 is 
preferably circular in cross-section as is the cylinder 14. The modulator 
member 140 has grooves 142 and 144 located at opposite ends thereof within 
which sealing rings 146 are located which serve to prevent the passage of 
air between the sides of the modulator member and the wall of the cylinder 
14. A bore 148 is formed in the modulator member 140 and extends inwardly 
from the upper end thereof. A metal divider wall 150 is secured in the 
bore 148 against a shoulder 152. The metal divider 150 may be in the form 
of a core plug. The divider wall 150 serves to form a modulator chamber 
154 in the lower end of the bore 148. An annular recess 156 is formed 
about the body of the modulator member 140 and an air input passage 158 is 
formed in the body of the modulator member and communicates with the 
annular recess 156 so as to permit air from the air inlet passage 124 to 
pass to the modulator chamber 154. A modulator output passage 160 is 
formed in the bottom wall 168 of the modulator member and serves to 
communicate between the modulator chamber 154 and the second end 136 of 
the cylinder. A valve member 162 consists of a valve stem 164 which is 
slidably mounted in the modulator output passage 160. A first valve 
closure head 166 is mounted on the upper end of the stem 164 and located 
in the modulator chamber 154. A sealing ring 167 is located on the stem 
164 on the underside of the head 166 and serves to sealingly close the 
modulator output passage 160 when the valve member is located in its 
closed position. A second valve closure member 170 is located at the 
distal end of the stem 164 and a compression spring 172 extends between 
the second valve member 170 and the underside of the bottom wall 168 of 
the modulator member and normally urges the second valve closure member 
170 away from the modulator member, thus tending to locate the first valve 
closure member 166 in a position closing the modulator passage 160. 
A plug 180 is located in the lower end of the cylinder 14 and is sealed 
therein by means of sealing rings 182. A vent passage 184 opens through 
the plug 180 and is axially aligned with the second valve closure member 
170. An O-ring 171 is located in a recess 173 which is formed in the plug 
180 and serves to sealingly engage the second valve closure member 170 to 
close the vent passage 184 when requird in use. When the vent passage 184 
is closed, the second end 136 of the cylinder 14 serves to form a pressure 
chamber in which the pressure in the air line which communicates with the 
output passage 130 will be established. 
A bridge member 185 is formed with a mounting passage 186 through which a 
mounting screw 187 extends to communicate with a threaded passage (not 
shown) formed in the lower face of the housing 12. A stop pin 189 is 
mounted on the bridge member 185 and extends into the cylinder 16 and a 
passage 188 is formed in alignment with the lower end portion of the stem 
164. 
The valve control mechanism generally identified by the reference numeral 
190 includes the actuator 110 previously described together with a 
resiliently compressible valve actuator assembly 200 which includes a ball 
202 mounted for movement along the cam 122. The ball 202 is mounted in a 
dish-shaped recess 204 which is formed in a support 206. The support 206 
has a stem portion 208 and an annular shoulder 210. A compression spring 
212 extends into the bore 148 and bears against the divider wall 150. The 
compression spring 212 is proportioned so as to be partially compressed 
during all positions of the modulator member in use so as to continuously 
apply a load to the modulator member. 
In use, when the lever arm 118 is located in the valve closing position 
illustrated in FIG. 2 of the drawings, the modulator member 140 is located 
in a position such that the modulator passage 160 is closed and the vent 
passage 184 is closed. The loads in the springs 172 and 212 are such that 
the valve stem 162 is fully extended. 
When the lever arm 118 is moved in the direction to effect an opening of 
the valve, the cam 122 will deflect the ball 202 to apply a compressive 
load to the compression spring 212. This load will move the modulator 
member 140 toward the second end of the cylinder 14. The plug 180 prevents 
movement of the second valve closure 170 with the result that the 
modulator member 150 moved relative to the valve closure member 166 to 
open the modulator passage 160. Air is then free to pass from the inlet 
passage 24 through the passage 158 and modulator chamber 154 through the 
modulator passage 160 into the second end of the cylinder 16 and outwardly 
through the output passage 130. The air flow rate can be controlled by 
moving the lever arm 118 to increase or decrease the load applied to 
increase or decrease the clearance between the valve closure member 116 
and the bottom wall 168 of the modulator member. When the air pressure in 
the pressure chamber 136 increases, it will act against the distal end of 
the modulator member 140 and will deflect the modulator member 140 toward 
the first end of the cylinder by compressing the spring 212 to maintain a 
pressure balance. This will cause the modulator passage 160 to be 
restricted automatically so as to automatically maintain the pressure 
balance and thereby maintain a substantially constant pressure downstream 
of the modulator member. The downstream pressure can be varied by 
adjusting the position of the lever arm 118. 
When the lever arm 118 is returned to the closed position, the load applied 
to the modulator member by the spring 212 will be reduced and if the 
pressure in the pressure chamber 136 is maintained, this pressure will 
serve to move the modulator member 140 toward the first end of the 
cylinder until the vent closure member 170 is moved away from the vent 
passage 184 to open the vent passage 184 to vent the air from the pressure 
chamber 136 until the pressure drops to a sufficient extent to permit the 
compression spring 212 to reassert itself and relocate the second valve 
closure member 170 in a position closing the vent passage 184 such that 
when the lever arm 118 is again moved to an open position, the valve would 
operate as previously described. 
An important feature of the present invention is the fact that the 
structure of the valve is simple and inexpensive to manufacture. These and 
other advantages of the present invention will be apparent to those 
skilled in the art.