US3906838A

US3906838A - Control apparatus for hydraulically operated consumers

Info

Publication number: US3906838A
Application number: US367012A
Authority: US
Inventors: Friedrich-Wilhelm Hofer
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1972-07-05
Filing date: 1973-06-04
Publication date: 1975-09-23
Anticipated expiration: 1992-09-23
Also published as: DE2232857C2; FR2191041B1; SE381921B; DE2232857A1; IT990927B; FR2191041A1; GB1387367A; BR7304958D0; BE801922A; CH553926A; AT322249B; JPS4944177A

Abstract

Apparatus which controls the flow of pressurized hydraulic fluid from a pump to a primary consumer or to a secondary consumer and from the primary consumer to the tank has a distributor valve whose spool changes its position in response to changes of fluid pressure in a control chamber wherein the fluid pressure is controlled by a pilot valve which can be actuated manually, electrically or by means of a fluid. A check valve which is interposed between the distributor valve and the primary consumer controls the speed of movement of the spool of the distributor valve to that position in which the primary consumer receives fluid. The secondary consumer receives fluid whenever the primary consumer is sealed from the pump. A further pilot-controlled valve is provided to control the flow of fluid from the primary consumer to the tank.

Description

1451 Sept. 23, 1975 CONTROL APPARATUS FOR HYDRAULICALLY OPERATED CONSUMERS Friedrich-Wilhelm Hiifer, Hofingen, Germany [73] Assignee: Robert Bosch G.m.b.H., Stuttgart,

Germany [22] Filed: June 4, 1973 [21] Appl. No.: 367,012

[75] Inventor:

[30] Foreign Application Priority Data July 5, 1972 Germany 2232857 [52] US. Cl. 91/413; 91/459; 91/461 [51] Int. Cl. F15B 11/16 [58] Field of Search 91/412, 461,413, 304, 91/459, 275, 361; 60/422, 427, 484; 251/43,

[56] References Cited UNITED STATES PATENTS 822,306 6/1906 Sanger 251/42 3,437,102 4/1969 Hamilton 91/461 X 3,465,519 9/1969 McAlvay et al. 60/422 3,646,851 3/1972 Mohri.... 91/461 X 3,654,837 4 1972 Knapp 91/461 3,662,548 5/1972 Suzuki et a1. 91/412 X 3,789,739 2/1974 Krehbiel et alv 91/461 OTHER PUBLICATIONS U.S. ReRe-26, 523, F. H. Tennis, Feb. 11, 1969.

Primary Examiner-Irwin C, Cohen Assistant Examiner Edward Look Attorney, Agent, or FirmMichael S. Striker [5 7] ABSTRACT Apparatus which controls the: flow of pressurized hydraulic fluid from a pump to a. primary consumer or to a secondary consumer and from the primary consumer to the tank has a distributor valve whose spool changes its position in response to changes of fluid pressure in a control chamber wherein the fluid pressure is controlled by a pilot valve which can be actuated manually, electrically or by means of a fluid. A check valve which is interposed between the distribu tor valve and the primary consumer controls the speed of movement of the spool of the distributor valve to that position in which the primary consumer receives fluid. The secondary consumer receives fluid when ever the primary consumer is sealed from the pump. A further pilot-controlled valve is provided to control the flow of fluid from the primary consumer to the tank.

14 Claims, 3 Drawing Figures SOLENOIDS FLUID CONSUMER US Patent Sept. 23,1975 Sheet 1 of 3 3,906,838

F l g .1

W SEC SOLENOIDS FLUID CONSUMER US Patent Sept. 23,1975 Sheet 2 of3 3,906,838

FLUID CONSUMER US Patent Sept. 23,1975 Sheet 3 01 3 3,906,838

49" SOURCE OF PRESSURE FLUID FLUID CONSUMER CONTROL APPARATUS FOR HYDRAULICALLY OPERATED CONSUMERS BACKGROUND OF THE INVENTION The present invention relates to control apparatus for hydraulically operated consumers, and more particularly to improvements in control apparatus for plural consumers of pressurized hydraulic fluid. Still more particularly, the invention relates to improvements in control apparatus which may be utilized to regulate the flow of fluid to and/or from one or more consumers which are mounted on or pulled by an automotive vehicle, especially a tractor or a similar towing vehicle for agricultural implements.

German Offcnlegungsschrift No. 2,034,214 discloses a control apparatus wherein a consumer can receive pressurized hydraulic fluid by way of a pilot-operated distributor valve and a check valve. The valve member of the distributor valve is movable relative to its housing in response to admission of pressurized fluid into or in response to evacuation of pressurized fluid from a control chamber at one axial end of the valve member. The control chamber can be connected with the tank by way of a flow restrictor which is adjustable so that the rate of fluid flow from the control chamber decreases in response to movement of the valve member toward one of its end positions. The pilot valve for the distributor valve is actuatable by mechanical means and the valve member of the distributor valve can assume three different positions including a neutral position in which pressurized fluid flows from the pump back to the tank, a second position in which the pressurized fluid is free to flow from the pump to a consumer, and a third position in which the fluid can flow from the consumer to the tank. In order to prevent the flow of fluid to the consumer at a maximum rate in immediate response to movement of the valve member to its second position, the control apparatus comprises a special switchover device which connects the aforementioned control chamber with the tank in such a way that the resistance to flow of fluid from the control chamber into the tank increases while the valve member approaches its second position. The switchover device is controlled by fluid pressure at the inlet and outlet of the control apparatus. The result is that the rate of flow of pressurized fluid to the consumer increases gradually in order to avoid undesirable pressure peaks.

A drawback of the just described control apparatus is that it comprises a substantial number of complex and expensive parts and that it is not sufficiently versatile to serve as a means for regulating the flow of pressurized fluid to or from several consumers. Also, the pressurized fluid which is circulated in the neutral position and/or third position of the valve member is wasted.

SUMMARY OF THE INVENTION An object of the invention is to provide a novel and improved apparatus for controlling the flow of pressurized fluid to several discrete consumers.

Another object of the invention is to provide a control apparatus wherein the fluid which is being pressurized by a pump or the like is used with greater economy and with less leakage than in heretofore known apparatus.

A further object of the invention is to provide a control apparatus which can be designed for preferential flow of fluid to a selected one of several consumers of pressurized hydraulic fluid.

An additional object of the invention is to provide the control apparatus with novel means for regulating the speed of movement of one or more parts (such as valve members) which determine the rate of fluid flow to or from one or more consumers.

An ancillary object of the invention is to provide a control apparatus wherein the aforementioned speed regulating action is largely independent from the rate of fluid flow and/or from the pressure of fluid.

The invention is embodied in an apparatus for controlling the flow of pressurized hydraulic fluid to first and second consumers, particularly to consumers (such as hydraulic cylinder and piston units, jacks, motors, valves or the like) mounted on or towed by an agricultural vehicle (e.g., a tractor). The apparatus comprises a pump or an analogous source: of pressurized hydraulic fluid, means defining an inlet connected with the pump and first and second outlets respectively connected with the first and second consumers, a reservoir which collects spent fluid and provides a supply for the pump, and a distributor valve interposed between the inlet and the two outlets and having a reciprocable spool or an analogous valve member movable between a plurality of positions including a predetermined position in which pressurized fluid is free: to flow toward the first outlet. The valve member is further arranged to establish a path for the flow of fluid from the inlet to the second outlet in at least some of its positions, and the apparatus further comprises regulating means for initiating the movements of the valve member and for controlling the speed of movement of the valve member toward the predetermined position. The regulating means includes means defining a control chamber, pilot valve means which is actuatable to connect the control chamber with the reservoir or with the pump to thereby respectively effect the movement of the valve member to and from the predetermined position, and check valve means interposed between the distributor valve and the first outlet and having means for reducing the rate of fluid flow from the control chamber to the reservoir during opening of the check valve means and while the pilot valve means connects the control chamber with the reservoir.

The fluid pressure in the control chamber preferably equals the fluid pressure at the second outlet in the other positions of the valve member, i.e., when the valve member permits pressurized fluid to flow from the inlet to the second outlet.

The regulating means is preferably provided with bore means which connects the pilot valve means with the control chamber, and the means for reducing the rate of fluid flow from the control chamber may comprise a second valve member which forms part of the check valve means and is movable from a sealing position (in which the inlet is sealed rom the first outlet) toward an open position to thereby interrupt or at least substantially reduce the flow of fluid from the control chamber by way of the bore means. The arrangement may be such that, when the second valve means seals the bore means, the fluid can still flow from the control chamber to the reservoir by way of a fixed flow restrictor.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved control apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partly diagrammatic sectional view of a control apparatus for the flow of fluid to two hydraulically operated consumers which embodies one form of the invention and which employs two solenoidoperated pilot valves;

FIG. 2 is a similar view of a second control apparatus which employs two mechanically operated pilot valves; and

FIG. 3 is a similar view of a third control apparatus which employs two fluid-operated pilot valves.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, there is shown a control apparatus having a housing or body which comprises two units or sections, namely a main unit or section 1 and a pilot unit or section 2. The main section 1 is provided with an inlet or pressure channel 3 which is connected with a supply conduit 5 for admission of pressurized hydraulic fluid from a suitable source, such as a pump 4. The pump 4 draws fluid from a reservoir or tank 6. A branch line 7 which communicates with the inlet 3 contains a safety valve here shown as a pressure relief valve 9. When the valve 9 is open, the branch line 7 communicates with a return conduit 8 which discharges fluid into the tank 6.

The main housing section 1 is further provided with an elongated bore 11 for the valve member or spool 13 ofa distributor valve 12. The purpose of the distributor valve 12 is to switch over from admission of pressurized fluid to a first or primary consumer 35 to admission of pressurized fluid to a second or auxiliary consumer 20, or vice versa. The bore 11 for the spool 13 communicates with several grooves which are machined into the main section 1. These grooves include a first annular groove which communicates with the inlet 3. In the illustrated axial position of the spool 13, the groove 10 communicates with a second annular groove 18 which admits pressurized fluid to a channel 19 constituting an outlet for admission of pressurized fluid to the auxiliary consumer 20. A land or piston 17 of the spool 13 is shown as being located intermediate the two axial ends of the groove 10 so that the fluid can flow from the inlet 3 to the outlet 19. The piston 17 is bounded by two concentric grooves and 16 machined into the peripheral surface of the spool 13. The latter is permanently biased in a direction to the right, as viewed in FIG. 1, by a helical spring 14 which is installed in the left-hand end portion of the bore 11. The auxiliary consumer 20 is assumed to constitute a distributor valvewhich can admit pressurized fluid to the motor of a harvester or to the motor of a winch, not shown.

The main housing section 1 is further provided with a third annular groove 21 which is located to the left of the groove 10 and communicates with the axial bore 11. The groove 21 can admit pressurized fluid to a channel 22. The piston 17 of the spool 13 is provided with one or more axially parallel notches 17 whose depth increases in a direction from the groove l5 toward the groove 16 and which serve for accurate regulation of the flow of fluid from the inlet 3 to the outlet 19. That end portion of the bore 11 which receives the helical spring 14 communicates with the return conduit 8 by way ofa channel 8a so that the pressure in this end portion of the bore 11 equals atmospheric pressure.

A further annular groove 24a in the housing of the main unit 1 forms part of a control chamber 23 which is adjacent to the right-hand axial end of the spool 13. The rightmost portion 24 of the control chamber 23 constitutes a cylinder chamber which can receive the adjacent right-hand end portion of the spool 13 when the spring 14 is free to expand. The right-hand end portion of the spool 13 is provided with one or more flowrestricting notches 25 which control the rate of fluid flow from the cylinder chamber 24 into the groove 24a while the spool 13 moves under the action of the spring 14.

The pilot section 2 of the housing is sealingly connected with the main section 1 and is formed with a channel or bore 29 which extends into the main section 1 and communicates with the groove 24a. That portion of the channel or bore 29 which is provided in the main section 1 contains a fixed flow restrictor 30 offering a predetermined resistance to the flow of fluid therethrough. The righthand end of the channel 29 communicates with an enlarged portion of a bore provided in the pilot section 2 for a pressure relieved 3-position 2-way pilot valve 27. This pilot valve comprises a valve member 27a, a solenoid 26 which can be energized to move the valve member 27a downwardly, as viewed in FIG. 1, and a helical spring 27b which biases the valve member 27a upwardly. The lowermost part of the bore for the valve member 27a of the pilot valve 27 communicates with a return line or channel 31 which is machined in part into the pilot section 2 and in part into the main section 1 and communicates with a discharge opening 31a connected to the return conduit 8 so that the fluid issuing from the opening 31a can return into the tank 6. In the illustrated axial position of the valve member 27a (solenoid 26 deenergized), the pilot valve 27 connects the channel or bore 29 with a branch line 28 which communicates with the inlet 3. Thus, when the spring 27b is free to expand, the pilot valve 27 allows fluid to flow from the pump 4 into the control chamber 23 by way of the supply conduit 5, inlet 3, branch line 28, the bore for the valve member 27a, channel or bore 29 and fixed flow restrictor 30.

The aforementioned channel 22 communicates with a blind bore 39 which is machined into the main section 1 and receives a check valve or one-way valve 32 serving to directly control the admission of pressurized fluid t0 the primary consumer 35. When the check valve 32 is open, pressurized fluid can flow from the channel 22 into an outlet 33, which is machined into the main section 1, and thence to the primary consumer 35 by way of a working line 34. The primary consumer 35 comprises a cylinder 35a, a piston 35b and a piston rod 35c. The piston rod 35c is assumed to be connected to the table of a harvester forming part of a harvester thresher (not shown) so that the table rises when the chamber 35d of the cylinder 35a receives pressurized fluid.

The check valve 32 comprises a conical valve member 36 which is biased against a seat in the main section 1 by a helical spring 38. The valve member 36 has an extension or plunger 37 which is reciprocable in the blind bore 39 and is provided with a circumferential groove 40. When the extension 37 assumes the axial position shown in FIG. 1, i.e., when the check valve 32 is closed, the pressurized fluid which flows in the channel or bore 29 can bypass the flow restrictor 30 by flowing through a bore 41, through the groove 40, and thereupon through a further bore 42 which discharges into the channel 29 downstream of the flow restrictor 30. It will be seen that the extension 37 constitutes a means for changing the rate of fluid flow to or from the control chamber in response to movement of the valve member 36 in the bore 39.

The main section 1 further receives a fluiddischarging valve 44 which can be actuated to allow hydraulic fluid to flow from the chamber 35a of the cylinder 35a of the primary consumer 35 back into the tank 6. The valve member 45 of the discharging valve 44 has a conical portion 59 which normally bears against a seat in the main section 1 under the action of a helical spring 52. The conical portion 59 of the valve member 45 then seals the discharge opening 31a from a channel 43, and thus from the outlet 33, as long as the valve 44 remains closed. The valve member 45 has an axially extending flow restricting bore 46 which can communicate with the return line 31 in response to opening of a second pressure relieved pilot valve or shutoff valve 49 provided in the pilot section 2. The pilot valve 49 comprises a valve member 49a which normally engages a seat under the action of a spring 49b and can be displaced against the opposition of the spring 49b in response to energization of a solenoid 48. When the solenoid 48 is energized, the valve member 49a moves upwardly and thereby connects a pilot line 47 with the return line 31. The valve member 45 is reciprocable in a bore 50 provided in the main section 1. The right-hand portion of the bore 50 constitutes a chamber which is filled with fluid and accommodates the aforementioned spring 52 and receives hydraulic fluid by way of a flow restricting orifice 51 provided in a valve plate 53 which is biased against an internal shoulder or seat of the valve member 45 by the spring 52. The valve plate 53 is received in a bore 54 of the valve member 45. The orifice 51 allows fluid to escape from the right-hand end portion or chamber of the bore 50 when the valve member 45 is caused to move in a direction to the right, as viewed in FIG. 1.

The means for actuating the

pilot valves

27 and 49 of the pilot unit 2 comprises a selector switch 55 having a handle 56. The median contact 55c of the switch 55 is connected with an energy source 155 and can be moved into engagement with a second contact 55a to thereby energize the solenoid 26 or into engagement with a third contact 55b to thereby complete the circuit of the solenoid 48. The handle 56 is accessible to the operator of the control apparatus, for example to the driver of an agricultural tractor.

The operation is as follows:

When the handle 56 of the selector switch 55 is maintained in its central or neutral position, the median contact SSC is disengaged from the

contacts

55a and 55b so that the

solenoids

26 and 48 are deenergized. Such position of the handle 56 corresponds to the neutral condition or setting of the control apparatus. The pressurized fluid which is being furnished by the pump 4 flows from the supply conduit 5 into the inlet 3 of the main section 1. The piston 17 of the spool 13 is located between the grooves and 21 so that it seals the inlet 3 from the channel 22 and outlet 33. The fluid can flow into the outlet 19 and to the secondary consumer 20. The check valve 32 is closed so that it prevents the flow of fluid between the channel 22 and the outlet 33.

The fluid also flows from the inlet 3 into the branch line 28 and into the bore for the valve member 27a of the pilot valve 27. The valve member 27a allows such fluid to flow into the channel 29 and control chamber 23 by way of the flow restrictor 30. At the same time, the fluid can reach the control chamber 23 by way of the

bores

41, 42 and groove 40 in the extension 37 of the valve member 36. The fluid pressure in the control chamber 23 suffices to maintain the spool 13 in the lefthand end position in which the helical spring 14 stores energy and the piston 17 seals the inlet 3 from the channel 22. The secondary consumer 20 can admit pressurized fluid to one or more motors or other fluid consuming devices, or returns the fluid into the tank 6. As mentioned before, the secondary consumer 20 may constitute a distributor valve which can admit pressurized fluid to the motor of the harvester and/or to the motor of a winch. The pressure of fluid in the control chamber 23 equals the pressure at the outlet 19 when the pump 4 supplies pressurized fluid to the consumer 20.

If the operator thereupon decides to raise the aforementioned table, i.e., to admit pressurized fluid to the chamber 35d of the cylinder 35a of the primary consumer 35, the handle 56 of the selector switch 55 is pivoted in a clockwise direction, as viewed in FIG. 1, so that the median contact 55c engages the right-hand contact 55a and thereby energizes the solenoid 26. The solenoid 26 displaces the valve member 27a against the opposition of the spring 27b so that the pilot valve 27 connects the channel or bore 29 with the return line 31 and simultaneously seals the branch line 28 from the channel or bore 29. Therefore, pressurized fluid can flow from the control chamber 23 to the tank 6 and the spring 14 is free to expand so as to shift the spool in a direction to the right, i..e., toward the cylinder chamber 24. The spool 13 then gradually reduces the rate of fluid flow from the inlet 3 to the outlet 19 so that the secondary consumer 20 is ultimately shut off from the pump 4. At the same time, the inlet 3 begins to communicate with the groove 21 and channel 22 to thereby increase the fluid pressure in the blind bore 39. When the pressure in the bore 39 exceeds the pressure in the outlet 33 and the bias of the spring 38, the valve member 36 moves in a direction to the left, as viewed in FIG. I, and allows the fluid to flow from the channel 22 to the outlet 33 and into the working line 34 and chamber 35d of the primary consumer 35. The extension 37 then shifts the groove 40 in a direction to the leftso that the bore 41 is sealed from the bore 42 and the fluid can flow from the control chamber 23 only by way of the fixed flow restrictor 30 in the channel or bore 29. This results in a substantial deceleration of axial movement of the spool 13 under the action of the helical spring 14, i.e., in substantial deceleration of the spool 13 during movement to a predetermined position in which the pump 4 supplies pressurized fluid to the outlet 33. Such deceleration of the valve member 13 takes place when the piston 17 travels along the housing portion separating the

grooves

10 and 18 whereby the notch or notches l7',insulre gradual reduction of fluid flow from the inlet 3 into the outlet 19. A further deceleration of the spool 13 against the action of the expanding spring 14 takes place when the right-hand end portion of the spool reaches the cylinder chamber 24. As mentioned before, the outflow of fluid from the chamber 24 into the groove 24a can take place only by way of the flow restricting notch or notches 25 which thereby insure that the movement of the spool 13 into the chamber 24 is gradual.

In the meantime, the valve member 36 is completely lifted off its seat in the main section 1 so that the valve 32 allows practically unobstructed flow of pressurized fluid from the channel 22 to the working line 34 and chamber 35d. It will be noted that the primary con sumer 35 has preference over the secondary consumer 20, i.e., that the consumer is shut off from the pump 4 when the consumer 35 receives pressurized fluid.

When the piston rod 350 of the primary consumer 35 has lifted the aforementioned table or another load to a desired level, the operator moves the handle 56 of the selector switch 55 back to the neutral position in which the median contact 550 is disengaged from the contact 55a. The solenoid 26 is deenergized and the valve member 27a of the pilot valve 27 is free to return to the illustrated position under the action of the spring 27b. The pressurized fluid is again free to flow into the control chamber 23 by way of the branch line 28 and chann'el or bore 29. Therefore, the spool 13 begins to move against the opposition of the spring 14. The pressure in the channel 22 decreases so that the check valve 32 closes under the action of the spring 38 and prevents further flow of pressurized fluid to the chamber 35d of the primary consumer 35. At the same time, the fluid in the chamber 35d is entrapped so that the table which is supported by the piston rod 35c cannot descend. The spool 13 then assumes an axial position in which the inlet 3 communicates with the outlet 19 so that the secondary consumer 20 can receive pressurized fluid.

If the operator thereupon desires to lower the load which is supported by the piston rod 350 of the primary consumer 35, the handle 56 of the selector switch 55 is moved to the position shown in FIG. 1 so that the solenoid 48 of the second pilot valve 49 is energized and moves the valve member 49a against the opposition of the spring 49b. The cylinder chamber 35d then communicates with the tank 6 by way of the working line 34, outlet 33, flow restricting bore 46 of the valve member 45, pilot line 47, return line 31 and discharge opening 31a. The orifice 46 acts as a flow restrictor so that the fluid pressure in the outlet 33 exceeds the fluid pressure in the pilot line 47 whereby the valve member 45 moves against the opposition of the spring 52 and connects the outlet 33 directly with the discharge opening 31a. However, the rate at which the fluid can flow from the outlet 33 and directly into the discharge opening 31a increases only gradually because the piston 45 can penetrate into the bore 50 only to the extent which is determined by the cross-sectional area of the orifice 51 in the valve plate 53. This orifice 51 prevents an abrupt descent of the load which is supported by the piston rod 350 of the primary consumer 35. The downward movement of the load which is supported by the piston rod 350 is interrupted as soon as the operator returns the handle 56 of the selector switch 55 to its neutral position. This deenergizes the solenoid 48 so that the pilot valve 49 closes to thus seal the pilot line 47 from the return line 31. Consequently, the pressure in the valve member 45 rises to match the pressure in the outlet 33 so that the spring 52 expands and returns the conical surface 59 of the valve member 45 into sealing engagement with its seat in the main section 1. When the pilot valve 49 closes in response to return movement of the handle 56 to its neutral position, the fluid which continues to flow from the outlet 33 via bore 46 moves the valve plate 53 away from the shoulder or seat at the left-hand end of the bore 54 so that the right-hand end of the bore 50 can communicate with the interior of the left-hand portion of the valve member 45 not only by way of the orifice or orifices 51 but also by way of the space surrounding the lifted-off valve plate 53 which insures a practically instantaneous return movement of the conical surface 59 into engagement with its seat.

The secondary consumer 20 receives pressurized fluid by way of the supply conduit 5, inlet 3,

grooves

10, 16 and outlet 19 in the neutral as well as in the lefthand end positions of the handle 56.

The control chamber 23, pilot valve 27 and the check valve 32 together constitute a regulating means which initiates the movements of the valve member 13 and which also controls the speed of movement of the valve member 13 toward its predetermined position in which the distributor valve 12 and the check valve 32 cooperate to admit pressurized fluid to the outlet 33. As mentioned before, the extension 37 of the valve member 36 reduces the rate of fluid flow from the control chamber 23 to the reservoir 6 during opening of the check valve 32 by moving the groove 40 out of register with the

bores

41, 42 while the pilot valve 27 connects the control chamber 23 with the reservoir 6.

An important advantage of the improved control apparatus is that the operator can rapidly shift from delivery of pressurized fluid to a selected one of several discrete consumers, that the delivery of fluid can be shifted from delivery to outlet 19 to delivery to outlet 33 with little loss in time but with a gradual decrease of fluid flow to the outlet 19, and that the braking of the valve member 13 is then determined by the fluid flowing to the outlet 33 for the primary or preferred consumer 35.

The control apparatus of FIG. 2 is similar to that of FIG. 1 and, therefore, all such parts which are identical with or clearly analogous to the corresponding parts of the first apparatus are denoted by similar reference characters. The main difference is that the pilot valves 27 and 49' do not employ solenoids; instead, the pilot section 62 of the housing supports a rotary shaft 64 for a wiper 63 which can displace an inner end portion or follower 27A of the valve member 27a or an inner end portion or follower 49A of the valve member 49a. The shaft 64 can be provided with a handle corresponding to the handle 56 of FIG. 1 or can be moved clockwise or counterclockwise by remote control. If the shaft 64 is connected with a handle, the latter is preferably movable relative to a scale having graduations or other symbols which indicate the momentary angular position of the shaft 64 and wiper 63. FIG. 2 shows the wiper 63 in its neutral position, i.e., the pilot valve 49' is closed and the pilot valve 27 allows the branch line 28 to communicate with the channel or bore 29. The chamber 35d receives pressurized fluid when the wiper 63 depresses the follower 27A, and the piston rod 350 can penetrate into the cylinder 35a under the weight of the load (table) thereon when the wiper 63 depresses the follower 49A.

In all other respects the operation of the control apparatus of FIG. 2 is identical with that of the first control apparatus.

The control apparatus of FIG. 3 is also similar to the apparatus of FIG. 1. The main difference is that the se lcctor means for actuating the pilot valve 27" or 49" in the pilot section 72 of the housing comprises a hydraulic or pneumatic selector device. As shown, the

valve member 49a of the pilot valve 49 will move to its open position in response to admission of pressurized fluid by way of a pipe 75, and the valve member 27a" of the pilot valve 27" will seal the branch line 28 from the channel or bore 29 in response to admission of pressurized fluid by way of a pipe 76. The admission of pressurized fluid from a source 77 to the

pipe

75 or 76 is regulated by a valve 78 which can connect the pipe 75 with the source 77 when the pipe 76 is connected to the tank 6, or vice versa. The valve 78 can further assume a neutral position in which the tank 6 is connected with the

pipes

75 and 76. The fluid which is admitted from the source 77 via pipe 75 can act against the underside of a piston 73 on the valve mem' ber 49a, and the fluid which is admitted from the source 77 via pipe 76 can act against the upper side of a piston 74 forming part of the valve member 27a".

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent:

1. Apparatus for controlling the flow of pressurized hydraulic fluid to fluid consumer motors, particularly to consumer motors mounted on or towed by an agricultural vehicle, comprising first and second consumer motors; a source of pressurized fluid; a housing including means defining an inlet connected to said source and first and second outlets respectively connected with said first and second fluid consumer motors; a reservoir; a distributor valve interposed between said inlet and said outlets and having a valve member movable between a plurality of positions including a predetermined position in which pressurized fluid is free to flow from said inlet towards said first outlet, said valve member being arranged to establish a path for the flow of fluid from said inlet to said second outlet in at least some other positions thereof; and regulating means for initiating the movements of said valve member and for controlling the speed of movement of said valve member toward said predetermined position, said regulating means comprising a control chamber, a pilot valve means actuatable to connect said chamber with said reservoir or with said source to thereby respectively effect a movement of said valve member to and from said predetermined position, and check valve means inter posed between said distributor valve and said first outlet and movable between a closed position in which it prevents flow of pressurized fluid from said distributor valve to said first outlet and an open position in which it permits flow of pressurized fluid from said distributor valve to said first outlet, said check valve means being biased to said closed position thereof and moved by prcssurizedfluid from said closed to said open position thereof when said valve member of said distributor valveiS in said predetermined position in which pressurized fluid is free to flow from said inlet through said distributor valve towards said first outlet; and flow reducing means for reducing the rate of fluid flow from said control chamber to said reservoir while said pilot valve means is actuated to connect said control chamber with said reservoir, said flow reducing means being movable between an inoperative position in which it does not affect the flow of fluid from said control chamber to said reservoir and an operative position in which it reduces the rate of flow of fluid from said control chamber to said reservoir, said flow reducing means being connected to said check valve means in such a manner so as to be moved into operative position when said check valve means is in open position and to be moved into inoperative position when said check valve means is in closed position.

2. Apparatus as defined in claim 1, wherein said valve member comprises means for gradually reducing the rate of fluid flow from said inlet to said second outlet during movement of said valve member toward said predetermined position.

3. Apparatus as defined in claim 2, wherein said means for gradually reducing the rate of fluid flow to said second outlet comprises: a piston having at least one peripheral notch.

4. Apparatus as defined in claim 1, wherein said chamber comprises a normally fluid-filled portion into which a portion of said valve member penetrates to expel the fluid therefrom during the last stage of movement of said valve member to said predetermined position.

5. Apparatus as defined in claim 4, wherein said portion of said valve member comprises flow restricting means for regulating the rate of fluid flow from said portion of said chamber during said last stage of movement of said valve member to said predetermined position.

6. Apparatus as defined in claim 1, wherein said pilot valve means comprises a pressure-relieved three-way two-position valve.

7. Apparatus as defined in claim 1, further comprising a passage connecting said first consumer with said reservoir, normally closed fluid discharging valve means in said passage, and second pilot valve means actuatable to open said fluid discharging valve means in one of said other positions of said valve member to thereby allow the fluid to flow from said first consumer to said reservoir.

8. Apparatus as defined in claim 7, wherein said fluid discharging valve means has a second valve member normally assuming a closed position and having a bore one end of which communicates with said first outlet and another end of which communicates with said reservoir in response to actuation of said second pilot valve means whereby the pressure differential between said ends of said bore suffices to effect the movement of said second valve member from said closed position.

9. Apparatus as defined in claim 8, wherein said fluid discharging valve means comprises a housing having a fluid-filled second bore for said second valve member, said second valve member having a passage connecting said first mentioned bore with said second bore and said fluid discharging valve means further comprising an apertured valve plate provided iii said second valve member to regulate the flow of fluid into and from said second bore and means for biasing said valve plate against a seat provided therefor in said second valve member.

10. Apparatus as defined in claim 7, wherein said second pilot valve means comprises a pressure-relieved shut-off valve.

11. Apparatus as defined in claim 7, further comprising electric actuating means for at least one of said pilot valve means.

12. Apparatus as defined in claim 7, further comprising fluid-operated actuating means for at least one of said pilot valve means.

13. Apparatus as defined in claim 7, further comprising mechanical actuating means for at least one of said pilot valve means.

14. Apparatus as defined in claim 1, wherein said housing has a blind bore having an open end and defining a seat at said open end, and wherein said regulating means has bore means connecting said pilot valve means with said chamber and said means for reducing the rate of fluid flow from said chamber comprising a second valve member forming part of said check valve means and movable from a sealing position engaging said seat to thereby interrupt the flow of fluid in said bore means.

Claims

1. Apparatus for controlling the flow of pressurized hydraulic fluid to fluid consumer motors, particularly to consumer motors mounted on or towed by an agricultural vehicle, comprising first and second consumer motors; a source of pressurized fluid; a housing including means defining an inlet connected to said sourcE and first and second outlets respectively connected with said first and second fluid consumer motors; a reservoir; a distributor valve interposed between said inlet and said outlets and having a valve member movable between a plurality of positions including a predetermined position in which pressurized fluid is free to flow from said inlet towards said first outlet, said valve member being arranged to establish a path for the flow of fluid from said inlet to said second outlet in at least some other positions thereof; and regulating means for initiating the movements of said valve member and for controlling the speed of movement of said valve member toward said predetermined position, said regulating means comprising a control chamber, a pilot valve means actuatable to connect said chamber with said reservoir or with said source to thereby respectively effect a movement of said valve member to and from said predetermined position, and check valve means interposed between said distributor valve and said first outlet and movable between a closed position in which it prevents flow of pressurized fluid from said distributor valve to said first outlet and an open position in which it permits flow of pressurized fluid from said distributor valve to said first outlet, said check valve means being biased to said closed position thereof and moved by pressurized fluid from said closed to said open position thereof when said valve member of said distributor valve is in said predetermined position in which pressurized fluid is free to flow from said inlet through said distributor valve towards said first outlet; and flow reducing means for reducing the rate of fluid flow from said control chamber to said reservoir while said pilot valve means is actuated to connect said control chamber with said reservoir, said flow reducing means being movable between an inoperative position in which it does not affect the flow of fluid from said control chamber to said reservoir and an operative position in which it reduces the rate of flow of fluid from said control chamber to said reservoir, said flow reducing means being connected to said check valve means in such a manner so as to be moved into operative position when said check valve means is in open position and to be moved into inoperative position when said check valve means is in closed position.

3. Apparatus as defined in claim 2, wherein said means for gradually reducing the rate of fluid flow to said second outlet comprises a piston having at least one peripheral notch.

9. Apparatus as defined in claim 8, wherein said fluid discharging valve means comprises a housing having a fluid-filled second bore for said second valve member, said second valve member having a passage connecting said first mentioned bore with said second bore and said fluid discharging valve means further comprising an apertured valve plate provided in said second valve member to regulate the flow of fluid into and from said second bore and means for biasing said valve plate against a seat provided therefor in said second valve member.