JP4824777B2 - Hydraulic control device with a descent brake valve - Google Patents

Description

  The present invention is a hydraulic control device for controlling an actuator, in particular a hydraulic cylinder, comprising a directional control valve, which comprises a pressure medium source, a tank and the actuator. Descending braking for controlling the outflow of the pressure medium volume flow from one of the contracting pressure chambers is actuated or moved to control the pressure medium connection between the two pressure chambers A control piston or a control spool of the descending brake valve is loaded by the force of a spring in the closing direction, and is loaded by the pressure in the other pressure chamber that is expanded in the opening direction, In this case, in order to recover the pressure medium, the pressure medium volume flow flowing out from the one pressure chamber to be reduced is directed to the other pressure chamber to be enlarged on the upstream side of the descending brake valve. Shunted into through a check valve recovery path or the recovery duct opening, to those of the type adapted to be added to the pressure medium volume flow on the supply side.

  In order to increase the working speed of a hydraulic actuator, for example a hydraulic cylinder, in known means, the pressure medium of the pressure medium volume flow flowing out from the shrinking pressure chamber is supplied to the expanding pressure chamber via the recovery passage. Applied to the pressure medium volume flow. This avoids the occurrence of cavitation in the expanding pressure chamber and allows a high operating speed of the hydraulic cylinder.

  A hydraulic control device for controlling a hydraulic cylinder is known from Komatsu's data brochure “Structure and Function CLSS, Arm regeneration circuit”. The control device has one directional control valve, the valve spool of which is for controlling the pressure medium connection between the pressure medium source, the tank and the two pressure chambers of the hydraulic cylinder. A descent brake valve arranged in the controller parallel to the axis of the directional control valve for controlling the outflow of the pressure medium volume flow in the event of a load drop, The control piston of the descending brake valve is loaded by the force of the spring in the closing direction and is loaded by the pressure in the expanding pressure chamber in the opening direction. For the recovery of the pressure medium, the pressure medium volume flow exiting from the shrinking pressure chamber is collected via a check valve which opens radially towards the expanding pressure chamber and is arranged radially outside the descending brake valve. It is divided into the passage and added to the pressure medium volume flow on the supply side.

  U.S. Pat. No. 5,832,808 also discloses a hydraulic control device for the control of a hydraulic cylinder, which also has one directional control valve, the valve of the directional control valve The spool (valve slider) is actuated for control of the pressure medium connection between the pressure medium source, the tank and the two pressure chambers of the hydraulic cylinder. Even in this configuration, the volume flow of the pressure medium flowing out from the contracting pressure chamber is radially arranged outside the descending brake valve and enters the recovery passageway via the check valve that opens toward the expanding pressure chamber. It is divided and added to the pressure medium volume flow on the supply side.

  As a disadvantage, the above-mentioned type of control device has a large construction space and therefore requires a high technical cost for the production of the casing hole.

  The object of the present invention is to improve the control device so that the structure of the control device is compact, that is to say the construction space is small and the control device can be manufactured at the lowest cost in terms of production technology.

In order to solve the above problems, in the configuration of the present invention, in the control device of the type described at the beginning,
The check valve is incorporated in the valve spool, and in this case, the pressure acting on the lowering brake valve in the opening direction is transmitted via the check valve. As a result, the structure of the control device is extremely compact, and the control device is manufactured at the lowest cost in terms of manufacturing technology.

  In a preferred embodiment of the invention, the control piston of the lower brake valve is arranged coaxially with the check valve and in a common receiving hole of the valve spool. The check valve preferably comprises a single closure, which is biased by a spring, i.e. is preloaded and has a through-hole, so that it is closed The end face of the body defined by the valve seat and the back face of the closure body defining the spring chamber are loaded with pressure in the control chamber of the valve spool. Corresponds to the pressure in the expanding pressure chamber (cylinder chamber) of the actuator (hydraulic cylinder).

  Advantageously, the control chamber of the valve spool is loaded with the pressure in the expanding pressure chamber via at least one lateral hole in the peripheral wall of the valve spool (a hole extending transversely to the axis of the spool). It has become.

  The closing body of the check valve is advantageously formed as a stepped piston and has an annular shoulder (annular step) located on the side facing the valve seat and acting in the opening direction. The annular shoulder is loaded with the pressure of the pressure chamber (annular chamber) that is reduced by the actuator (hydraulic cylinder).

  The annular shoulder of the closure preferably defines a part of an inlet chamber for the check valve, which inlet chamber passes through at least one radial hole in the peripheral wall of the valve spool. It is connected to the return chamber of the valve hole for receiving, and the pressure in the return chamber corresponds to the pressure upstream of the descending brake valve, that is, the return chamber is upstream of the descending brake valve. Pressure is received, that is, pressure on the upstream side of the descending brake valve is acting in the return chamber. In an advantageous embodiment, a restriction is provided upstream of the check valve for the control of the pressure medium volume flow in the recovery passage. In a particularly simple configuration, the restriction is formed by at least one restriction notch that opens into the recovery passage.

  In another advantageous embodiment, the check valve closing body is initially loaded towards the valve seat by the force of a compression spring, the compression spring being on the opposite side of the closing body from the lowering brake valve. The control piston is supported by a closing portion fixed in the receiving hole of the valve spool via a spring on the side opposite to the end surface.

  According to an advantageous embodiment, the end section of the control piston projects into a hole in the closing part and together with the hole defines a spring chamber for the spring.

  In a preferred embodiment of the invention, the control piston of the lower brake valve is formed as a stepped piston. The control piston preferably has an axial bore which defines an end face acting in the opening direction of the control piston (end face on the check valve side) and a spring chamber of the control piston. The back surface acting in the closing direction (the end surface opposite to the check valve) is loaded with the pressure in the control chamber of the valve spool, and this pressure is the pressure in the pressure chamber that the actuator expands. It corresponds to. A restriction is preferably provided in the axial bore of the control piston. The end face acting in the opening direction of the control piston has a larger area than the back face acting in the closing direction of the control piston, whereby the control piston is based on the pressure in the control chamber of the valve spool. The control piston is actuated to the open position against this force. Based on the back surface acting in the closing direction of the control piston, the spring is weak, i.e. it can be configured with small dimensions.

  In an embodiment of the present invention, a circumferential groove (annular groove extending in the circumferential direction) is formed on the outer periphery of the control piston, and the circumferential groove is contracted by the actuator via at least one circumferential wall hole of the valve spool. Loaded by the pressure in the pressure chamber, that is, receiving the pressure in the pressure chamber that is reduced by the actuator, and connected to the outflow chamber through the tank hole in the peripheral wall of the valve spool at the open position of the control piston. As a result, the pressure medium flows out from the pressure chamber in which the actuator shrinks to the tank.

  In another embodiment of the control device according to the invention, the axial receiving hole of the valve spool is formed as a stepped hole.

  In another embodiment of the control device according to the invention for locking the actuator in a state in which no pressure medium leaks, a load holding valve or an actuator lock valve is arranged in one communication path, in which case the pressure medium The recovery is performed through a receiving hole formed as an axial hole of the valve spool. A theoretical valve is preferably provided in the axial bore of the valve spool, and the spring chamber of the closing body of the theoretical valve (switching valve or logic valve) is in this embodiment the valve in the first operating position of the valve spool. Pressure is released towards the tank via at least one radial hole of the spool, said radial hole being in the valve spool wall (peripheral wall) in another, ie second, operating position of the valve spool. ) So that the theoretical valve is locked (held) in the closed position of the theoretical valve.

Next, the present invention will be described in detail based on the illustrated embodiment. In the drawing
FIG. 1 is a circuit diagram of a hydraulic control device according to the present invention.
2 is a cross-sectional view of the control device of FIG.
3 is a cross-sectional view showing a state in which the valve spool is moved to the right side from the reference position in FIG.
FIG. 4 is an enlarged cross-sectional view of the region of the check valve and the descending brake valve of the direction control valve of FIG.
FIG. 5 is a cross-sectional view showing a state in which the valve spool is moved to the left from the reference position of FIG.
FIG. 6 is a longitudinal sectional view of another embodiment of the hydraulic control device according to the present invention,
FIG. 7 is an enlarged cross-sectional view of the embodiment of FIG. 6 with the valve spool moved to the right.

  FIG. 1 schematically shows a control circuit of a hydraulic control device according to the present invention for controlling an actuator. In this case, the actuator is, for example, a reciprocating operation type of an automobile operating device (not shown). This is a hydraulic cylinder 2. Supply of the pressure medium to the hydraulic cylinder 2 composed of a piston and a cylinder is performed via a pump 4, and the pump is connected via a supply passage (supply line) 6 and a feed passage (feed line) 7. The cylinder chamber (pressure chamber) 8 on the piston side of the hydraulic cylinder 2 is connected. In the supply passage 6, an adjustable metering throttle 10 for controlling the supply of pressure medium is provided between the pump and the cylinder chamber 8. An annular chamber (pressure chamber) 12 on the piston rod side of the hydraulic cylinder 2 is connected to a tank 16 via a return passage (return conduit) 14. In the return passage 14, a continuously adjustable lowering brake valve 20 with a throttle 18 is arranged for controlling the outflow of the pressure medium volume flow from the annular chamber 12 of the hydraulic cylinder 2. The control piston 22 of the valve is loaded in the closing direction by the force of the spring 24 and is caused by the pressure in the cylinder chamber 8 of the hydraulic cylinder 2 via the control passage 26 or, strictly speaking, the pressure in the feed passage 7. Loaded in the opening direction. For recovery, the pressure medium volume flow that flows out of the annular chamber 12 is arranged upstream of the descending brake valve 20 via a check valve 28 that is arranged in the recovery passage 30 and opens toward the expanding cylinder chamber 8. And is added to the pressure medium volume flow on the supply side to the cylinder chamber 8. As a result, the occurrence of cavitation in the cylinder chamber 8 which increases during the running stroke of the hydraulic cylinder 2 is avoided, and a high operating speed (working speed) is made possible. An adjustable throttle 32 is disposed in the collection passage 30 upstream of the check valve 28.

  FIG. 2 shows a specific configuration of the first embodiment of the control device 1 according to the present invention shown in FIG. The control device includes a directional control valve 34. The directional control valve 34 is a valve hole 36 formed in a valve casing 35, and a valve guided to be slidable in the longitudinal direction in the valve hole (perforation). A spool 38 is provided. The directional control valve 34 has a directional control portion 40 and a speed control portion 42, which controls or regulates the pressure medium flow direction and the pressure medium volume flow relative to the hydraulic cylinder. It has become. The valve hole 36 of the directional control valve 34 is sequentially arranged from the left side to the right side in the drawing in the downstream of the outflow chamber 44, the feed chamber 46, and a pressure balance portion (pressure balance portion) 48 schematically shown. (Pressure balance chamber) 50, compensation chamber 52, connection chamber 54 disposed upstream of the pressure balance portion 48, inflow chamber 56, another pressure balance chamber 58 disposed upstream of the pressure balance portion 48, return A chamber 60 and another outflow chamber 62 are enlarged in the radial direction. The pressure medium volume flow is kept constant by the metering restrictor 10 based on the pressure balance unit 48 without depending on the load. The chambers 44 to 62 are partitioned from each other by annular ribs (annular ridges or annular webs) 64 to 82 in the valve holes of the valve casing 35. Both outflow chambers 44 and 62 are connected to the tank connection portion T, and the inflow chamber 56 is connected to the pressure connection portion P. The feed chamber 46 is connected to the operation connection portion A, and the pressure medium is sent from the operation connection portion A to the cylinder chamber 8 of the hydraulic cylinder 2 shown in FIG. The return chamber 60 is connected to the operation connection B, and the pressure medium is sent from the operation connection B to the annular chamber 12 of the hydraulic cylinder 2 in FIG. Both pressure balance chambers 50, 58 are connected to a pressure balance outlet P ″ via a communication passage (balance passage) 84, so that the same pressure acts on both pressure balance chambers 50, 58. The connection chamber 54 is connected to the pressure balance inlet P ′.

  One feed control groove 86, two connection control grooves 88, 90 and one return control groove 92 are provided on the outer periphery of the valve spool 38, and these grooves are annular collars (annular ridges or annular ribs) 94-102. It is defined by. A control edge is formed by a precision control notch (fine control notch) 104 in the return control groove 92, and opening / closing control of a connection portion between the return chamber 60 and the pressure balance chamber 58 is performed via the control edge. It is like that. Two control edges 106 and 108 are formed by the feed control groove 86. The connection between the feed chamber 46 and the pressure balance chamber 50 is controlled to be opened and closed via the control edge 108, whereas the feed chamber 46 and the outflow chamber 44 are connected via the control edge 106. Opening and closing control is performed on the connection portion between the two. The control edges 106 and 108 each have a precision control notch 110. Inflow control edges 112 and 114 are formed on the annular end faces adjacent to the connection control groove 88 and the connection control groove 90, and the inflow control edges are provided with fine control notches 116 and 118, respectively. The notch together with the annular rib 74 forms the metering throttle 10 shown in FIG. 1, which is controlled by the axial movement of the valve spool 38 from the reference position shown in the drawing to the left or right. The connection portion between the inflow chamber 56 and the connection chamber 54, and thus the pressure balance portion 48 is controlled to be opened (open control). At the reference position (intermediate position) of the control spool 38 shown in FIG. Has been.

  In FIG. 3, the valve spool 38 of the directional control valve 34 is shown moved to the right side from the reference position in FIG. 2, ie, in one operating position, in which it is connected to the pressure connection P. The connecting portion between the inflow chamber 56 and the connection chamber 54 is controlled to be opened by the metering throttle 10 (annular collar 98). In this case, the opening control is performed through the precision control notch 116. It has become. The pressure medium flows from the pressure connection portion P into the connection chamber 54 through the inflow chamber 56 and the opening-controlled metering throttle 10, and from there, the pressure balance chambers 50, 58 through the pressure balance portion 48 and the communication passage 84. It comes to flow in. The annular collar 96 is moved to the right side by the axial movement of the valve spool 38, and as a result, the connection between the pressure balance chamber 50 and the feed chamber 46 is controlled to open via the feed control groove 86. Thus, the pressure medium flows to the cylinder chamber 8 of the hydraulic cylinder 2 shown in FIG. In order to control the outflow of the pressure medium volume flow from the annular chamber 12 of the hydraulic cylinder 2 during the downward load with a pulling action, the downward brake valve 20 is arranged in correspondence with the direction control valve 34, and the downward brake valve is controlled. The piston 22 is loaded in the closing direction by the force of the spring 24 and is loaded in the opening direction by the pressure in the cylinder chamber 8. In this case, the pressure of the lower braking valve 20 is recovered for the recovery of the pressure medium. The pressure medium volume flow flowing out on the upstream side is diverted into the recovery passage 30 (see FIG. 1) via the check valve 28 that opens toward the cylinder chamber 8, and the pressure medium volume on the feed side (supply side). It has been added to the flow. The check valve 28 is incorporated in the valve spool 38 according to the present invention. In this case, the pressure acting on the lower brake valve 20 in the opening direction is transmitted via the check valve 28. In the illustrated embodiment of the present invention, the control piston 22 of the lower brake valve 20 is disposed coaxially with the check valve 28 in a receiving hole 122 extending in the axial direction (longitudinal direction) of the valve spool 38. The receiving hole is formed as a common stepped stop hole (bag hole) 120 and opens on the right end surface 124 of the valve spool 38 in FIG.

  As shown in FIG. 4 which shows the directional control valve 34 in an enlarged manner in the area of the check valve 28 and the descending brake valve 20, the check valve 28 includes a single closing body 126. An initial load (preload or bias) is applied toward the valve seat 128 of the valve spool 38 and has a through-hole 130, so that an end face 132 defined by the valve seat 128, and The back surface 136 that defines the spring chamber 134 is loaded with the pressure in the control chamber 138 of the blind hole 120 of the valve spool 38. The control chamber 138 is provided in the peripheral wall (valve spool peripheral wall) of the valve spool 38 and is connected to the cylinder chamber 8 of the hydraulic cylinder 2 via a peripheral groove 140 of the valve spool 38 and a lateral hole 142 that opens to the pressure balance chamber 58. It is designed to be loaded with the internal pressure. In the illustrated operating position that is moved to the right side of the valve spool 38, the connection between the pressure balance chamber 58 and the stop hole 120 is controlled to open by a lateral hole (radial hole) 142.

  The closing body 126 of the check valve 28 is formed as a stepped piston and has an annular shoulder 146 that is disposed on the side facing the valve seat 128 and acts in the opening direction. The annular shoulder (annular step) 146 has a hydraulic pressure via a radial hole 148, a throttle notch 150 that opens into the radial hole and forms an adjustable throttle 32 (FIG. 1), and a return chamber 60. The cylinder 2 is loaded with the pressure in the annular chamber 12. The annular shoulder 146 defines a check valve inlet chamber 152 that is connected to the return chamber 60 via a radial bore 148 and an adjustable or variable throttling 32. The return chamber is affected by the pressure upstream of the lowering brake valve 20. The through-hole 130 of the closing body 126 has a radial extension on the bottom side, that is, on the side opposite to the valve seat or the side opposite to the annular shoulder, and the radial surface of the extension (End face) supports the first end of the compression spring 154. The second end of the compression spring 154 is supported by an annular surface 156 on the end face side of the control piston 22, which extends into the spring 24 with a stepped end section 158, The spring is supported on the one hand on the step of the end section and on the other hand on the closing part 160. The closed portion 160 is screwed into the stop hole 120 at one end and abuts against the stopper shoulder 164 of the valve spool 38 with an annular flange 162.

  The control piston 22 of the lowering brake valve 20 is formed as a stepped piston and enters into the hole 168 of the closing part 160 with the end section 166 and together with the hole defines the spring chamber 170 of the spring 24. It is made. The control piston 22 has a radially protruding stopper collar 174 which is defined on the one hand by the radial shoulder 178 of the valve spool 38 and on the other hand by the annular end face 182 of the closing part 160. The axial movement of the control piston 22 is thus defined by the radial shoulder 178 or the annular end face 182. The control piston 22 is initially loaded by the spring 24 in the closing direction toward the radial shoulder 178 of the stepped stop hole 120, in which case the stopper face 176 of the stopper collar 174 of the control piston is It comes into contact with the radial shoulder 178 of the blind hole 120. In the open direction, the stopper collar 174 is brought into contact with the annular end surface 182 of the closing part 160 with another stopper surface 180. The receiving chamber for the stopper collar 174 is connected to the return chamber 62 via an obliquely extending tank hole 184 in the peripheral wall of the valve spool in the illustrated operating position, which is moved to the right side of the valve spool 38, to the tank. The load has been reduced. The control piston 22 has an axial hole 186 that opens into the spring chamber 170 through a throttle hole 187. Thereby, the end surface 156 acting in the opening direction and the stepped back surface 188 defining the spring chamber 170 and acting in the closing direction are loaded by the pressure in the control chamber 138 of the valve spool 38; The pressure corresponds to the pressure in the cylinder 8, so that the spring 24 is assisted by the force acting on the back surface 188 of the control piston 22, and therefore the tank pressure in the spring chamber 170. As compared with the case where the above-mentioned is effective, the weak spring 24 can be used. The end surface 156 acting in the opening direction of the control piston 22, that is, the front surface, has a larger area than the back surface 188, so that the control piston 22 is moved to the open position against the force of the spring 24. It is like that. A circumferential groove 190 is formed on the outer periphery of the control piston 22, and the circumferential groove is connected to the return chamber 60 via a peripheral wall hole 192 in the valve spool peripheral wall, and the control piston 22 is moved to the right side. 1 is connected to the outflow chamber 62 through an obliquely extending tank hole 194 in the peripheral wall of the valve spool. As a result, the pressure medium is transferred from the annular chamber 12 of the hydraulic cylinder 22 shown in FIG. It is designed to flow in. In this case, the diaphragm cross section of the descending brake valve 20 is defined using the diaphragm edge defined (formed) by the end surface 191 of the circumferential groove 190.

  FIG. 5 shows the valve spool 38 moved to the left side from the reference position in FIG. 2, that is, in another operating position, in which the inflow chamber 56 passes through the metering restrictor 10. The connection to the connection chamber 54 is similarly controlled to open, and as a result, the pressure balance chambers 50 and 58 are supplied with a pressure medium. The pressure balance chamber 58 is connected to the return chamber 60 via the precision control groove 104. As a result, the annular chamber 12 of the hydraulic cylinder 2 in FIG. 1 is supplied with a pressure medium. The feed chamber 46 is connected to the outflow chamber 44 via the precision control notch 110. As a result, the load on the cylinder chamber 8 is reduced (releasing pressure) toward the tank 16 (FIG. 1). The hydraulic cylinder 2 is run-in, i.e. the piston rod runs into the cylinder.

  Next, the function of the control device 1 according to the first embodiment of the present invention will be described with reference to FIGS.

  At the reference position (intermediate position or neutral position) shown in FIG. 2 of the valve spool 38, the pressure connection portion P and the operation connection portions A and B are cut off. Assume that the valve spool 38 is moved to the right from the reference position in FIG. 3 and 4 showing the valve spool 38 axially moved to the right side, the connection portion from the inflow chamber 56 connected to the pressure connection portion P to the connection chamber 54 based on the axial movement of the valve spool 38. Is controlled by the metering throttle 10 (annular collar 98). In this case, the opening control is performed through the precision control notch 116. The pressure medium flows into the connection chamber 54 from the pressure connection portion P through the inflow chamber 56 and the metering throttle 10 that is controlled to be opened, and then through the pressure balance portion 48 and the communication passage 84 to the pressure balance chambers 50 and 58. It comes to flow in. Based on the axial movement of the valve spool 38, the annular collar 98 is also moved to the right side. As a result, the connection from the pressure balance chamber 50 to the feed chamber 46 is controlled to open by the feed control groove 86. The pressure medium flows through the feed chamber 46 and the working connection A to the cylinder chamber 8 of the hydraulic cylinder 2 shown in FIG. The hydraulic cylinder 2 runs out, i.e. the piston rod runs out of the cylinder. When the pressure acting in the control chamber 138 via the lateral hole 142 exceeds the pressure defined by the force of the spring 24, the control piston 22 of the lowering brake valve 20 is moved to the annular surface (end surface) 156 and the rear surface 188. As a result, the return chamber 60 is moved through the return control groove 92, the peripheral wall hole 192, and the peripheral groove 190 of the control piston 22 against the force of the spring 24. The tank hole 194 is connected to the outflow chamber 62 through the tank hole. The annular chamber 12 of the hydraulic cylinder 2 is released toward the tank 16 (FIG. 1) via the opened lower braking valve 20, that is, the load is reduced.

  In the case of a load causing a pulling action, that is, a descending load, the pump 4 cannot discharge a sufficient pressure medium into the expanding cylinder chamber 8 of the hydraulic cylinder 2, and as a result, the pressure in the cylinder chamber 8 is annular. The pressure is lower than the pressure in the chamber 12. The decreasing pressure in the cylinder chamber 8 acts in the control chamber 138 via the lateral hole 142. As a result, the control piston 22 of the lowering brake valve 20 is closed by the force of the spring 24, and the hydraulic cylinder The connection portion from the two annular chambers 12 to the tank 16 is closed (see FIG. 1). The pressure medium returned from the contracting annular chamber 12 of the hydraulic cylinder 2 flows into the return chamber 60 via the actuating connection B, and as a result, the annular shoulder 146 of the check valve closure 126. Is loaded with pressure in the annular chamber 12 of the hydraulic cylinder 2 via the radial hole 148 and the inlet chamber 152. When the pressure loading the annular shoulder 146 of the closing body 126 exceeds the spring force of the compression spring 154, the closing body is opened against the spring force, so that the pressure medium radiates from the return chamber 60. It flows into the communication path 84 through the direction hole 148, the control chamber 138, the lateral hole 142, and the pressure balance chamber 58, and is added to the pressure medium volume flow on the supply side to the cylinder chamber 8 of the hydraulic cylinder 2 (pressure). Medium recovery). As a result, in the case of a descending load, the occurrence of cavitation in the expanding cylinder chamber 8 is avoided, and a high running speed (operation speed) is made possible. In this case, the throttle notch 150 provided in the valve spool 38 defines the flow rate of the recovered pressure medium flow within a small flow rate range.

  The valve spool 38 is moved from the reference position shown in FIG. 2 to the left side, that is, to the operating position shown in FIG. In the operating position, the connection from the inflow chamber 56 to the connection chamber 54 via the metering throttle 10 is controlled to open, and as a result, the pressure balance chambers 50 and 58 are supplied with a pressure medium. . The pressure balance chamber 58 is connected to the return chamber 60 via the precision control groove 104 and the return control groove 92. As a result, the annular chamber 12 of the hydraulic cylinder 2 supplies the pressure medium via the operation connection B. It has come to be. The feed chamber 46 is connected to the outflow chamber 44 via the feed control groove 86 and the precision control notch 110, and as a result, the cylinder chamber 8 is released toward the tank 16 via the operation connection B. . The hydraulic cylinder 2 can be run in without a pressure medium being collected.

  In order to lock the hydraulic cylinder 2 in a state where the pressure medium does not leak, the control device according to the present invention shown in FIGS. 2 to 5 prevents the pressure medium flow from the hydraulic cylinder 2 to the tank 16. That is, an openable load holding valve 196 for shutting off must be provided.

  FIG. 6 is a longitudinal sectional view of a directional control valve 198 of an embodiment according to the present invention for locking the hydraulic cylinder 2 loaded with a descending load F. FIG. The basic configuration of the directional control valve 198 corresponds to the configuration of the valve shown in FIGS. 2 to 5, that is, in the case of this variation, the check valve 28 and the lowering brake valve 20 are coaxial with the valve spool 38. In principle, these components have the same configuration as in the previous embodiment. This variation differs from the previous embodiment in the following points, that is, in the communication path 84 downstream of the pressure balance 48 and toward the pressure balance 48 for locking the hydraulic cylinder 2 respectively. A load holding valve 196 for closing is provided. Since the recovery of the pressure medium is not performed via the communication path 84 based on the load holding valve (check valve) 196 in the modified example, the valve spool 38 is consistently extended and stepped in the modified example. In the illustrated operating position provided with an axial bore 200 and moved to the left side of the valve spool 38, the pressure medium passes from the annular chamber 12 through the return passage 14, the return chamber 60, the lateral hole 142 and the theoretical valve 202. The check valve 28 opened by the annular shoulder 146 and the axial hole 200 are led to the feed chamber 46. On the side of the feed chamber 46, the axial hole 200 is defined by a closing screw 204 screwed into the valve spool 38, which supports the closing body 208 of the theoretical valve 202 via a spring 206. On the other hand, the check valve 28 and the lowering brake valve 20 are provided on the return chamber 60 side as described above. The closing body 208 of the theoretical valve 202 is initially loaded toward the valve seat 210 and has a throttle hole 212, thus defining an end face 213 and a spring chamber 214 defined by the valve seat 210. The back surface 216 is loaded with the pressure in the axial hole 200 of the valve spool 38. The closing body 208 of the theoretical valve 202 is formed as a stepped piston, and has an annular surface 218 that is disposed on the valve seat side and acts in the opening direction, and the annular surface is the actuating connection portion A and the peripheral wall hole 220. The pressure is applied by the pressure of the expanding cylinder chamber 8 of the hydraulic cylinder 2. The spring chamber 214 of the closure 208 is moved to the left side of the valve spool 38 via the gap 222 and the radial hole 224 between the axial hole 200 and the outer periphery of the closure screw 204 in the illustrated operating position. As a result, the theoretical valve 202 is released toward the outflow chamber 62 by the pressure generated in the feed chamber 46 or the axial hole 200 and loading the annular surface 218 and the end surface 213. It is moved to the open position against the force of

  In FIG. 7, in which the valve spool 38 is moved to the right, ie, enlarged in the region of the theoretical valve 202 in the right operating position, the radial hole 224 is in the operating position at the wall 226 of the valve hole 36. Closed by. Therefore, the theoretical valve 202 is shut off and is not controlled to open via the radial shoulder 218 by the pressure medium volume flow flowing out of the actuation connection A through the feed control groove 86 toward the tank 16 (FIG. 1). It is like that. In the operating position, the feed chamber 46 is connected to the outflow chamber 62 via a precision control notch 228 that opens into the feed control groove 86.

  The disclosed hydraulic control device for the control of the actuator, in particular for the control of the hydraulic cylinder 2, comprises directional control valves 34, 198, the valve spool 38 of which is a pressure medium source. 4 is operated (moved) to control the pressure medium connection between the tank 16 and the two pressure chambers 8 and 12 of the actuator or hydraulic cylinder 2, A descending brake valve 20 for controlling the outflow of the pressure medium volume flow from the pressure chamber 12 is provided, and the control piston 22 of the descending brake valve is loaded by the force of a spring 24 in the closing direction and the expansion in the opening direction. The pressure medium volume flow flowing out of the one pressure chamber to be reduced for the recovery of the pressure medium is applied to the pressure-reducing braking valve 20 by the pressure in the other pressure chamber 8. On the upstream side, the flow is branched (branched) into the recovery passage 30 via the check valve 28 that opens toward the other pressure chamber 8 that is expanded, and is added to the pressure medium volume flow on the supply side. . According to the present invention, the check valve 28 is incorporated in the valve spool 38, and the pressure applied to the lowering brake valve 20 in the opening direction is transmitted through the check valve 28.

Circuit diagram of hydraulic control device according to the present invention Sectional view of the control device of FIG. Sectional drawing which shows the state which moved the valve spool to the right side from the reference position of FIG. 3 is an enlarged cross-sectional view of the check valve and descending brake valve region of the directional control valve of FIG. Sectional drawing which shows the state which moved the valve spool to the left side from the reference position of FIG. Longitudinal sectional view of another embodiment of the hydraulic control device according to the present invention FIG. 6 is an enlarged cross-sectional view showing the valve spool moved to the right in the embodiment of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Control apparatus, 2 Hydraulic cylinders, 4 Pumps, 6 Supply passages, 7 Feed passages, 8 Cylinder chambers, 10 Metering throttles, 12 Annular chambers, 14 Return passages, 16 Tanks, 18 throttles, 20 Decreasing brake valves, 22 Control Piston (control spool), 24 spring, 28 check valve, 30 recovery passageway, 34 direction control valve, 35 valve casing, 36 valve hole, 38 valve spool, 40 direction control part, 42 speed control part, 44 outflow chamber, 46 Feed chamber, 48 Pressure balance section, 50 Pressure balance chamber, 52 Compensation chamber, 54 Connection chamber, 56 Inflow chamber, 58 Pressure balance chamber, 60 Return chamber, 62 Outflow chamber, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82 annular rib, 84 communication path, 86 feed control groove, 88, 9 Connection control groove, 92 Return control groove, 94, 96, 98, 100, 102 Annular collar, 104 Precision control notch, 106, 108 Control edge, 112, 114 Inflow control edge, 116, 118 Precision control notch, 122 Receiving Hole, 124 end face, 126 closing body, 128 valve seat, 130 through hole, 132 end face, 134 spring chamber, 136 back surface, 138 control chamber, 140 circumferential groove, 146 annular shoulder, 148 radial hole, 150 throttle notch, 152 inlet chamber, 154 compression spring, 156 annular surface, 158 end section, 160 closing portion, 162 flange, 164 stopper shoulder, 166 end section, 168 hole, 170 spring chamber, 174 stopper collar, 176 stopper surface, 178 Radial shoulder, 180 s Upper surface, 182 annular end surface, 184 tank hole, 186 axial hole, 187 throttle hole, 188 rear surface, 190 circumferential groove, 192 circumferential wall hole, 191 end surface, 194 tank hole, 196 load holding valve, 198 direction control valve, 200 axis Directional hole, 202 theoretical valve, 204 closing screw, 206 spring, 208 closing body, 210 valve seat, 212 throttle hole, 213 end face, 214 spring chamber, 216 back surface, 218 annular surface, 220 peripheral wall hole, 224 radial hole, 228 Precision control notch, A working connection, P pressure connection, P 'pressure balance inlet, P "pressure balance outlet, T tank connection

Claims (17)

A control apparatus for hydraulic for the control hydraulic cylinder (2) provided with a directional control valve (34,198), the valve spool of the directional control valve (38) is a pressure medium source (4 ), The tank (16) and the pressure medium connection between the two pressure chambers (8, 12) of the hydraulic cylinder (2). And a lower brake valve (20) for controlling the discharge of the pressure medium volume flow from the two pressure chambers (12). The control piston (22) of the lower brake valve is closed by the force of the spring (24) in the closing direction. The pressure medium volume flow which is loaded and is loaded by the pressure in the further expanding pressure chamber (8) in the opening direction and flows out of the contracting pressure chamber for the recovery of the pressure medium. On the upstream side of the descending brake valve (20), In a type which is diverted into the recovery passageway (30) via a check valve (28) which opens toward the larger pressure chamber (8) and added to the pressure medium volume flow on the supply side The check valve (28) is incorporated in the valve spool (38), and the pressure acting on the lower brake valve (20) in the opening direction is transmitted via the check valve (28). For this purpose, the control piston (22) of the lower brake valve (20) is coaxial with the check valve (28) and is common to the valve spool (38). Arranged in one receiving hole (122), the check valve (28) includes a closure (126), which is initially loaded and has a through hole (130). And consequently the end face defined by the valve seat (128) 132) and the back surface (136) defining the spring chamber (134) are loaded with pressure in the control chamber (138) of the valve spool (38), A hydraulic control device for controlling an actuator, which corresponds to the pressure in the expanding pressure chamber (8) .   The control chamber (138) according to claim 1, wherein the control chamber (138) is loaded with pressure in the expanding pressure chamber (8) via at least one lateral hole (142) in the peripheral wall of the valve spool. Control device. The closure body (126) is formed as a stepped piston and has an annular shoulder (146) arranged on the side facing the valve seat (128) and acting in the opening direction. a control device according to claim 1 or 2 adapted to be loaded with a pressure reduction to the pressure chamber (12). The annular shoulder (146) defines an inlet chamber (152) for the check valve, which is connected via the at least one radial hole (148) in the peripheral wall of the valve spool to the valve spool (148). 38) is connected to the return chamber (60) of the valve hole (36) for receiving the pressure, and the pressure on the upstream side of the descending brake valve (20) is applied to the return chamber. Item 4. The control device according to Item 3 . The control device according to any one of claims 1 to 4 , wherein a throttle (32) is connected upstream of the check valve (28). 6. Control device according to claim 4 and 5 , wherein the restriction (32) is formed by at least one restriction notch (150) opening into the radial hole (148). The closing body (126) is initially loaded toward the valve seat (128) by the force of the compression spring (154), which is applied to the end face of the control piston (22) of the lower brake valve (20). and supported, the control piston via a spring (24), any one of claims 1, which is supported on a fixed closure portion into the receiving hole (122) of the valve spool (160) 6 The control device described in 1. The end section (156) of the control piston (22) protrudes into a hole (168) in the closure portion (160) and together with the hole defines a spring chamber (170) for the spring (24). The control device according to claim 7 formed. Control device according to any one of the control piston of the descending braking valve (20) (22) from claim 1, which is formed as a stepped piston 8. The control piston (22) has an axial bore (186), so that an end face (156) acting in the opening direction of the control piston and a spring chamber (170) of the control piston are defined. The back surface (188) acting in the closing direction is loaded with the pressure in the control chamber (138) of the valve spool (38), and the pressure is increased in the expanding pressure chamber (8). The control device according to claim 9 , which corresponds to a pressure of 11. Control device according to claim 10 , wherein a restriction (187) is provided in the axial bore (186) of the control piston (22). 12. Control device according to claim 10 or 11 , wherein the end face (156) acting in the opening direction of the control piston (22) has a larger area than the back face (188) acting in the closing direction of the control piston. . A circumferential groove (190) is formed on the outer periphery of the control piston (22), and the circumferential groove is provided in the pressure chamber (12) to be reduced in the actuator (2) via at least one circumferential wall hole (192). It is loaded with pressure and is connected to the outflow chamber (62) via a tank hole (194) in the peripheral wall of the valve spool at the open position of the control piston (22). The control device according to any one of claims 1 to 12 , wherein the pressure medium flows out from the pressure chamber (12) to be reduced to the tank (16). Receiving hole (122) is control device according to any one of claims 1, which is formed as a stepped bore (120) 13. Load holding valve in the communication passage (84) in (196) the Yes disposed, recovery, claim 1 adapted to be carried through a receiving hole which is formed as a longitudinal bore (200) (122) 14. The control device according to any one of 1 to 13 . 16. The control device according to claim 15 , wherein a theoretical valve (202) is provided in the axial hole (200). The spring chamber (214) of the closure (208) of the theoretical valve (202) is released toward the tank via at least one radial hole (224) in the first operating position of the valve spool (38). The radial hole is adapted to be closed by a wall (226) of the valve hole (36) in another operating position of the valve spool (38), the theoretical valve (202) 17. The control device according to claim 16 , wherein the control device is locked in a closed position of the theoretical valve.

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