US2491402A

US2491402A - Hydraulic system

Info

Publication number: US2491402A
Application number: US615314A
Authority: US
Inventors: Warren R Tucker
Original assignee: HPM Development Corp
Current assignee: HPM Development Corp
Priority date: 1945-09-10
Filing date: 1945-09-10
Publication date: 1949-12-13
Anticipated expiration: 1966-12-13

Description

Dec. 33, 1949 w; R. TUCKER HYDRAULIC SYSTEM i zsneets-shet Filed Sept. o, 1945 Patented Dec. 1 3, 1949 HYDRAULIC SYSTEM War-ren R. Tucker, Dayton, Ohio, ::Signor to H-P-M Development Corporation, Winnington, Del., a corporatlon of Delawa'e f Application September 10, 1945, Serial No. 615.314

sclaims. (Ci. 60-52 l This invention relates to hydraulic systems and i is particularly concerned with an improved hy- 'for a machine tool in a single panel.

It is a particular object oi' the present invention to provide an operating and control circuit for a hydraulically actuated machine tool in which the speed oi' the driven member is controlled at a first and a second rate in at least one direction of travel thereof.

It is still another object to provide a control circuit for a hydraulically actuated ram which provides for a rapid traverse, a feed movement and a rapid retraction and accomplishes this by single control valve.

It is still another object to provide a control system for a hydraulically actuated ram which includes a rotary pilot valve which is always indexed in the same direction of rotation.

Still another object is to provide a hydraulic system 'for actuating a fluid motor. a single valve means responsive to the discharge pressure of the fluid source, to the rate oi discharge rrom the fluid motor and to manual means for varying the supply oi fluid from the source to the motor.

Another object is to provide afluid`operable control system for controlling the actuation of a hydraulically operated system in which a single valve is operable from a plurality of stimuli for controlling the driven member.

These and other objects and advantages will become more apparent upon reference to the following description taken in connection with the accompanying drawings in which:

. Figure 1 is a diagrammatic view of a machine tool Operating and control circuit according to this invention: f

Figura 2 is a view showing the Operating mechanism !or the rotary pilot valve oi' ei i:

Figure 3 is 'a section taken on the'f V 3-3 o! Figure 1 showing the rotary valve member in elevation;

Figure 4 is an enlarged view showing one of the valves of the control system oi Figure 1: and

Figura 5 is a i'ragmentary view showing another form of pilot valve. v

General arrangement 'According to this invention a reciprocating ram has connected therewith a fluid source, preferablyja' one way constant delivery pump. Inthe 'motor and pump is the operat- 2 ing and control system according to this invention.

The control system comprises a panel within which is mounted a tour-way valve to direct fluid to one or the other or to both sides of the reci procating ram.

Fluid operable means are provided for moving the four-way valve into its several positions and a rotary pilot valve is provide for directing pressure fluid from the pump to the said fluid operable means.

The rotary valve is characterized by being rotated in the same direction throughout a complete cycle of operations so that it is' not necessary to turn the valve member through other Operating positions to recommence a cycle.

The speed of the reciprocating ram in at least one direction ot movement, the discharge pressure of the pump, and the supply of fluid from the pump to the four-way valve is controlled by a single poppet type valve connected with the pump discharge side and adapted tor actuation by a plurality of stimuli.

According to the preferred form of this invention there i providedmeans operated by the reciprocation oi' the fluid operable ram tor indexing the rotary pilot valve in one direction through its several positions.

structure! arrangemeat Reierring to the drawing, there is shown a motor at to which includes a double acting ram l2. The motor o is connected by conduits M and s with the passages ll' and s' in a block !8. The passages lead to the service ports oi' a four-way valve which includes the reciprocating valve member 20. The four-way valve receives pressure fluid through passage 22 which is connected by a conduit 22' with the discharge side of a pump 24 which 'is prei'e'abiy oi the constant deliv ry yp The pump draws fluid from a reervoir 20 through a. conduit :I while the reservoir receives exhaust fluid from a conduit u.

The opposite ends of the valve member 20 are shouldered to receive the

pistons

32 and 34 which are slidable in the cylinders 35 and 38 which comprise the Operating chambers for the valve member 20. When both or the said cylinders are subiected to fluid pressure, the pistons 32 and u bottom therein and hold the valve member 20 in its Figure 1 position; When one oi' the cylinders 38, :a is exhausted, the pressure in the other thereof hearing on the end of the valve member, moves it into position to direct the pump discharge to one side of the ram az while exhausting the other side thereof.

Fluid is conducted to the cylinder 36 by a. passage 40 in the block !8 and, to the cylinder 38 through passage 42. The passages lead to two of the ports of a rotary pilot valve generally indicated at 44 which comprises the diametrically opposite exhaust ports 46 and a plurality of pressure ports 48 disposed at 60 on either side thereoi and on the same level. The pressure ports 68 are connected with a groove 56 to receive pressure fluid from the passage 22, while the exhaust ports 46 are connected by a passage 52 with the exhaust Conduit 36.

The exhaust from the right end of the fourway valve is lead through passage 54 to the conduit 36 to provide for a free discharge of the advancing side of the ram 62. The exhaust from the left end of the four-way valve is conducted through a passage 56, which includes anadjustable choke member 58, to the exhaust conduit 36.

The discharge side of the pump is connected by passage 22 and passage 66 with the lower side of a valve member 62 which, when moved upwardly connects the pump with the exhaust condu't 30.

The valve member 62 comprises a reduced passage 64 which opens into a chamber 66 above the said valve member. The chamber 66 also houses spring 68 which urges thevalve member downwardly to close off communication between the

passages

60 and 36. The area of the valve member 62 in the chamber 66 is greater than the area thereof exposed to the pressure in passage 66. Therefore, when the pres'sures are the same on both sides of the valve member, it remains seated. However, if the chamber 66 is exhausted, the valve member moves upwardly, the reduced passage 64 preventing the immediate replenishing of the pressure above the said valve member.

The chamber 66 is connected with one side of a valve at which, when manually actuated, is operable to connect the said chamber with exhaust to permit the pressure standing beneath the valve member 62 to move it upwardly, thereby to bypass the pump discharge to exhaust.

The chamber 66 is also connected with a normally closed valve at '12 which is responsive to a predetermined pressure in the passage 66 for connecting the said chamber with exhaust. The valve 12 provides means responsive to a predetermined discharge pressure of the pump for bypassing at least a portion of the pump discharge thereby to control the maximum discharge pressure' of the pump. I

The chamber 66 is also connected with a normally closed valve at '14 which is responsive to a predetermined pressure in the passage 56 ahead of the choke 58 for connecting the said chamber with exhaust. The valve 14 thus provides means responsive to the pressure drop across the choke 68 and, therefore, to the speed of the ram z for b r-passing at least a part of the pump discharge to exhaist to control the speed of the ram I2.

The mecham'sm for indexing the rotary pilot valve is more particularly shown in Figure 2 wher-ein there is shown connected with the valve Operating shaft 16, a knob 18 :for manual actuation, a detent mechanism at 80 for releasably retaining the valve in its several positions, and a ratchet wheel at 82 having as many teeth as there are valve positions.

The plunger l2 carries a rod 84 which adjustably mounts a pair of

identica pawl mechanisms

86 and 66 which are adapted for operative engagement with the ratchet wheel 62 when the ram. fi2 moves leftwardly. There is a third pawl at %adapted for actuating the ratchet wheel 82 as the plunger !2 approaches its retracted posltion and the collar 92 engages the arm 94. The pawis at 86, 88 andao are thus adapted for actuating the ratchet wheel 82 and therethrough the pilot valve in one and the same direction by increments of 60. The collar 92 may be adjusted out of operative positions in order to give a semi-automatic cycle when desired.

Figure 5 shows' a' modifed arrangement of the pilot valve which comprises an open center fourway valve at !66 which is centered by the springs &62 and !64 to connect the pressure line !66 with both of the conduits 48 and 42 leading, respectively, to the

Operating chamber

36 and 38. The valve member of the valve !60 may be moved leftwardly by the solenoid !63 and rightwardly by the solenoid 6, the energization of these solenoids being preferably accomplished by the reciprocation of the ram !2.

operation In Figura 1 the parts are shown in their fast approach position. The pump discharge is directed to both sides of the'ram !2 and there is no exhaust from the motor.

After the ram has advanced a predetermined amount, the pawl 86 actuates the ratchet wheel 82 and the valve 44 to move 60 counterclockwise so 'that the right end Operating chamber of the valve member 20 is connected to drain. The valve member therefore moves rightwardly and the left end of the motor n is connected with the exhaust while the pump delivery is directed to the right end thereof.

The exhaust fluid of the motor o passes through the choke 58 and a pressure is thereby created which urges the valve 14 rightwardly. When the aforementioned pressure reaches a predetermined value, indicating that the ram !2 is Operating at a certain preselected speed, the valve 14 shifts rightwardly to exhaust the chamber 66* above the poppet 62 thereby permitting the lat'- ter to lift and to exhaust at least a portion of the pump discharge to the conduit 30. A condition of balance is quickly reached and the motor speed is thus maintained between close limits atany desired value. After a predetermined further advancing movement of the ram !2, the pawl at 88 engages the ratchet wheel 82 and indexes it together with the valve 44 another 60 counterclockwise so that the., right hand Operating chamber 36 of the valve member 20 is connected to pump pressure while the left hand Operating chamber 38 is connected to drain. The valve member 20 then shifts leftwardly so that the entire pump discharge is directed to the retraction area of the ram |2 while the advancing area thereof is connected with drain and ram |2 moves rapidly rightwardly.

As the ram |2 approaches its retracted position, if the collar 62 is adjusted not to engage the arm 94, the ram bottoms in its cylinder and the subsequent increase in pump pressure lifts the valve 12 against its spring, exhausting the chamber 66 and permitting the pump to bypass to exhaust.

In this event a new cycle may be started by turning the knob 18 clockwise 60'.

If the collar 92 is adjusted to strike the arm 94, then the pawl at 90 is actuated to engage the ratchet wheel 82 to index it, together with the

valve

44, 60 counter-clockwise to place the valvez' in its Figure 1 position to recommence a cycle. In

rection.

The pump may be unloaded freely to drain at any time by moving the valve 10 to exhaustthechamber 66.

It will be apparent from the foregoing that this invention has, among others, the following features:

First, the rotary pilot valve is adapted always to turn the same direction, thereby eliminating the necessity of returning the valve past other Operating positions in order to recommence a cycle.

Second, the four-way valve 20, in its center po sition, provides for a rapid traverse of ram I2 instead of being in a blocking or unloading position as is usual;

Third, the same valve, 62, provides for relief of pressure, flow control and for starting and stopping' of a cycle. This is accomplished by the provision of the three separate actuating valves therefor, one of which is responsive to manual actuation, another of which is responsive to the discharge pressure of the pump, and the last of which is responsive to the speed of the motor by means of the choke valve 58. i V

Fourth, the system is so arranged that, during the working stroke of the ram !2, a back presi sure is maintained thereon so that the operation of the ram is stable and it has no tendency to jump 'ahead when reaching spots of low resistance or when completing the work.

Further, the system of controlling the speed of the motor by unloadin'g the discharge' of the pump provides for a' system having high efllciency, relatively small loss of power resulting from this arrangement.

It will be apparent that various adjustments could be provided for in the control panel. For example an adjustment of the tension on the spring of the

valves

12 and 14 would provide for variations in the maximum pressure and also for an additional adjustmentof the speed of the motor lil over that provided by the adjustable choke at 20.

. e i pass the delivery of said source; and a third control valve responslve to a predetermined pressure between said motor outlet and exhaust for at least partially exhausting said fluid operable means and thereby to by-pass at least a part oi the delivery of said source.

2. In a hydraulic system a fluid motor having an inlet and an outlet; a fluid pump of substantially constant delivery connected to supply said inlet; a poppetvalve having one side connected with said pump and being movable to connect said pump with exhaust; a restricted passage connecting the other side of said valve with said one side, the said other side being larger than said one side for normally urging said valve closed responsive to equal pressures on either side thereof; 'a first. valve manually operabie to exhaust said other side and thereby to by-pass substantially the whole of said pump delivery; a second valve responslve to a predetermined pump i discharge pressure for exhausting said other side While the four-way valve is shown mounted in the panel, `it will be understood that the control and Operating circuits could be otherwise arranged if found more convenient.

It will be' understood that various modifications and arrangements in structure could be made without departing from the spirit of my invention and, accordingly, I desireto comprehend such modiflcations and substitutions of equivalents as may be considered to come within the scope of the appended claims.

I claim;

1. In a hydraulic system; a fluid motor having an inlet and an outlet; a fluid source of substantially constant delivery connected with said inlet; fluid-restricting means connected between said outlet and exhaust tor maintaining a pressure in' said outlet when connected with exhaust substantially proportional to the rate of flow therethrough; a valve connected on one side with said source and on the other side with exhaust; fluid operable means urging said valve to a closed position interrupting communication between said source and exhaust; a first control valve manually operabie for'exhausting said fluid operable means to by-pass substantially the complete discharge of said source; a second control valve responsive to the discharge pressure of said source for at least partially exhausting said fluid operable means thereby to at least partially by- 75 nec to by-pass at least a part of the delivery of said pump; and a third valve responsive to a predetermined pressure at said motor outlet for exhausting said other side to by-pass at least a part of said pump delivery, there being a flow restricting means serially connected with said motor outlet. 4

3. In a hydraulic system; a reciprocable plunger having a main area and a difierential area; a fluid source; a reversing valve movable to connect said source with both of said areas for rapid advance of said plunger, or with said main area for a feed stroke oi said plunger, or with said difierential area for a retraction stroke of said plunger, fluid operabie means for actuating said valve; a rotary pilot valve movable into a first position to supply both of said fluid operabie means to move said reversing valve to its first mentioned position or, into a second position for supplying one of said fluid operabie means to move said reversing valve into its second mentioned position or, into a third position to supply the other of said fluid operabie means for moving said reversing valve intoAts last mentioned position; and indexing means operabie in both directions of movement of said plunger for actuating said pilot valve through its several positions in one and the same direction for a complete cycle of operation.

4. In a hydraulic system; a reciprocable plunger; a fluid source; valve means connecting said source with said plunger and movable into' a plurality of positions for efiecting the rapid ad-` vance, the feed and retraction strokes thereof; fluid operabie means for actuating said valve: rotary pilot means movable to supply fluid to said fluid operable means; means to position said pilot means initially for the rapid advance of said plunger means responsive to a predetermined advancing movement oi! said plunger to index said pilot means in one direction tor initiatinz the the same direction to again inltiate the advancing movement of said plunger in response to a predetermined retracting movement thereof.

5. In a hydraulic system; a reciprocable plunger having a main area and a difierential area; a fluid source; a reversing valve movable to con;

t said source with both or said areas for rama- &seas

advance of said piunger, or with said main area. for a feed stroke of said piunger. or with said difierentia area for a retraction stroke of said piunger, fluid operable means for actuating said valve; a `rotary pilot valve movable into a first position to supply both of said fluid operable means to move said reversing valve to its first mentioned position or, into a second position for supplying one of said fluid operable means to move said reversing valve into its second men tioned position or, into a third position to supply the other of said fluid operable means for moving said reversing valve into its last mentioned position; a ratchet on said pilot valve; a pair of spaced pawls carried by said plunger and operable during the advancing movement thei-cof for engaging said ratchet and actuating said pilot valve into its second and third positions respectively; and a third pawl also carried by said plunger and operable during the retraction stroke thereof for engaging said ratchet and actuating said pilot valve into its first position.

6. In a hydrauic system; a reciprocable plunger having a main area and a difierential area; a fluid source; a reversing valve movable to connect said source with both of said areas for rapid advance of said plunger, or with said main area for a feed stroke of said plunger, or with said dierential area for a retraction stroke of said plunger, fluid operable means for actuating said valve; a rotary pilot valve movable into a first position to supply both of said fluid operable means to move said 'eversing` valve to its first mentioned position or. into a second position or supplying one of said fluid operable means to move said reversing valve into its second mentioned position or, into a third position to supply the other of said fluid operable means for moving said reversing valve into its last mentioned position; a ratchet on said pilot valve; a pair of spaced pawls carried by said plunger and operable during the advancing movement thereof for engaging said ratchet and actuating said pilot valve into its second and third positions respectively; a third pawl also carried by said plunger and operable during the retraction stroke thereof for engaging said ratchet and actuating said pilot valve into its first position and means for making said third pawl selectively efiective or inefi'ective.

'7. In a hydraulic system; a fluid motor having advancing and retracting means; a' constant delivery pump for supplying said means; a reversing valve connecting said pump with said advancing and retracting means and movable to connect said pump with one or the other of said means; a poppet valve having one side connected with said pump and being movable to connect said pump with exhaust; a restricted passage connecting 'the other side of said valve with said one side, the said other side being larger than said one side OE' normally urging said valve closed in response to equal. pressures on both sides thereoi; a first valve manually operable for exhausting said other side to bypass the delivery of said pump; a second valve responsive to a predetermined discharge pressure of said pump for exhausting said other side to bypass at least a part of the delivery of said pump; a flow restricting means connected to receive the discharge from said retracting means and to develop a pressure therein proportional to the advancing speed of said motor; a third valve responsive to a predetermined pressure at the inlet of said flow restricting means for exhausting said other side to bypass at least a part of said pump delivery thereby to control the speed oi' said motor; and means responsive to the shifting of said reversing valve to direct the pump discharge to said retracting means for making said flow restricting means inefiective.

8. In a hydraulic system; a fluid motor having advancing and retracting means; a constant delivery pump; a reversing valve connecting said pump with said means; separate discharge passages for said advancing and retracting means extending from said reversing valve to exhaust; flow restricting means in the discharge passage for said retracting means between said reversing valve and exhaust; a bypass valve connected between said pump and exhaust; opposed fluid operabie means connected with the discharge side of said pump for normally maintaining said bypass valve closed and means for exhausting one of said fluid operable means to permit said bypass valve to open and comprising a manually operated valve, a pressure responsive valve connected to be actuated by the pump discharge pressure, and a second pressure responsive valve connected to be actuated by a predetermined pressure at the inlet of said flow restricting means.

WARREN R. TUCKER.

REFERENES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Twyman Dec. 23, 1941