JP2005220530A - Controller for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a working vehicle capable of securing favorable workability in the case of working and absorbing of the pressure variation of a hydraulic cylinder in the case of traveling without having such a branch passage that it is branched from a discharge pipe line of a main pump or a main pipe line communicated with the discharge pipe line and that it is directly connected to a pressure reducing valve. <P>SOLUTION: The controller for the working vehicle is equipped with a boom cylinder 2, an accumulator 5 connected to the boom cylinder 2, an opening and closing valve 7 placed between the boom cylinder 2 and the accumulator 5, communicating the boom cylinder 2 with the accumulator 5 at an opening position A2 and shutting the boom cylinder 2 from the accumulator 5 at a closing position A1, a switching means switching the opening and closing valve 7, the pressure reducing valve keeping pressure in the accumulator 5 in predetermined pressure and a check valve 15 preventing a backflow of pressure oil from the accumulator 5 side and, the switching means includes a pilot passage 10 leading the pressure of the boom cylinder 2 as the switching signal pressure of the opening and closing valve 7 without making the pressure reducing valve 14 intervene. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control device for a work vehicle that includes an accumulator that absorbs pressure fluctuations of a traveling hydraulic cylinder.

  There exists a thing shown by patent document 1 as this type of prior art. This prior art is arranged between a hydraulic cylinder, for example, a boom cylinder, an accumulator connected to the boom cylinder, and a bottom chamber and an accumulator of the boom cylinder. And an opening / closing valve for shutting off the bottom chamber from the accumulator, and switching means for switching the opening / closing valve.

  The switching means includes a pilot valve having a first switching position for supplying a pilot pressure to the control port of the on-off valve and a second switching position for blocking the supply of the pilot pressure, that is, an electromagnetic valve, and a pilot valve for the electromagnetic valve. In addition to supplying pressure, pilot pressure is supplied to the accumulator described above, and a pressure reducing valve that maintains the pressure in the accumulator at a predetermined pressure and a discharge line of the main pump, or pressure oil is supplied to the boom cylinder. And a branch passage branched from the leading main pipe and directly connected to the pressure reducing valve.

  In addition, a check valve for preventing a back flow from the accumulator side is disposed in a pipe line connecting the accumulator and the pressure reducing valve. Further, a vehicle speed sensor that detects whether or not the vehicle speed is equal to or higher than a predetermined speed, and a controller that controls switching of the above-described electromagnetic valve in accordance with a signal output from the vehicle speed sensor are provided.

  In this prior art, the pilot pressure discharged from the main pump, guided by the branch passage, and reduced by the pressure reducing valve is supplied to the control port of the on / off valve by switching the electromagnetic valve to the first switching position. Thus, the on-off valve is switched to the closed position. Therefore, the bottom chamber of the boom cylinder is shut off from the accumulator, the undesired operation of the boom cylinder due to the pressure difference between the pressure of the bottom chamber and the accumulator is suppressed, and the boom cylinder is smoothly driven for good workability. It can be secured.

  During traveling, the solenoid valve is switched to the second switching position, whereby supply of pilot pressure to the control port of the on / off valve via the branch passage is blocked, and the on / off valve is switched to the open position. Therefore, the bottom chamber of the boom cylinder communicates with the accumulator, and the pressure fluctuation in the bottom chamber of the boom cylinder during traveling is absorbed by the accumulator. As a result, vibrations of the work implement such as the boom and the vehicle body accompanying the pressure fluctuation in the bottom chamber described above are suppressed.

Further, when the on-off valve is switched from the closed position to the open position in accordance with the transition from the working state to the traveling state, for example, the accumulator in which the pressure oil in the bottom chamber of the boom cylinder, which is at a high pressure, forms the low pressure side The pressure reducing valve functions so as to prevent the operation of the boom cylinder due to instantaneous flow, that is, the lowering of the boom. That is, the pressure in the accumulator is maintained at a pressure that is not significantly lower than the predetermined pressure, that is, the bottom pressure of the boom cylinder, by the pressure reducing valve. Thereby, at the time of transition from the working state to the traveling state, a large amount of pressure oil flows from the bottom chamber of the boom cylinder to the accumulator, and the operation of the boom cylinder at the time of transition is suppressed.
JP 2000-309953 A

  The above-described prior art includes a branch passage branched from the main pump discharge line or the main pipe communicating with the discharge pipe, and directly connected to the pressure reducing valve. The branch passage has an independent structure. Since it is produced by the long hose to form, an apparatus structure tends to become complicated. In addition, since a hose must be provided, there is a problem that the manufacturing cost is high and the overall piping design is difficult.

  The present invention is made from the actual situation in the above-described prior art, and its purpose is to branch from the discharge line of the main pump or from the main line communicating with the discharge line and to be directly connected to the pressure reducing valve. An object of the present invention is to provide a work vehicle control device that can achieve good workability during work and absorb pressure fluctuations of a hydraulic cylinder during travel without providing a passage.

  To achieve the above object, the present invention provides a hydraulic cylinder, an accumulator connected to the hydraulic cylinder, the hydraulic cylinder and the accumulator, and communicates the hydraulic cylinder to the accumulator in an open position. On-off valve that shuts off the hydraulic cylinder from the accumulator in the closed position, switching means for switching the on-off valve, a pressure reducing valve that maintains the pressure in the accumulator at a predetermined pressure, and a backflow of pressure oil from the accumulator side. In the work vehicle control device including a check valve for blocking, the switching means includes a pilot passage that guides the pressure of the hydraulic cylinder as a switching signal pressure of the on-off valve without interposing the pressure reducing valve. It is said.

  In the present invention configured as described above, during operation, the pressure of the hydraulic cylinder is guided as a switching signal pressure to the on-off valve via the pilot passage, whereby the on-off valve is switched to the closed position, and the hydraulic cylinder is connected to the accumulator. Is cut off from. As a result, undesired operation of the hydraulic cylinder due to the differential pressure between the pressure of the hydraulic cylinder and the pressure of the accumulator can be suppressed, and the hydraulic cylinder can be smoothly driven to ensure good workability.

  During traveling, the function of the switching means prevents the switching signal pressure introduced through the pilot passage from being supplied to the on-off valve, so that the on-off valve is switched to the open position, and the hydraulic cylinder communicates with the accumulator. To do. As a result, the pressure fluctuations of the traveling hydraulic cylinder are absorbed by the accumulator, and the vibration of the work implement driven by the hydraulic cylinder and the vehicle body is suppressed.

  In other words, without providing a branch passage branched from the main pump discharge line or the main pipe communicating with the discharge pipe, the switching signal pressure with respect to the on-off valve guided by the pilot passage ensures good workability during work. Securement and absorption of pressure fluctuations of the hydraulic cylinder during traveling can be realized.

  The pilot passage for guiding the switching signal pressure to the on-off valve can be set to a short passage where one end is connected to a pipe line connecting the hydraulic cylinder and the accumulator and the other end is connected to the control port of the on-off valve.

  According to the present invention, in the above invention, the switching means is provided in the pilot passage, and the switching signal pressure guided to the pilot passage is supplied to the control port of the on-off valve; And an electromagnetic valve having a second switching position for blocking supply of signal pressure to the control port of the on-off valve.

  In the present invention configured as above, the electromagnetic valve is switched to the second switching position during operation, and the supply of the signal pressure guided through the pilot passage to the on-off valve is blocked by the electromagnetic valve. Is switched to the closed position and the hydraulic cylinder is disconnected from the accumulator. Therefore, as described above, undesired operation of the hydraulic cylinder due to the differential pressure between the pressure of the hydraulic cylinder and the pressure of the accumulator is suppressed.

  Further, during traveling, the solenoid valve is switched to the first switching position, the pressure of the hydraulic cylinder is guided as a switching signal pressure to the on / off valve via the pilot passage and the solenoid valve, and the on / off valve is switched to the open position. The hydraulic cylinder communicates with the accumulator. Therefore, as described above, the pressure fluctuation of the traveling hydraulic cylinder is absorbed by the accumulator.

  In the invention described above, the invention includes a vehicle speed sensor that detects whether the vehicle speed is equal to or higher than a predetermined speed, and a controller that controls switching of the electromagnetic valve in accordance with a signal output from the vehicle speed sensor. It is said.

  In the present invention configured as described above, it is detected by a vehicle speed sensor that the vehicle speed does not reach a predetermined speed or higher during work. At this time, the solenoid valve is switched to the first switching position according to the signal output from the vehicle speed sensor, and the on-off valve is switched to the closed position as described above. Further, during traveling, the vehicle speed sensor detects that the vehicle speed is equal to or higher than a predetermined speed. At this time, the solenoid valve is switched to the second switching position in accordance with the signal output from the vehicle speed sensor, and the on-off valve is switched to the open position as described above.

  Further, the present invention is the above invention, wherein the on-off valve has a passage where the closing position of the on-off valve communicates with the hydraulic cylinder, and a flow path that connects the passage at the closed position of the on-off valve and the pressure reducing valve. A feature is that a resistance element is arranged in the flow path.

  In the present invention configured as described above, during operation, the hydraulic cylinder and the pressure reducing valve communicate with each other via a passage in the closed position of the on-off valve, and the pressure of the hydraulic cylinder is higher than the set pressure of the pressure reducing valve, that is, the pressure of the accumulator. In some cases, the pressure oil in the hydraulic cylinder tends to flow into the accumulator via the pressure reducing valve, but since the resistance element is arranged in the flow path between the on-off valve and the pressure reducing valve, It becomes slow and the influence on the operation of the hydraulic cylinder can be reduced. That is, good work can be performed through the operation of the hydraulic cylinder.

  Moreover, the present invention is characterized in that, in the above invention, the check valve is arranged in a portion of the flow path located between the pressure reducing valve and the resistance element.

  Further, the present invention is characterized in that, in the above invention, the resistance element comprises a stop.

  In the present invention, the hydraulic cylinder is a boom cylinder, and the switching signal pressure is a bottom pressure of the boom cylinder.

  The present invention does not include a branch passage branched from the main pump discharge pipe or the main pipe communicating with the discharge pipe, and directly connected to the pressure reducing valve, and according to the switching signal pressure guided by the pilot passage. Thus, the on-off valve is held in the closed position or switched to the open position, so that it is possible to achieve good workability during work and absorption of pressure fluctuations of the hydraulic cylinder during travel. The pilot passage described above can be set to a very short passage where one end is connected to a pipe line connecting the hydraulic cylinder and the accumulator and the other end is connected to the control port of the on-off valve. As a result, the apparatus structure can be simplified as compared with the conventional apparatus, the manufacturing cost can be reduced, and the entire piping design can be facilitated.

  Hereinafter, the best mode for carrying out the working vehicle control apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention. The present embodiment is a control device provided in a work vehicle, for example, a wheel loader.

  As shown in FIG. 1, the present embodiment is a boom having a main pump 1 and a bottom chamber 2a and a rod chamber 2b that are driven by pressure oil discharged from the main pump 1 to drive a working tool such as a boom (not shown). A cylinder 2, a boom direction control valve 3 that controls the flow of pressure oil supplied from the main pump 1 to the boom cylinder 2, and a tank 4 are provided.

  Also, the accumulator 5 connected to the bottom chamber 2a of the boom cylinder 2 and the bottom chamber 2a of the boom cylinder 2 are arranged between the accumulator 5, and the bottom chamber 2a is communicated with the accumulator 5 at the open position A2, and the closed position. On-off valve 7 that shuts off the bottom chamber 2a from the accumulator 5 at A1, a pressure-reducing valve 14 that maintains the pressure in the accumulator 5 at a predetermined pressure, a check valve 8 that prevents backflow of pressure oil from the accumulator 5 side, and on-off And switching means for switching the valve 7.

  The switching means described above is provided in the pilot passage 10 that guides the pressure in the bottom chamber 2a of the boom cylinder 2 as the switching signal pressure of the on-off valve 7 without the pressure reducing valve 14 interposed therebetween. A first switching position B1 for supplying the switching signal pressure led to 10 to the control port 7b of the on-off valve 7, and a second switching position B2 for preventing the above-mentioned switching signal pressure from being supplied to the control port 7b of the on-off valve 7. And a solenoid valve 11 having One end of the pilot passage 10 is connected to a control line 9 a that connects the bottom chamber 2 a of the boom cylinder 2 and the on-off valve 7, and the other end is connected to a control port 7 b of the on-off valve 7. The rod chamber 2b of the boom cylinder 2 and the on-off valve 7 are connected by a control pipe line 9b.

  Further, another control port 7 a that opposes the control port 7 b of the on-off valve 7 is connected to the accumulator 5 through the pilot passage 8. Therefore, the on-off valve 7 is a differential pressure between the pressure of the accumulator 5 guided through the pilot passage 8 and the pressure of the bottom chamber 2a of the boom cylinder 2 guided through the pilot passage 10 and the electromagnetic valve 11, that is, the switching signal pressure. The position is switched to either the closed position A1 or the open position A2 depending on the magnitude relationship between the force due to and the spring force.

  The on-off valve 7 has a passage 7c that communicates with the control line 9a connected to the bottom chamber 2a of the boom cylinder 2 when switched to the closed position A1. That is, when the on-off valve 7 is switched to the closed position A1, the passage 7c of the on-off valve 7 communicates with the control line 9a, the bottom chamber 2a of the boom cylinder 2 is shut off from the accumulator 5, and the boom cylinder 2 The rod chamber 2 b is cut off from the tank 4. When the on-off valve 7 is switched to the open position A2, the bottom chamber 2a of the boom cylinder 2 and the accumulator 5 communicate with each other, and the rod chamber 2b of the boom cylinder 2 and the tank 4 communicate with each other.

  The pressure reducing valve 14 described above shuts off the accumulator 5 from the on-off valve 7, connects the accumulator 5 and the on-off valve 7 to each other, and connects the accumulator 5 to the on-off valve 7. The switching position C2 is cut off, and the position is switched to either the switching position C1 or the switching position C2 depending on the magnitude relationship between the force due to the differential pressure between the pressure of the accumulator 5 and the tank pressure and the spring force.

  A flow path 17 that connects the passage 7 c at the closed position A1 of the on-off valve 7 and the pressure reducing valve 14 is provided, and a resistance element such as a throttle 16 is disposed in the flow path 17. Further, a check valve 15 for preventing the backflow of the pressure oil from the accumulator 5 side described above is arranged in a portion of the flow path 17 located between the pressure reducing valve 14 and the throttle 16.

  The on-off valve 7, the electromagnetic valve 11, the pilot passage 10, the pressure reducing valve 14, the flow path 17, the throttle 16, and the check valve 15 described above are provided in, for example, one valve block 6.

  Further, the present embodiment detects whether or not the vehicle speed is equal to or higher than a predetermined speed that can be regarded as the speed in the traveling state, that is, whether or not the vehicle speed is a speed that does not reach the predetermined speed that can be regarded as the working state. A vehicle speed sensor 13 and a controller 12 that controls switching of the electromagnetic valve 11 in accordance with a signal output from the vehicle speed sensor 13 are provided. When the vehicle speed sensor 13 detects that the vehicle speed does not reach the predetermined speed, the controller 12 outputs a control signal for holding the electromagnetic valve 11 at the first switching position B1 to the control unit of the electromagnetic valve 11. When the vehicle speed sensor 13 detects that the vehicle speed is equal to or higher than the predetermined speed, a control signal for switching the electromagnetic valve 11 from the controller 12 to the second switching position B2 against the spring force is output to the controller of the electromagnetic valve 11. Is done.

  Hereinafter, operations at the time of work, operations at the time of travel, and operations at the time of transition from the work state to the travel state will be described.

  During operation, the vehicle speed sensor 13 detects that the vehicle speed does not reach a predetermined speed, and the controller 12 switches the electromagnetic valve 11 from the controller 12 to the controller of the electromagnetic valve 11 in accordance with a signal output from the vehicle speed sensor 13. A control signal held at the position B1 is output. As a result, the pressure in the bottom chamber 2a of the boom cylinder 2 is guided to the control port 7b of the on-off valve 7 via the pilot passage 10 and the electromagnetic valve 11 as a switching signal pressure. Therefore, the force due to the pressure difference between the pressure of the control port 7a and the pressure of the control port 7b becomes smaller than the spring force, the on-off valve 7 is switched to the closed position A1, and the bottom chamber 2a of the boom cylinder 2 is shut off from the accumulator 5. Is done. Further, the bottom chamber 2 a of the boom cylinder 2 communicates with the pressure reducing valve 17 through the throttle 16 and the check valve 15 through the passage 7 c of the on-off valve 7. Thereby, the undesired operation of the boom cylinder 2 due to the differential pressure between the pressure of the boom cylinder 2 and the pressure of the accumulator 5 is suppressed, and the boom cylinder 2 can be smoothly driven to ensure good workability.

  During this operation, the bottom chamber 2a of the boom cylinder 2 and the pressure reducing valve 14 communicate with each other via the passage 7c at the closed position A1 of the on-off valve 7, and the pressure in the bottom chamber 2a of the boom cylinder 2 is set in the pressure reducing valve 14. When the pressure is higher than the pressure of the accumulator 5, the pressure oil in the bottom chamber 2 a of the boom cylinder 2 tends to flow into the accumulator 5 via the pressure reducing valve 14. Since the throttle 16 is disposed in the flow path 17, the flow of the pressure oil described above becomes slow, and the influence on the operation of the boom cylinder 2 can be reduced. That is, good work can be performed through the operation of the boom cylinder 2.

  Further, during traveling, the vehicle speed sensor 13 detects that the vehicle speed is equal to or higher than a predetermined speed, and the controller 12 sends the electromagnetic valve 11 to the controller of the electromagnetic valve 11 in response to a signal output from the vehicle speed sensor 13. A control signal for switching to the 2 switching position B2 is output. Thereby, the supply of the switching signal pressure guided through the pilot passage 10 to the control port 7 b of the on-off valve 7 is blocked, and the control port 7 b of the on-off valve 7 communicates with the tank 4 via the electromagnetic valve 11. Therefore, the force due to the differential pressure between the pressure of the control port 7a and the pressure of the control port 7b becomes larger than the spring force, the on-off valve 7 is switched to the open position A2, and the bottom chamber 2a of the boom cylinder 2 is turned on the on-off valve 7 To the accumulator 5 via the open position A2. Thereby, pressure fluctuations in the bottom chamber 2a of the boom cylinder 2 during traveling are absorbed by the accumulator 5, and a boom (not shown) driven by the arm cylinder 2, other work tools connected to the boom, and vibration of the vehicle body are caused. It can be suppressed.

  Further, when the on-off valve 7 is switched from the closed position A1 to the open position A2 in accordance with the transition from the working state to the traveling state, the pressure oil in the bottom chamber 2a of the boom cylinder 2 that is at high pressure is reduced to the low pressure side. The pressure reducing valve 14 functions so as to prevent the operation of the boom cylinder 2 by instantaneously flowing into the accumulator 5, that is, the lowering of the boom (not shown). That is, the pressure in the accumulator 5 is maintained at a predetermined pressure by the pressure reducing valve 14, that is, a pressure that is not significantly lower than the pressure in the bottom chamber 2 a of the boom cylinder 2. Thereby, at the time of transition from the working state to the traveling state, excessive inflow of pressure oil from the bottom chamber 2a of the boom cylinder 2 to the accumulator 5 is suppressed, and the operation of the boom cylinder 2 at the time of transition is suppressed.

  As described above, according to the present embodiment, without having a branch passage that branches from the discharge pipe of the main pump 1 or the main pipe communicating with the discharge pipe and is directly connected to the pressure reducing valve 14, According to the switching signal pressure with respect to the on-off valve 7 guided by the pilot passage 10, it is possible to achieve good workability during work and absorption of pressure fluctuations in the bottom chamber 2a of the boom cylinder 2 during travel. The pilot passage 10 described above is built in the valve block 3, one end is connected to the control line 9 a that connects the boom cylinder 2 and the accumulator 5, and the other end is connected to the control port 7 b of the on-off valve 7. Can be set to a very short passage. Thereby, the apparatus structure can be simplified, the manufacturing cost can be reduced, and the entire piping design is facilitated.

1 is a hydraulic circuit diagram showing an embodiment of a work vehicle control device according to the present invention.

Explanation of symbols

1 Main pump 2 Boom cylinder (hydraulic cylinder)
2a bottom chamber 2b rod chamber 3 boom direction control valve 4 tank 5 accumulator 6 valve block 7 on-off valve 7a control port 7b control port 7c passage 8 pilot passage 9a control conduit 9b control conduit 10 pilot passage (switching means)
11 Solenoid valve (switching means)
12 Controller 13 Vehicle speed sensor 14 Pressure reducing valve 15 Check valve 16 Restriction (resistance element)
17 Flow path A1 Closed position A2 Open position B1 First switching position B2 Second switching position C1 Switching position C2 Switching position

Claims (7)

A hydraulic cylinder, an accumulator connected to the hydraulic cylinder, and disposed between the hydraulic cylinder and the accumulator, the hydraulic cylinder communicates with the accumulator in an open position, and the hydraulic cylinder is shut off from the accumulator in a closed position. Work vehicle control comprising: an on-off valve, switching means for switching the on-off valve, a pressure reducing valve for maintaining the pressure in the accumulator at a predetermined pressure, and a check valve for preventing backflow of pressure oil from the accumulator side In the device
The work vehicle control device characterized in that the switching means includes a pilot passage for guiding the pressure of the hydraulic cylinder as a switching signal pressure of the on-off valve without interposing the pressure reducing valve. In the invention of claim 1,
The switching means is interposed in the pilot passage, and supplies the switching signal pressure guided to the pilot passage to the control port of the on-off valve, and the control of the on-off valve of the switching signal pressure. A work vehicle control device comprising a solenoid valve having a second switching position for blocking supply to a port. In the invention of claim 2,
A work vehicle control device comprising: a vehicle speed sensor that detects whether or not a vehicle speed is equal to or higher than a predetermined speed; and a controller that controls switching of the electromagnetic valve in accordance with a signal output from the vehicle speed sensor. In the invention of claim 1,
The closed position of the on-off valve has a passage communicating with the hydraulic cylinder,
A control device for a work vehicle, comprising a flow path that connects the passage in the closed position of the on-off valve and the pressure reducing valve, and a resistance element is disposed in the flow path. In the invention of claim 4,
A control device for a work vehicle, wherein the check valve is disposed in a portion of the flow path located between the pressure reducing valve and the resistance element. In the invention according to claim 4 or 5,
A control device for a work vehicle, wherein the resistance element comprises a diaphragm. In the invention according to any one of claims 1 to 6,
The work vehicle control device, wherein the hydraulic cylinder is a boom cylinder, and the switching signal pressure is a bottom pressure of the boom cylinder.

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