US3555965A

US3555965A - A apparatus for controlling pressure in a hydraulic machine

Info

Publication number: US3555965A
Application number: US699959A
Authority: US
Inventors: Adolf F Weiss
Original assignee: ALPHA PRESS Co
Current assignee: ALPHA PRESS Co
Priority date: 1968-01-23
Filing date: 1968-01-23
Publication date: 1971-01-19
Anticipated expiration: 1988-01-19

Abstract

Apparatus for controlling the hydraulic pressure in a hydraulic machine, such as a hydraulic press, for enabling the hydraulic pressure to be incrementally increased. A flow control device is provided in the hydraulic circuit of the machine and when the movable member of the machine reaches a predetermined position, it actuates the flow control device. The flow control device initially operates intermittently, with each intermittent operation serving to move a movable member incrementally toward a hydraulic flow blocking position and hence increasing the hydraulic pressure by an incremental amount. Preferably, this is accomplished by an intermittently operated motor which drives a cam that, in turn, moves a valve member toward a flow blocking or closed position. When the hydraulic pressure reaches a preselected amount, the flow control device is operated continuously until the hydraulic pressure reaches a maximum, whereupon no further pressure increase takes place. Once the hydraulic machine has performed its cycle of operations, the flow control device is restored to its original or initial position, ready for a new machine cycle.

Description

i United States Patent [72] lnventor AdolfF.Weiss Easton, Pa.

[Zl] Appl. No. 699,959

[22] Filed Jan. 23, 1968 [45] Patented Jan. 19, 1971 [73] Assignee Alpha Press Company Alpha, NJ.

a corporation of New Jersey [54] APPARATUS FOR CONTROLLING PRESSURE IN Primary Examiner-Everette A. Powell, Jr. Attorney-Roylance, Abrams, Kruger, Berdo & Kaul ABSTRACT: Apparatus for controlling the hydraulic pressure in a hydraulic machine, such as a hydraulic press, for enabling the hydraulic pressure to be incrementally increased. A flow control device is provided in the hydraulic circuit of the machine and when the movable member of the machine reaches a predetermined position, it actuates the flow control device. The flow control device initially operates intermittently, with each intermittent operation sewing to move a movable member incrementally toward a hydraulic flow blocking position and hence increasing the hydraulic pressure by an incremental amount. Preferably, this is accomplished by an intermittently operated motor which drives a cam that, in turn, moves a valve member toward a flow blocking or closed position. When the hydraulic pressure reaches a preselected amount, the flow control device is operated continuously until the hydraulic pressure reaches a maximum, whereupon no further pressure increase takes place. Once the hydraulic machine has performed its cycle of operations, the flow control device is restored to its original or initial position, ready for a new machine cycle.

,1 Presence SWlTCH v SHEEJLOFZ PATENTEDJANISIHYIA APPARATUS FOR CONTROLLING PRESSURE IN A HYDRAULIC MACHINE This invention relates to hydraulic machinery, such as a hydraulic press which includes at least one punch member movable under the influence of hydraulic pressure and more particularly, the present invention relates to apparatus for controlling the hydraulic pressure within such a machine so that such pressure can be selectively increased by incremental amounts.

While the present invention is not limited to any particular type of hydraulic machine, it finds particular utility in connec tion with hydraulic presses of the type which are used for compacting operations. Such presses generally include a pair of relatively movable punch members which are movable relatively toward one another to compact a powder or slurry material deposited in the cavity of a die plate therebetween. Ordinarily, such material is supplied in the form of a slurry composed of approximately 50 percent water and 50 percent powder. A commonly used type of powder is ferrite powde r, such as barium. In one typical type of compacting operation, the bottom punch extends partially into the cavity in a die plate and the slurry is poured into the remainder of the cavity. Then, by hydraulic pressure, the upper punch is lowered into the die cavity to compress and compact the slurry material between the upper and lower punch members. Obviously, in order to provide a satisfactory final product, some means must be provided for removing the water which initially forms about half of the slurry. The commonly accepted and known way of removing such water was to provide a series of small drain bores through the bottom punch member and to apply a vacuum to these drain bores to tend to draw the water out of the slurry during the compacting operation. It was, however, found that this procedure of compacting and water removal was not entirelyysatisfactory. The problem appeared to be in the speed of movement of the upper or movable punch member. If the punch member was moved at low speed to apply a low initial pressure to the slurry, then the pressure of compaction was often offset by leakage in the hydraulic systemitself. That is, at low speeds, the low pressure could not be sustained for any period of time without encountering leakage past the seals in various valves. As a result, in such a system it was often not possible to reach the maximum desired pressure, and as a result, the part or product being formed was not compacted to a sufficient degree. Alternatively, if an attempt was made to solve this problem by moving the upper punch at higher speeds and greater pressures, thereby overcoming the problem of leakage in the hydraulic system, it was found that entry of the upper punch into the die cavity would often tend to force a portion of the slurry out of the cavity. Naturally, in order to make a satisfactory part, the quantity of slurry or powder material must be accurately predetermined, and if even a small portion of this material is forced out of the cavity, then the remaining material will not have a sufficient volume to form a final part of predetermined strength characteristics.

In view of the foregoing considerations, it should be apparent that it would be desirable to provide means for controlling a hydraulic compacting press so that the movable member thereof moves slowly at first so that the water can be removed from this slurry at low pressure, and thereafter, the speed of the movable member is increased to apply maximum pressure to the part being formed. It is a primary object of the present invention to accomplish this beneficial result.

Another object of the present invention is to overcome the difficulties and deficiencies associated with prior art control devices for hydraulic compacting presses," and to provide instead, a new and improved method and apparatus for controlling a compacting press to assure that complete water removal from the slurry can be accomplished without in any way diminishing the maximum compacting pressure which is ultimately applied to form the part.

Another object of the present invention is to provide a method and apparatus'for controlling the hydraulic pressure in a hydraulic machine so that such hydraulic pressure can be incrementally increased in a controlled manner.

Another object of the present invention is to provide a simple and efficient pressure control device for a hydraulic apparatus, such as a hydraulic press.

Another object of the present invention is to provide a method and apparatus for progressively increasing the hydraulic pressure in a hydraulic circuit by incremental amounts until such pressure reaches a preselected amount and thereafter, for continuously increasing the pressure until a predetermined maximum is reached.

Another object of the present invention is to provide a-simple form of flow control device which can be readily installed on any existing type of hydraulic press, without the need for substantially modifying or revising such press, and which, when so installed, serves as a control device for the hydraulic pressure which operates the press.

Other objects, advantages, and salient features of the present invention will be apparent from the following detailed description which, taken in conjunction with the annexed drawings, discloses a preferred embodiment thereof.

The foregoing objects are attained by providing a flow control device which includes a movable valve member interposed in the hydraulic circuit of a hydraulically operated machine, such as a hydraulic press. A cam member is provided for gradually moving the valve member toward a flow blocking position and as the valve member is so moved, it tends to increase the pressure in the hydraulic system itself. The cam is driven by a drive motor which itself is intermittently operated initially in response to a signal from the press or machine, such signal being generated responsively to movement of a movable member thereof, such as a punch. As a result, when the motor is operated intermittently, the cam is rotated or moved intermittently, and the valve member is intermittentl y advanced toward a flow blocking position. Each intermittent advance of the valve member causes a corresponding pressure increase in the hydraulic circuit of the apparatus, and once the pressure reaches a predetermined or preselected amount, then the motor operates continuously until the valve reaches its maximum flow blocking position and hence, the pressure in the system reaches a maximum amount. Thereafter, the hydraulic machine performs its cycle of operations, and as such cycle is completed, the motor is once again operated to restore the flow control device to its initial position, ready for a new cycle of machine operation.

Referring now to the drawings:

FIG. 1 is diagrammatic view, partly in section, showing the basic components of a hydraulic press;

FIG. 2 is a elevational view, partly in section, of a flow control device in accordance with the principles of the present invention;

FIG. 3 is a sectional view taken substantially along the line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken substantially along the line 4-4 of FIG. 2; and

FIG. 5 is a schematic wiring diagram showing a suitable control circuit for use with the flow control device of the present invention.

Referring now to the drawings in greater detail, there is shown in FIG. 1 the operating portion of a suitable hydraulic machine generally designated 10 which is advantageously of the hydraulic press type. Such a hydraulic machine includes a press table 12 which is normally fixed in position and which carries an upstanding punch member 14 thereon. The punch 14 forms the lower punch in the machine 10. An upper platen 16 carries a depending punch member 18, axially aligned with the punch member 14, and forming the upper punch member for the machine. The upper platen 16 is supported by an operating rod 20 which can advantageously be the piston rod of a hydraulic cylinder and piston arrangement utilized for moving the punch member 18. A lower platen 22 is provided beneath the press table 12 and is supported by a suitable operating rod 24 which again can advantageously form the piston rod of a hydraulic cylinder and piston arrangement. Upstanding rods or support members 26 extend from the lower platen 22 through the press table 12 and support thereupon, a

die case or die plate 28 having a central bore 30 extending therethrough in alignment with the punches l8 and 14, thereby serving to form the cavity for the machine.

As will be apparent, movement of the lower platen 22 causes a corresponding movement of the die case 28. Hence, as the die case 28 is moved toward or away from the press table 12, the lower punch 14 will move further into or out of the cavity or bore 30, thereby changing the volume of this cavity. Thus, by properly adjusting or controlling the degree of movement of the operating rod 24, the positioning of the die case 28 will be very precisely controlled, and hence, the volume of the cavity 30 will be accurately predetermined. In my copending application Ser. No. 649,252, filed June 27, 1967, now U.S. Pat. No. 3,430,538 dated March 4, 1969, there is described the method and means for controlling the movement of the operating rod 24.

Once the die case 28 has been moved or adjusted relatively to the press table 12 by controlling the degree of movement of the operating rod 24, the volume in the cavity 30 will be determined by the amount of space between the top of the lower punch member 14 and the top of the die case 28. This cavity is then filled with a suitable slurry material out of which the article is to be finally formed. Then, by operation of the upper operating rod 20, the upper platen l6 and the punch 18 carried thereby is lowered toward and into the cavity, to compress and compact the slurry material therein between the confronting surfaces of the

respective punch members

14 and 18. By varying the shape or configuration of the punch members, or of the cavity, the shape of the final article can be suitably varied. in my copending application Ser. No. 601,791, filed Dec. 14, 1966, now US. Pat. No. 3,407,710, dated Oct. 29, 1968, there is described a suitable means for controlling the stroke of the cylinder and piston arrangement which advantageously mounts the upper operating rod 20.

As described hereinbefore, the slurry material which is introduced into the cavity contains a substantial amount of water and it si necessary to drain this water from the slurry during the compacting operation. A series of drain bores 32 are drilled through the lower punch member 14 and such bores communicate with a conduit means 34 which can direct the removed water to a suitable reservoir. While the conduit means 34 can be, and advantageously is, connected to a suitable vacuum source to speed the removal of the water from the slurry, it has been found that the present invention accomplishes removal of the water from the slurry even if no vacuum is applied to the conduit means 34.

it will, of course, be understood that the hydraulic machine includes a suitable hydraulic operating circuit and while there are any number of suitable types of hydraulic operating circuits which can be utilized for hydraulic presses and hydraulic machines of this general type, this specific circuit does not form any part of this invention and hence, need not be described in detail herein. Instead, it is sufficient to state that the hydraulic operating circuit for the machine 10 includes at least the cylinder and piston arrangement which drives the piston rod for moving the upper punch and the upper platen. Within this operating circuit, a suitable flow control device is provided for the purpose of accomplishing the objectives of the present invention and such a flow control device is shown in FIG. 2 and is generally designated 36. The operating circuit or wiring diagram forming a part of this flow control device, and utilized in conjunction therewith, will be described hereinafter in connection with FIG. 5. The flow control device 36 includes a frame means having a pair of spaced apart support walls 38 and 40 joined at one end by an end wall 42. 1f desired, suitable intennediate support columns,

not shown,'-can beprovided betweenthe support walls 38 and to assure that the same remain fixed in their proper positions.

The flow control device includes a flow valve means generally designated 44 which is connected to the end wall 42 by any suitable type of attachment means. The valve means 44 includes a body 46 having a longitudinal bore 48 extending therethrough and having an angularly extending bore 50 likewise extending therethrough and intersecting with the bore 48. A sleeve member 52 is. mounted in the bore 48 to form a seat for a movable valve member 54 having a conical end which seats against the sleeve 52. The valve member 54, as can be seen, is slidably mounted within the bore 48 and is urged toward a closed or seated position by a spring member 56.

As aforementioned, the flow control device 36 is interconnected in the hydraulic circuit of the machine and the flow through the valve means 44 thereof is in the direction shown by the arrows of FIG. 2. That is, the flow initially enters the bore 48, flows through the sleeve 52 and then exhausts from the valve through the bore 50. The spring 56 normally urges the movable valve member 54 toward its closed or flow blocking position while the flow of hydraulic fluid is in the opposite direction tending to move the valve member 54 away from the sleeve 52 toward its open position. Thus, it will be apparent that the stronger the pressure of the spring, the greater the pressure on the hydraulic fluid will have to be in order for such hydraulic fluid to flow through the valve means 44.

An adjustment plunger 58 is mounted within an adjustment nut 60 and the plunger and nut arrangement serve to accurately control the degree of compression of the spring 56 and hence controls the force which the spring applies upon the movable valve member 54. An end of the plunger projects as the rod 62 beyond the nut 60 and hence forms a projecting element at one end of the valve means 44. At its opposite end, the rod 62 carries a forked or bifurcated member 64 which carries an upstanding rod 66 which projects between the forked portions and considerably thereabove. An elongated slot 68 is provided through the support wall 38 so that the rod 66 can project therethrough. The roller 70 is rotatably mounted on the rod 66 between the arms of the forked members 64 and is hence aligned with the actuator rod 62 for the valve means 44.

As can be seen from FIG. 2, the slot 68 is elongated suffrciently to permit a considerable degree of lateral movement of the projected rod 66. At one end of the slot 68, a switch 72, preferably of the limit switch type, is mounted so that the plunger 74 thereof is only engaged when the rod 66 reaches the end of its travel, at the forward portion of the slot 68.

A cam shaft 76 is also provided in the flow control device 36, journaled at its opposite ends in bearings 78 carried respectively by the support walls 38 and 40. The cam shaft 76 carries centrally thereupon, an eccentric cam member 80 of a predetermined configuration, one such suitable configuration being shown in FIG. 3. At one end, the cam shaft 76 is coupled with a drive shaft 82 extending from a gear box 84. The gear box, in turn, is operated by an impulse driven motor 86 which, in operation, imparts a rotational movement to the cam shaft 76.

Finally, the cam shaft 76 additionally carries a homing cam 88 which is a segmental type of cam whose configuration can best be seen from FIG. 4. Cam 88 is arranged to energize or actuate a limit switch 90 mounted upon the support wall 40 once during each complete rotation of the cam shaft 76.

Referring now to FIG. 5, there is shown therein one suitable form of operational control circuit or wiring diagram to be utilized in conjunction with the flow control device 36 previously described. The wiring diagram includes a main on-ofi switch 92 which consists of a ganged series of three

separate switches

94, 96 and 98. Additionally, it includes a control relay 100 which operates a pair of ganged

switches

102, 104. Finally, an adjustable timer means 106 is provided, with such 'timer means including an adjustable on cycle and an ad- 75 signal generated shortly before the upper punch 18 enters the die cavity 30.-Assuming that the main switch 92 in the circuit is in a on" position, as indicated in P10. 5, the signal A is transmitted through a wire 110 across the switch 94 and through a wire 112 to thecontrol relay 100. Additionally, the signal from thewire 110 is transmitted through a line 114 and across the normally closed switch 116 forming a part of the switch member 72. The switch 116 is ganged or coupled with a further switch 118 whose function will be presently described. As the current continues across the switch 116 and alongthe line 114, it is supplied to the timer 106 and also to a blue control signal light 120. This signal light indicates that power is being supplied to the timer and the control relay.

As briefly mentioned hereinabove, the timer is provided with both an adjustable "on and an adjustable off cycle. Preferably, each of these cycles is adjustable between 0 and seconds and if it assumed that each cycle isadjusted to 5 seconds, then the timer, will be "off for 5 seconds, then "on" for 5 seconds, then off. again for 5 seconds, and so on in an intermittent manner. One suitable formof timer of this type is sold commercially by Timeco, lncl'of Huntington, West Virginia, under the designation Model 04.

When the timer 106 switches to its .on cycle it closes the switch 122 associated therewith and supplies current through a line 124 to the motor 86. it simultaneously energizes a green control signal light 126. As previously explained, operation of the motor 86 rotates the cam shaft 76 and hence rotates the earns 80 and 88 carried thereby. The motor 86 will only operate so long as the timer 106 is -in.its"on" cycle, since as soon as the timer is switched to its off cycle, the switch 122 is moved from its closed position to its open position as shown v in FIG. 5. Thus, it' will bev understood that the motor 86 is operated in an intermittent manner and tliat the shaft 76 is thus rotated intermittently thereby advancing the earns 80 and 88 intermittent. As the cam 80 rotates in an intermittent fashion it contacts the roller 70 and applies a pressure thereto which pushes on the shaft 62 and thereby increases the pressure of the spring 56.- Since the spring pressure on the movable valvemember 54 is increased, the pressure in the hydraulic circuit of the machine is necessarily increased since it becomes more and more difficult to open the valve 54 to permit the flow from the conduit 48 to the conduit 50. As the pressure in the hydraulic circuit increases, the pressing force applied to the slurry contained within the cavity is also increased, with such increase being small increments.

Again as shown in FIG. 1, an adjustable pressure switch 128 is provided in association with the machine hydraulic circuit, and in particular, with the hydraulic cylinder and piston arrangement which moves the punch-member 18. This pressure switch can be adjusted to any predetermined amount,. and when the pressure has been incrementally increased to this amount, a signal B is generated. As shown in F IG. 5, this signal B comes across a line 130, across the switch 96 and across the normally closed switch 118 forming 'a part of the switch means 92. The control relay 100 will have closed the switch 102 against the contact 132 in response to the signal A which had previously received and hence the current supplied along the line 30 can continue across the switch 102 and across a line 134 to the timer switch 122. From there, the current flows across the closed timer switch 122 and-through the line 124 to the motor 86 to cause the same to drive continuously. This continuous driving will take placeuntil the high spot on the cam 80 contacts the roller 70. At; this time, the forked assembly 64 and the roller 70 will be advanced their maximum position toward the valve means 44 and the rod 66 will be ad-' vanced in theslot 68 untilit contacts the plunger 74 of the switch 72. At this time, the normally closed switches 116 and 118 which comprise the switch 72 will be opened and current to the motor 86 will be interrupted. At this time, the maximum pressure will be exerted in the hydraulic circuit, although, if desired, a separate force adjusting valve, not shown, can be provided in the circuit so that the circuit pressure will never exceed a maximum preselected amount.

It will be understood from the manner of operation set forth thus far that punch 18 enters the die cavity at a low pressure. This pressure is then incrementally increased until a preselected value is reached whereupon the pressure is thereafter increased continuously until a preselected maximum is reached. The incremental pressure increase serves to compress the slurry to remove the water therefrom and the maximum pressure applied continuously is utilized for forming the part between the

punches

14 and 18 Once the compacting operation has been completed, and the punch 18 and platen 16 are raised, the signal A is shut off. When this occurs, the control relay resets to the position shown in FIG. 5. Additionally, constant voltage C either from the machine or from some suitable external source is applied across a wire 136, through a wire 138, across a normally closed switch forming one of two switches in the switch means 90 and across the wire 142 to the normally closed switch 104 in the control relay. This current then flows-from the switch 104 through a line 144,.through the "on switch 98 and through a line 146 which connects with the line 124. As a result, this constant voltage feeds back through the line 124 to the motor 86 to drive the same continuously until the cam 88 contacts the switch 90. While this is occurring, a portion of the current from the line 138 feeds across the other switch 148 forming a part of the switch means 90 to energize a red control light which indicates that the apparatus is returning to its home" position. When the cam 88 contacts the switch 90, the home" position is reached and the

switches

140 and 148 are opened. This cuts off all current to the motor 86, and at this time, both of the cams will have been returned to their initial position, all of the circuit components will have been returned to their initial positions, the punches will have been returned to their initial positions, and the entire apparatus will be ready for a new machine cycle.

If the flow control device selector switch 92 is moved to a off position, then all of the

switches

94, 96 and 98 will be moved from their on" positions, as shown in FIG. 5 to a of position and the circuit will operate in the following manner.

.The current feeding through the line 1306 will be transmitted through a branch line 152 to the' of "terminal for the switch 98. Since the switch 98 will be in the off position, the current will feed through the switch 98 through the line 146 and back through the line 124 to operate the motor 86. The motor will rotate the cam shaft and the cam 80 until the high spot on the cam causes the operating rod 66 to energize the switch 72. At this time, theindividual switches l 16 and 1 18, which comprise the switch means 72, will be opened and the entire control unit 36 will be taken out of operations so that it does not interfere with the main machine. Of course, when it is desired to place the pressure control unit 36 back into operation in the system, one need only to turn the switch means 92 from its of position to its on" position.

It should be apparent after reading the foregoing detailed description that the present invention provides a unique method and means for enabling the movable punch member to be introduced into the cavity at low pressure, with the pressure thereafter being progressively increased by small incremental amounts. In practice, it has been found that incremental pressure increases of between 5 and 10 p.s.i. provides satisfactory results. These incremental pressure increases will serve to remove the water from the slurry and exhaust the same through the drain conduit 34, even if no vacuum is applied to this conduit. Of course, a vacuum can be used, if desired, since this will merely speed up the operation of extracting the water from the slurry. When a preselected amount of pressure has been applied incrementally, the system will operate continuously to increase the pressure to a predetermined maximum amount. This maximum pressure is utilized for compacting the slurry within the cavity for forming a final part of desired strength characteristics.

While the invention described in the foregoing detailed description and shown in the appended drawings, which form a part of this specification, accomplishes the objectives set forth at the outset hereof, it will be understood that various other changes and modifications can be made without departing from the scope of the invention as defined in the appended claims.

lclaim:

1. In a fluid operated apparatus which includes at least one movable member and a fluid pressure system which applies pressure to said member to effect the movement thereof, the improvement for enabling said member to be moved both incrementally and continuously, as selected, which comprises:

flow control means in said fluid pressure system;

said flow control means including at least one movable portion movable toward a flow blocking position;

movable force applying means for operatively engaging said movable portion;

drive means for moving said movable force applying means;

drive control means responsive to a signal generated pursuant to movement of said movable member for intermittently actuating said drive means;

said drive means thus intermittently moving said movable force applying member which in turn intermittently moves said movable portion toward said flow blocking position; and

each intermittent movement of said movable portion toward said flow blocking position correspondingly increasing the pressure in said fluid pressure system, thereby causing said pressure to increase in progressive increments.

2. The improvement defined in claim 1 wherein said movable force applying means includes a cam member and wherein said drive means includes a motor for moving saidcam member.

3. The improvement defined in claim 2 further including first switch means and switch actuating means coupled with said movable portion, said switch actuating means engaging said first switch means when said cam displaces said movable member its maximum degree of movement.

4. The improvement defined in claim 3 wherein said first switch means is operatively coupled with said motor and wherein, when said first switch means is actuated by said switch actuating means, said motor is driven continuously until the fluid pressure in said system reaches a predetermined maximum amount.

5. The improvement defined in claim 4 further including second switch means and segmental cam means operated by said motor to engage said second switch means when said cam member reaches its initial position, thereby restoring said How control means, drive means and drive control means to their initial positions, ready for a new cycle of operations.

6. In a fluid operated apparatus which includes at least one movable member, a fluid pressure system which applies pressure to said member to effect movement thereof, and a flow control means in said fluid pressure system, the improvement for enabling said member to be moved both incrementally and continuously, as selected, which comprises:

a flow line in said fluid pressure system having a valve seat therein;

movable valve means in said flow line, including a valve member and biasing means urging said valve member toward said valve seat to block flow through said flow line;

said movable valve means also including a projecting plunger operatively engaged with said biasing means;

a rotatable shaft having a cam member thereon, said can] member being engageable with said plunger as said shaft rotates;

drive motor means for rotating said shaft;

drive motor control means operable responsively to a signal generated pursuant to movement of said movable member for intermittently operating said drive motor and hence for intermittently rotating said shaft and said cam member; and said cam member rotation engaging said cam member against said plunger so that each intermittent cam rotation causes said plunger and hence said valve member to move toward said valve seat, thereby causing the pressure in said fluid pressure system to increase in progressive increments.

7. The improvement defined in claim 6 further including first switch means operatively coupled with said drive motor and a switch actuating element projecting from said plunger to engage said first switch means when said cam member moves said plunger its maximum degree of movement toward said valve seat, said first switch means, when engaged by said actuating element, causing said drive motor to drive continuously until said fluid pressure in said system reaches a predetermined maximum amount.

Claims

1. In a fluid operated apparatus which includes at least one movable member and a fluid pressure system which applies pressure to said member to effect the movement thereof, the improvement for enabling said member to be moved both incrementally and continuously, as selected, which comprises: flow control means in said fluid pressure system; said flow control means including at least one movable portion movable toward a flow blocking position; movable force applying means for operatively engaging said movable portion; drive means for moving said movable force applying means; drive control means responsive to a signal generated pursuant to movement of said movable member for intermittently actuating said drive means; said drive means thus intermittently moving said movable force applying member which in turn intermittently moves said movable portion toward said flow blocking position; and each intermittent movement of said movable portion toward said flow blocking position correspondingly increasing the pressure in said fluid pressure system, thereby causing said pressure to increase in progressive increments.

2. The improvement defined in claim 1 wherein said movable force applying means includes a cam member and wherein said drive means includes a motor for moving said cam member.

5. The improvement defined in claim 4 further including second switch means and segmental cam means operated by said motor to engage said second switch means when said cam member reaches its initial position, thereby restoring said flow control means, drive means and drive control means to their initial positions, ready for a new cycle of operations.

6. In a fluid operated apparatus which includes at least one movable member, a fluid pressure system which applies pressure to said member to effect movement thereof, and a flow control means in said fluid pressure system, the improvement for enabling said member to be moved both incrementally and continuously, as selected, which comprises: a flow line in said fluid pressure system having a valve seat therein; movable valve means in said flow line, including a valve member and biasing means urging said valve member toward said valve seat to block flow through said flow line; said movable valve means also including a projecting plunger operatively engaged with said biasing means; a rotatable shaft having a cam member thereon, said cam member being engageable with said plunger as said shaft rotates; drive motor means for rotating said shaft; drive motor control means operable responsively to a signal generated pursuant to movement of said movable member for intermittently operating said drive motor and hence for intermittently rotating said shaft and said cam member; and said cam member rotation engaging said cam member against said plunger so that each intermittent cam rotation causes said plunger and hence said valve member to move toward said valve seat, thereby causing the pressure in said fluid pressure system to increase in progressive increments.