US3779136A

US3779136A - Valve unit for controlling double acting fluid operating cylinders

Info

Publication number: US3779136A
Application number: US00243102A
Authority: US
Inventors: H Hohlein
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 1972-04-11
Filing date: 1972-04-11
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18

Abstract

A system comprising a fluid motor and a valve unit having a movable slide connecting in its end positions, one side of the fluid motor to a fluid source under pressure and the other side of the fluid motor to exhaust and connecting in its central position, both sides of the fluid motor to the fluid source under pressure. Solenoid valves actuate the movable slide so that, when de-energized, the slide is caused to move into its central position so that the fluid motor is immediately supplied with fluid under pressure on both sides of the slide and retained in every intermediate and end position.

Description

United States Patent [1 1 Hohlein Dec. 18, 1973 VALVEUNIT FOR CONTROLLING DOUBLE ACTING FLUID OPERATING [73] Assignee: Volkswagenwerk Akt.,Wolfsburg,

Germany [22] Filed: Apr. 11, 1972 [21] Appl. No.: 243,102

Related U.S. Application Data [62] Division of Serv No. 54,915, July 15, 1970.

{52] US. Cl 91/361,91/403, 91/446, 91/461 [51] Int. Cl. FlSb 13/16 [58] Field of Search 91/358 R, 358 A, 91/403, 410, 361

[56] References Cited UNITED STATES PATENTS 2,267,177 12/1941 Twyman 91/403 6/1944 Carlton 91/410 10/1969 Fry et a1. 91/410 Primary Examiner-Paul E. Maslousky Att0rney-Lawrence R. Radanovic ['5 7] ABSTRACT A-system comprising a fluid motor and a valve unit having a movable slide connecting in its endpositions, one side of the fluid motor to a fluid source under pressure and the other side of the fluid motor to ex haust and connecting in its central position, both sides of the fluid motor to the fluid source under pressure. Solenoid valves actuate the movable slide so that, when tie-energized, the slide is caused to move into its central position so that the fluid motor is immediately supplied with fluid under pressure on both sides of the slide and retained in every intermediate and end position.

2 Claims, 4 Drawing Figures PAIENTEU 0501 a ma SHEHIBFZ PATENTEDBEU W5 3,779.1 36

i FIG.3 gg g I55 VALVE UNIT FOR CONTROLLING DOUBLE ACTING FLUID OPERATING CYLINDERS This is a division, of application Ser. No. 54,915, filed July 15, 1970.

This invention relates to valves with a five-way threeposition slide for the control of double-acting operating cylinders with pneumatic or hydraulic drive, the pistons of which are capable of being stopped quickly upon operation of a proper protective device and capable of beingmaintained in this stop position.

Valves with five-way three-position slides have been used for the control of double-acting operating cylinders. The middle position of the slide is normally used to arrest the operating piston. In known structures, both sides of the piston are acted upon in this middle position with the full network or grid system of pressure whereby a satisfactory stopping and stability of a position cannot be achieved because the forces developing by outside weights and varying piston surfaces are not.

compensated for. In other designs, all channels of the valve are closed in the middle stopping position of the slide, such valve exhibiting a good stopping behavior even for substantially large masses because a unilateral increase in the braking pressure is made possible. The resiliency resulting from such design is, however, undesirable and, moreover, because of a one-sided dead load or because of varying piston surfaces with accompanying leaks in the lines or in the piston, it is impossible to maintain the stop position. The greatest drawback of such valve, however, is that, with continued travel after a prolonged stop position, the air necessary for the action of the exhaust air throttles and so that the damping effect escapes because of leaks thereby causing an unintended rapidity of movement.

A further disadvantage of known valves having fiveway, three-position slides is that, in the event of an emergency stop, the cylinders of an installation are no longer capable of receiving or absorbing outside forces and will possibly leave their end position which has 'already been reached.

It is therefore an object of the present invention to provide a valve which permits the adjustment of the pressures at the sides of the cylinder necessary to effect a stable stop position of the operating piston so as to correspond with the pertinent load and piston conditions in such a manner that the required equilibrium condition will be fulfilled and will be maintained even in the event of leakage. Besides, the piston must be capable of receiving outside forces in its end positions.

Further objects of the invention will become apparent from the following description of the invention k or sealed system. Neither of the two end positions which is 104 (position d) and 105 (position a) is operated.

For a downward movement in direction (b) slide 100 must assume the left-hand position, whereby channels P are connected with B and A is connected with R and hand end position of'slide 100, whereby there exists a when considered in conjunction with the accompanyplate 106 by a slide 100 movable within a slide housing 109 (constituting a five-way valve unit). In the middle position of 'the slide as shown, piston 102 is braked down and is maintained as in the case of a leak-proofconnection from P to A and from B to S with an adjust ment in speed through the exhaust air throttle 108. In the upward position of the piston, the end position switch 105 is operated. The two additional pre-control or servo-pistons, comprised of parts 111, 113, I15 and 117 for the left-hand side, and comprised of

parts

112, 1 14, 116 and 118 for the right-hand side, have been arranged on or in the ends of slide 110. As compared to the use of two springs in known slide designs, they serve to move slide 100 into the middle position by pressure on the

pre-control chambers

123 and 125, as well as on the

chambers

124 and 126. Pressure in

chambers

124 and 126 and relief of

chambers

123 and 125 brings about a left-hand slide position Y. Conversely, pressure on 123 and 125 and relief of

chambers

124 and 126 brings out of the right-hand slide position X. The dimensions of the control surfaces have been intentionally designed such that surfaces F(D are more than twice as large as surfaces fld), so that the force corresponding to the surfaces F(D) minus f(d) for movement of the slide into the middle position is larger than theforce bringing about the end positions and corresponding to the surfaces fld). With this measure, the assurance for reaching the middle position is considerably increased because a sluggishly moving slide or a slide having a tendency to stick would not reach the end position with a smaller force, but it is assumed that with the greater force the middle position for stopping the piston will still be safely achieved.

A further important characteristic of the slide arranged in such manner is that it maintains its end position achieved at any one time through friction of

packings

113, 115, 114 and 116 when all

control chambers

123, 125, '124 and 126 are without pressure. This characteristic is exploited for the stability of the end positions.

For a description of the function of the pre-control or pilot unit 164 and the

solenoid valves

154, 155, 156 and 157, reference is made to FIGS. 2 and 3. Of these valves, 154 and 155 detsignate a first pair, and 156 and 157 designate a second pair.

The pilot pressure comes from channel P through hand position into the channel l43, and from there via the not-operated pilot or shifting

valves

137 and 138, and via the channels or

supply passages

129 and 130 into the

pre-control chambers

123 and 125 or 124 and 126. As a'result, the middle position of the slide will be achieved and the operating piston 102 will be stopped. (

Channels

136 and 143 are designated as main fluid supply channel means). Furthermore, there is a pres sure below the

solenoid valves

154 and 155. All other channels are without pressure.

Now, if movement of the operating piston is to take place in the direction a, the solenoid valve 155 is energized by manual or operatic operation of a key 160, as a result of which pressure will reach solenoid valve 157 which at first is still locked or closed. The pressure reaches channel 148 as well as into channel 127 via throttle 140, which channel 127 is closed at its end by a middle position stop 117 acting simultaneously as a valve disc so that the pressure can build up on the control piston of pilot valve 138 which, as a result thereof, assumes a left-hand switching position. Thus, channel 130 and

control chambers

124 and 126 are relieved so that slide 110 and piston l 12 will be shifted to the right toward stop 120 by the pressure in chamber 125 appearing on the left, as a result of which the movement of piston 102 in direction a takes place. Disconnection of key or knob 160 again brings about the starting condition. Through short time manual operation, piston 102 can therefore be moved into any desired position slowly by way of short partial movements.

Now, if piston 102 has reached its lowermost position with an energized solenoid valve 155 and operates the pilot end position switch 105, and thus solenoid valve 157 is energized, channel 152, the right side of the bore member OR 150 obtains pressure or is placed under pressure, as a result of which channel 151 is closed. The large left-hand piston of storage valve 146 is acted upon through channel 149 and said valve is pushed to the right although pressure appears on the right-hand small piston surface by means of the OR member 144 and channel 145. In this position, channel 143, channel 129 and the left-hand pre-control

chambers

123 and 125 are relieved so that the end position X of the slide, and thus the pressure chamber A is maintained. After a drop in pressure has taken place, key 160 and plug 161 or the energized switch 162 or the main switch 163 may be disconnected, whereby

channels

148, 127, 145, 152 and 149 and thus both sides of storage valve 146, will be relieved through solenoid valve 155 and particularly also solenoid valve 157 without, however, the storage valve changing its position. The right-hand end position of slide 100 thus will be maintained. The subsequent switching back of'valve 138 will likewise be without any effect.

Piston 102, being under pressure in the end position A is therefore in a position now to absorb outside forces.

The movement of operating piston 102 into the opposite or left-hand direction is introduced by operation of key 159 and energization of solenoid valve 154. The pressure in channel 147 made possible by throttle 139 and the blocked non-returned valve 141, will first of all have an effect on the right-hand piston surface of storage valve l46 via the OR member 144 blocking channel 148 and via channel 145. Since the larger left-hand piston surface is without pressure, (

solenoid valves

155 and 156 are not energized) the piston of valve 146 again assumes the left-hand position and channel 143 obtains pressure or is placed under pressure which also reaches the right-hand pre-control

chambers

124 and 126 via the not-operated valve 138 and channel 130 (solenoid valves 154 to 157 are shown more clearly in FIG. 3). The left-hand pilot valve 137 will at first not yet be switched because channel 128 is still connected with the relief channel 122 in the pre-control chamber 124. Therefore,

chambers

123 and 125 also obtain pressure via pilot valve 137 and channel 129. The pistime. Only when channel 128 is closed by stop 118 acting as a valve packing and when the pressure is being built up, valve 137 is shifted to relieve channel 129 and

chambers

123 and 125, as a result of which slide moves to the left because of the pressure in chamber 126 and causes the movement of piston 102 in the direction B. The opening of the end position switch caused thereby and releasing of solenoid valve 157 in that case, remains without effect. Now, at every point of the stroke, a stop is possible again through opening of 159, 161, 162 or 163, and a short time actuation by way of key 159 is again possible. Only the end position switch 104 closing in the end position B again effects or brings about the right-hand position of storage valve 146 by means of solenoid valve 156 and the OR member 150, as a result of which slide 100 will maintain its position Y because of relief on both sides and the pressure prevailing in channel B also stabilizes piston 102 against outside forces in this end position with simultaneous relief of the piston side A. The countermovement can then be triggered again only by key 160, solenoid valve 155 via back-switching of storage valve 146, middle position of the slide, shifting of valve 138 and movement of slide 100 to the right. At first, this indeed seems to be a time-comsuming process. However, by correspondingly large dimensioning of

values

137, 138 and 146 as well as of

channels

131, 136, 143, 129 and 130, it is possible to maintain the time for this process within reasonable limits.

The requirement that a perfect functioning of all movable parts be a prerequisite for a normal operating function will be fulfilled regarding pilot pistons 11 1 and 112 necessary for the middle position by the abovedescribed method, in such a manner that a countermovement can take place from the end position of the piston only when the middle position has been reached previously satisfactorily for a short period of time. There, for example, valve 137 does not shift back, then slide position B cannot be left. If it does not switch, then position B will not be reached and the same is true for valve 138 with effects on position A. I

Whenever storage valve 146, after operating

solenoid valves

154 or 155, does not shift back'into the left-hand position, slide 100 can no longer change its position because the control pressure is missing and a piston movement is no longer possible. If it does not shift toward the right in the end position of the piston, then there follows the harmless or not dangerous middle position after discontinuance of the approach and in the case of an outside power effect on piston 102, the latter will leave its end position and thus its pilot end

position safety switch

104 or 105. This likewise leads to a harmless operational breakdown. If solenoid valve 154 does not shift back in the stabilized end position B of the cylinder, a shifting into the opposite position A is no longer possible because the large left side of storage valve 146 is still under pressure by means of 156, 151, 150 and 149, with the result that the storage valve 146 cannot be shifted back. This is likewise true for solenoid valve 155. 7

Whenever solenoid valve 156 or end position, switch 154 no longer shifts back, movement in direction a and the stabilization in the uppermost position is still possible whereby storage valve 146 has assumed its righthand position. In the case of the next actuation of key 159 and solenoid valve 154, however, storage valve 146 will receive pressure also on the large left-hand opcrating surface so that it cannot shift to the left and a movement of slide 100 is no longer possible. Logically, the same is true for solenoid valve 157 and end position switch 105. Thus, the valve on the basis of the enumerated characteristics may be called intrinsically safe.

In order to keep impurities away from the pilot or operating medium which can disturb the function of the storage valve 146 executed predominantly as a slide without sealing, an exchangeable filter 133 is provided.

By a turn of packing 135 throughout 180 degrees, it is possible moreover to feed in the pilot medium separately at connection 134 of plate 132 whenever main slide 100 is to be operated with a higher pressure.

In the case of use of the valve in a purely pneumatic or hydraulic system,

solenoid valve

154 and 155 may be omitted. The distribution then takes place directly to

channels

147 and 148.

Solenoid valves

156 and 157 must then be replaced by valves that can be controlled pneumatically or hydraulically and which are then operated by pilot end position valves. The function is otherwise the same.

Whenever

solenoid valves

154 and 155 fail to operate, no control takes place.

lf solenoid valve

156 or 157 fail to operate, the same harmless effect is present as already described as though storage valve 146 is obstructed in its movement toward the right.

Thus, the requirement has already been fulfilled, namely that the perfect functioning of all the movable parts is the prerequisite for the normal operation and that in the case of breakdowns, a piston stroke is no longer possible, nor does a stopping occur.

For a further smooth operation, the valve therefore has to be exchanged. Beyond that, perfect functioning of pilot end switches 104 and 105 will be checked by this valve during every operating cycle because a movement out from an end position can be effected only when the end position switch of the opposite end position is not operated. An electrical control, which in other instances is normally required, is not needed here.

Obviously, many modifications and variations of the invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim:

1. A system comprising, a fluid motor formed by a double-acting operating cylinder (101) having two pressure chambers on different sides ofa piston (102), a conduit connected to each of said pressure chambers, a five-way valve unit, said unit comprising: channel means (P) containing fluid under pressure; further channel means (R, 8) leading to exhaust means; a housing (109); a slide (100) having recesses therein and being disposed for sliding movement in said housing; said fluid motor and said channel means and said furthcr channel means being operatively interconnected via said conduits and said recesses in said'slide, said channel means and said further channel means opening into said housing respectively through said recesses; said housing at both ends of said slidedefining precontrol chambers (123 and 124), pre-control pistons (111, 113, 115, 117: 112, 114, 116, 118) being respectively located in said pre-control chambers (123 and 124) for sliding movement within said housing, equal pressure within said chambers effecting a normally centered position of said slide within said housing;

two pair of solenoid valves (154, 156; 155, 157) provided to selectively connect, when selectively energized, said precontrol chambers to one of said channel means and said further channel means, said slide moving into one of its end positions when one of said pre-control chambers is connected to said channel means and into the other of its end positions when the other of said pro-control chambers is connected to said channel means thereby selectively connecting one of saidpressure chambers of said fluid motor to said channel means and the other of said pressure chambers to said further channel means, a first pair (154, 155) of said valves being energized by switches (159, 160), main fluid supply channel means (136, 143) containing fluid under pressure and being interconnected with said pre-control chambers through supply passages (129, 130), said first pair of valves being connected to said main channel means, the second pair (156, 157 of said valves being energized by end-position switches (104, actuated by said first pair of valves;

a storage valve (146) provided in said main channel means (136, 143) downstream of the connection between said main channel means (136, 143) and said solenoid valves, said storage valve being interconnected with said first and second pair of said valves and being shiftable into its valve opened position when one of said first pair of said solenoid valves (154, 155) is energized to open said main channel means (136, 143) and into its valve closed position when one of said second pair of said solenoid valves (156, 157) is energized to shut off said main channel means (136, 143) to thereby connect said supply passages (129, downstream of said storage valve (146) leading to said pre-control chambers, and;

two shifting valves (137, 138) respectively provided in said supply passages (129,, 130), each of said shifting valves being spring-biased into their valve opened position to open said supply passages (129, 130), and each of said shifting valves being connected to one of said first pair of said solenoid valves (154, and being shiftable by energizing said first pair of said solenoid valves (154, 155) into a valve'closed position to shut off said supply passages (129, 130) and to connect one of said pre control chambers to said further channel means. 2. A system according to claim 1, wherein said storage valve (146) is a piston valve having two pistons interconnected by a rod, said pistons. having different op erating surfaces, the greater surface of which is connected to said second pair of said solenoid valves (156, 157) and the smaller surface of which is connected to said 'first pair of said solenoid valves (154, 155).

1 UNITED STATES PATENT OFFICE 1 CERTIFICATE OF CORRECTION 1 Patent No. 3,779,136 Dated December 18, 1973 Inv t fl Herman Hohle in It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: 1

in the title page please insert --Claims priority on i Qermany "No. P 19 36 370.3, filedifuly 14,

Signed and sealec l this 30th day of July 19 74.

(SEAL) Attest:

MCCOY M. GIBSONyJR'. c. MARSHALL DANN Attesting Officer Commissioner of Patents

Claims

1. A system comprising, a fluid motor formed by a double-acting operating cylinder (101) having two pressure chambers on different sides of a piston (102), a conduit connected to each of said pressure chambers, a five-way valve unit, said unit comprising: channel means (P) containing fluid under pressure; further channel means (R, S) leading to exhaust means; a housing (109); a slide (100) having recesses therein and being disposed for sliding movement in said housing; said fluid motor and said channel means and said further channel means being operatively interconnected via said conduits and said recesses in said slide, said channel means and said further channel means opening into said housing respectively through said recesses; said housing at both ends of said slide defining pre-control chambers (123 and 124), pre-control pistons (111, 113, 115, 117: 112, 114, 116, 118) being respectively located in said pre-control chambers (123 and 124) for sliding movement within said housing, equal pressure within said chambers effecting a normally centered position of said slide within said housing; two pair of solenoid valves (154, 156; 155, 157) provided to selectively connect, when selectively energized, said precontrol chambers to one of said channel means and said further channel means, said slide moving into one of its end positions when one of said pre-control chambers is connected to said channel means and into the other of its end positions when the other of said pre-control chambers is connected to said channel means thereby selectively connecting one of said pressure chambers of said fluid motor to said channel means and the other of said pressure chambers to said further channel means, a first pair (154, 155) of said valves being energized by switches (159, 160), main fluid supply channel means (136, 143) containing fluid under pressure and being interconnected with said pre-control chambers through supply passages (129, 130), said first pair of valves being connected to said main channel means, the second pair (156, 157) of said valves being energized by end-position switches (104, 105) actuated by said first pair of valves; a storage valve (146) provided in said main channel means (136, 143) downstream of the connection between said main channel means (136, 143) and said solenoid valves, said storage valve being interconnected with said first and second pair of said valves and being shiftable into its valve opened position when One of said first pair of said solenoid valves (154, 155) is energized to open said main channel means (136, 143) and into its valve closed position when one of said second pair of said solenoid valves (156, 157) is energized to shut off said main channel means (136, 143) to thereby connect said supply passages (129, 130) downstream of said storage valve (146) leading to said pre-control chambers, and; two shifting valves (137, 138) respectively provided in said supply passages (129, 130), each of said shifting valves being spring-biased into their valve opened position to open said supply passages (129, 130), and each of said shifting valves being connected to one of said first pair of said solenoid valves (154, 155) and being shiftable by energizing said first pair of said solenoid valves (154, 155) into a valve closed position to shut off said supply passages (129, 130) and to connect one of said pre-control chambers to said further channel means.

2. A system according to claim 1, wherein said storage valve (146) is a piston valve having two pistons interconnected by a rod, said pistons having different operating surfaces, the greater surface of which is connected to said second pair of said solenoid valves (156, 157) and the smaller surface of which is connected to said first pair of said solenoid valves (154, 155).