WO2005035883A1

WO2005035883A1 - Travel vibration suppressing device for working vehicle

Info

Publication number: WO2005035883A1
Application number: PCT/JP2004/014827
Authority: WO
Inventors: Norihide Mizoguchi; Hisashi Asada; Daisuke Kozuka; Kazunori Ikei; Shuuji Hori
Original assignee: Komatsu Ltd.
Priority date: 2003-10-10
Filing date: 2004-10-07
Publication date: 2005-04-21
Also published as: CN1867737B; CN1867737A; JPWO2005035883A1; KR100820447B1; DE112004001897T5; SE532253C2; KR20060094961A; SE0600799L; JP4456078B2; DE112004001897B4

Abstract

A travel vibration suppressing device (20) has a directional control valve (30) for a bucket, a directional control valve (29) for a boom, a ride control valve (31), and a boom speed increasing valve (33) that are integrally layered on each other with internal piping. A bottom chamber (11a) of a boom cylinder (11) and an accumulator (27) are communicated or shut off from each other by the ride control valve (31). The boom speed increasing valve (33) is capable of feeding a discharge pressure from a hydraulic pump (21) to the bottom chamber (11a) or a head chamber (11b), and is also capable of connecting the bottom chamber (11a) or the head chamber (11b) to a tank (23).

Description

Specification

Work vehicle running vibration suppression device

Technical field

The present invention relates to a traveling vibration suppressing device for a working vehicle, and in particular, in a working vehicle equipped with a working device, suppresses a pressure pulsation in the working device during traveling with an accumulator to reduce vibration of a vehicle body. The present invention relates to a traveling vibration suppressing device.

Background art

[0002] Conventionally, a wheel loader, which is an example of a work vehicle, includes a boom attached to a vehicle body so as to be able to move up and down, a work member such as a packet rotatably attached to the boom, a boom and a work member. A working device, such as a boom cylinder and a bucket cylinder, for actuating the brakes is attached to the vehicle body. Excavation of earth and sand by operating the boom and work members

, Transport, loading, etc.

[0003] In a wheel loader, for example, a dynamic damper for a work vehicle disclosed in Patent Document 1 is disclosed in Patent Document 1 in order to suppress pressure pulsation and to reduce vehicle body vibration in order to improve riding comfort and prevent load spillage in a work device during traveling. Has been proposed. As shown in Fig. 14, the dynamic damper of the work vehicle is configured as follows.

[0004] Elevating cylinder (hereinafter referred to as boom cylinder 112) force The hydraulic oil from hydraulic pump 117 is received by control valve 119 to expand and contract, thereby raising and lowering the boom. The control valve 119 is connected to a head-side oil chamber 126 of the boom cylinder 112 via a pipe 127, and is connected to a bottom-side oil chamber 128 via a pipe 129.

[0005] The pipe 127 and the pipe 129 are connected to a branch pipe 130 and a branch pipe 131, respectively, which branch off in the middle of the pipe. The branch pipe 130 is connected to the oil tank 116 via the switching valve 133. The branch pipe 131 is connected to an accumulator 162 via a switching valve 133 and a variable throttle device 161. The switching valve 133 is constituted by an electromagnetic valve, and is urged by the spring to switch to the shut-off position when not energized, and to switch to the connection position when energized.

[0006] The variable throttle device 161 is a throttle device capable of adjusting the throttle opening in a plurality of stages, and includes a plurality of throttles 164, 165, a switching valve 166 for selecting an aperture, and a force. Switching valve 166 Is constituted by an electromagnetic valve, and when not energized, is urged by a spring to switch to a position for selecting a throttle 164 having a large throttle opening. When energized, switch to the position to select the aperture 165 with a small aperture. The switching valve 133 and the switching valve 166 are controlled by the controller 153.

[0007] A pressure sensor 149 connected to the pipe 129 detects the pressure of the bottom oil chamber 128. The controller 153 excites the coil of the switching valve 133 when the pressure in the bottom oil chamber 128 detected by the pressure sensor 149 is in the range between the minimum allowable pressure of the accumulator and the maximum allowable pressure. To switch to the connection position. When the pressure detected by the pressure sensor 149 is equal to or higher than the set pressure, the controller 153 selects the position of the switching valve 166 according to the pressure detected by the pressure sensor 149.

[0008] The set pressure is set as follows. That is, an appropriate set mass between the minimum mass of the working device to be mounted and the maximum mass of the working device including the load is assumed. For example, set the mass of 1Z2 which is the sum of the minimum mass and the maximum mass as the set mass. Assuming that the mass of the working device is the assumed constant mass, when the control valve 119 is at the neutral position, the pressure in the bottom oil chamber 128 of the boom cylinder 112 at this time is defined as the set pressure.

[0009] In the above configuration, the control valve 119 is set to the neutral position, and the switching switch 155 is turned on to operate the dynamic damper. This allows pitching of the vehicle body when the wheel loader travels,

RU

[0010] The wheel loader is run with the dynamic damper operated. At this time, the work equipment vibrates in response to road surface conditions, acceleration and deceleration of the vehicle, and the like, and the boom also attempts to swing vertically. Therefore, a pressure fluctuation occurs in the bottom oil chamber 128 of the boom cylinder 112 that holds the boom.

At this time, the pressure in the bottom oil chamber 128 is detected by the pressure sensor 149. When the detected pressure force is equal to or higher than the minimum allowable pressure of the accumulator 162 and equal to or lower than the maximum allowable pressure, the controller 153 switches the switching valve 133 to the connection position.

When the mass of the working device is smaller than the above-mentioned set mass and the pressure in the bottom oil chamber 128 is lower than the set pressure, the switching of the switching valve 166 causes the bottom oil chamber 128 and the accumulator to accumulate. The connection with the radiator 162 is made via a throttle 164 having a large throttle opening. When the mass of the work equipment is equal to or greater than the set mass and the pressure in the bottom oil chamber 128 is equal to or greater than the set pressure, the switching valve 166 is switched to have a small throttle opening with the bottom oil chamber 128 and the accumulator 162. The connection is made via the aperture 165 that has been set.

[0013] Accordingly, even if the mass of the working device changes and the vibration characteristics change, vibration of the vehicle body such as pitching and bouncing can be effectively suppressed by the operation of the dynamic damper.

Patent Document 1: Japanese Patent Application Laid-Open No. 2001-200804

Disclosure of the invention

Problems to be solved by the invention

[0014] However, in the dynamic damper of the work vehicle disclosed in Patent Document 1, the force required to use two solenoid valves, a switching valve 133 for selecting a dynamic damper and a switching valve 166 for selecting a throttle, is required. I got it. Since the switching valve 133 is separately installed at a position separated from the control valve 119, the branching pipes 130 and 131 branched from the pipes 127 and 129 connecting the control valve 119 and the boom cylinder 112 are also provided. I need.

[0015] For this reason, as the number of pipes increases, the area of the pipes increases, and it becomes difficult to secure a space for the pipes. In addition, since two solenoid valves and a plurality of throttles are required as switching valves, the number of parts increases and the price rises.

When the switching switch 155 is turned on during traveling of the wheel loader, the bottom oil chamber 128 of the boom cylinder 112 is connected to the accumulator 162 via the switching valve 133 and the switching valve 166. At this time, if the sum of the mass of the working device and the mass of the load is largely apart from the mass force assumed when defining the set pressure of the accumulator 162, the dynamic damper can be activated effectively. What,

[0017] For example, when the pressure of the accumulator 162 is higher than the pressure in the bottom oil chamber 128, the pressure of the accumulator 162 on the high pressure side is suddenly supplied to the bottom oil chamber 128 on the low pressure side. Therefore, the boom cylinder 112 extends, and the boom rises rapidly.

When the pressure of the accumulator 162 is lower than the pressure of the bottom oil chamber 128, Is rapidly supplied to the accumulator 162 on the low pressure side. At this time, the boom cylinder 112 contracts rapidly, and the boom descends rapidly. Thus, an unexpected boom behavior occurs for the operator.

Further, when the work vehicle rides on a stone or the like while traveling, the instantaneous flow rate flowing out of the boom cylinder 112 sharply increases. In order to flow the large instantaneous flow generated at this time, it is required to provide a pressure device having a low pressure loss in the traveling vibration suppressing device. Furthermore, the traveling vibration suppression device is required to have good response characteristics in order to reduce the impact on the working device when vibration occurs.

[0020] Furthermore, the switching valve has an opening area that can sufficiently cope with a large pressure fluctuation width in the bottom oil chamber caused by the loaded mass of the working member, or the setting of the actuator. There is a need for a device that can easily change the pressure over a wide range, etc., for a traveling vibration suppression device.

In particular, the following configuration is demanded for a traveling vibration suppression device in a wheel loader or the like. For example, when the boom is pushed up, the accumulator absorbs pressurized oil from the bottom side oil chamber quickly with good responsiveness, and suppresses the rise of the boom. There is a demand for a configuration capable of suppressing the descent of the boom by slowly supplying the pressure oil to the side oil chamber and suppressing the vibration of the boom in a short time.

The present invention has been made in view of the above-mentioned problems, and includes a directional control valve for controlling an actuator of a working device mounted on a work vehicle, and a ride control valve for connecting an accumulator and an actuator. It is an object of the present invention to provide a traveling vibration suppressing device which has a simple configuration, suppresses pressure pulsation in a responsive actuator having good responsiveness, and can reduce vibration of a vehicle body.

Means for solving the problem

[0023] In order to achieve the above object, according to the present invention, as described in claim 1, a hydraulic pump and at least one or more actuators operated by hydraulic oil discharged from the hydraulic pump are provided. Connected to one pressure chamber of at least one of the actuators

An accumulator for absorbing pressure pulsations in the pressure chamber, and the actuator from the hydraulic pump. In a traveling vibration suppressing device for a working vehicle, comprising: a directional control valve for controlling pressure oil supplied to a eater, and a ride control valve for controlling communication and shutoff between the accumulator and the pressure chamber, the ride control valve includes: The most main feature is that the directional control valve is laminated and arranged by internal piping.

[0024] Further, according to the present invention, the communication opening area of the ride control valve is controlled using a pressure sensor for detecting a load pressure of the actuator and a traveling state detection sensor for detecting a traveling state of the work vehicle. Using a pressure sensor to detect pressure, setting conditions for communication between the accumulator and the actuator, controlling the upper limit opening area that can be opened as the communication opening area of the ride control valve, controlling the variable throttle The main features of the present invention are that the pressure of the actuator and the accumulator are made equal by using the same, and that the speed-increasing valve is laminated on the ride control valve or the directional control valve.

The invention's effect

[0025] In the present invention, the directional control valve and the ride control valve for the actuator are stacked and arranged by internal piping. Thus, the oil passage connecting both valves can be communicated with each other at the mating surface of the direction control valve and the ride control valve, and the vibration suppression device for traveling can be made compact. As the external piping between the actuator and the accumulator, the piping connecting the directional control valve and the actuator and the piping connecting the ride control valve and the accumulator are used.

[0026] For this reason, the number of pipes provided for external pipes can be reduced, and the length of pipes used for external pipes can be shortened. As the number of external pipes is reduced, the space required for external pipes can be reduced by reducing the length of the pipes. In addition, the work of installing the external piping becomes easy.

[0027] The pressure loss in the pipe can be reduced by the internal pipe, and the flow force can be secured to a large diameter for the instantaneous flow rate, so that the responsiveness of the ride control valve is improved. In addition, an excessive impact pressure acting on the accumulator is reduced, and the durability of the accumulator is improved.

[0028] For this reason, vibrations such as pitching and bouncing of the vehicle body at the time of occurrence of vibrations are effective. Can be effectively suppressed. In addition, the ride control valve can be configured so that one spool can supply the pressurized oil to the accumulator and shut off the communication between the accumulator and the actuator. Since the traveling vibration suppressing device can be configured with a simple configuration, the number of components for constituting the traveling vibration suppressing device can be reduced, and the traveling vibration suppressing device can be configured at low cost.

[0029] In the present invention, as described in claim 2, the communication opening area of the ride control valve can be controlled based on the pressure sensor and the detection signal of Z or the running state detection sensor force. For example, when the boom mounted on the work vehicle is raised by the vibration generated during traveling of the work vehicle, control is performed to widen the communication opening area, and the pressurized oil, which has become high pressure from the bottom chamber of the actuator, is quickly released by the accumulator. Can be absorbed. Thereby, a rapid rise of the boom can be suppressed.

Further, when the boom is lowered by vibration generated during traveling of the work vehicle, control is performed to reduce the communication opening area, and the pressure oil supplied to the accumulator force actuator is reduced and supplied. Can be. This allows the boom to be lowered slowly. In this manner, pressure pulsation of the actuator due to vibration generated during traveling of the work vehicle can be suppressed in a short time.

In the present invention, as described in claim 3, when the pressure in the accumulator is higher than the load pressure of the actuator, the accumulator and the actuator are connected in the same state. Instead, the accumulator and the actuator can be connected after the pressure in the accumulator is reduced to the load pressure of the actuator.

[0032] As a result, when the accumulator is connected to the actuator, for example, the pressure in the accumulator is higher than the load pressure of the accumulator, and the boom suddenly rises due to the pressure of the accumulator. Can be prevented.

[0033] In the present invention, as described in claim 4, in controlling the communication opening area of the ride control valve up to the upper limit opening area, the value of the upper limit opening area is also controlled. can do. Regarding the opening area of the upper limit, as described in claims 5 and 6, according to the load pressure of the actuator and Z or the traveling speed of the work vehicle, the upper limit of the upper limit Control the value of the opening area You can do it.

[0034] For example, when the load pressure of the actuator caused by the loaded mass of the working member is high, or when the traveling speed of the work vehicle is high, the upper limit opening area that can be opened as the communication opening area can be reduced. This prevents an excessive impact pressure from acting on the accumulator and improves the durability of the accumulator.

[0035] For example, when the load pressure of the actuator caused by the loaded mass of the work member is low or when the traveling speed of the work vehicle is low, the upper limit opening area that can be opened as the communication opening area can be increased. Thereby, the responsiveness of the accumulator to the pressure pulsation of the actuator can be improved.

[0036] As described above, it is possible to obtain a traveling vibration suppressing device adapted to the load pressure and Z of the actuator or the traveling state of the work vehicle. In addition, the actuator does not expand and contract unexpectedly under the pressure of the accumulator force as in the related art, and the drivability of the work vehicle is improved.

In the present invention, as described in claim 7, the pressure between the actuator and the accumulator can be equalized by the variable throttle provided in the ride control valve. Thereby, even if the fluctuation range of the load pressure of the actuator caused by the load mass of the working member greatly changes, the pressure of the accumulator can be easily adjusted over a wide range so that the pressure corresponds to the load pressure of the actuator. be able to.

[0038] In the present invention, as described in claim 8, a speed-increasing valve can be arranged adjacent to the directional control valve or the ride control valve. The supply flow rate and discharge flow rate to the actuator can also be made to flow from the speed-up valves arranged in layers. Since the flow rate of the pressure oil to be supplied to and discharged from the actuator can be partially flowed by the speed increasing valve, it is possible to mount the traveling vibration suppressing device of the present invention even on a medium-sized or large-sized work vehicle. As a result, an excellent vibration suppressing effect can be achieved.

Brief Description of Drawings

FIG. 1 is a schematic side view of a wheel loader using a traveling vibration suppression device according to the present invention.

FIG. 2 is a configuration diagram of a traveling vibration suppression device. FIG. 3 is a pressure circuit of the traveling vibration suppressing device. (Example 1)

FIG. 4 is a circuit diagram of a ride control valve and a control unit. (Example 1)

FIG. 5 is a view for explaining a stroke and an opening area of the ride control valve. (Example 1)

FIG. 6 is a time chart of the ride control valve. (Example 1)

FIG. 7 is a circuit diagram of a first ride control valve and a control unit. (Example 2)

FIG. 8 is a diagram illustrating a stroke and an opening area of a first ride control valve. (Example 2)

FIG. 9 is a time chart of the first ride control valve. (Example 2)

FIG. 10 is a circuit diagram of a second ride control valve and a control unit. (Example 3)

FIG. 11 is a diagram illustrating a stroke and an opening area of a second ride control valve. (Example 3)

FIG. 12 is a time chart of the second ride control valve. (Example 3)

FIG. 13 is a circuit diagram of a third ride control valve and a control unit. (Example 4)

FIG. 14 is a diagram showing a hydraulic circuit of a working device. (Conventional example)

Explanation of symbols

1 Hoi Norrero-da

2 Vehicle body

3 Working equipment

10 boom

11 Boom cylinder (: Actuator for boom)

13 bucket

15 buckets

20, 20A ゝ 20B ゝ 20C Travel vibration suppression device

21 Hydraulic pump

23 tank

25 directional control valve

27 Accumulation 29 Boom directional control valve (Boom directional control valve)

30 Directional control valve for packet

31, 31A, 31B ride control valve

33 Boom speed increase valve

56 Ride valve control

56a Control room

56b Proportional control valve

57, 57a, 57b, 57c Controller

61 Piping for oil supply

62 Return piping

63 Oil passage for tank

67 Pump piping

73 Piping

81 Boom pressure sensor

82 Accumulator pressure sensor

84 Running state detection sensor

86 Variable aperture

88 Variable throttle valve

90 1st proportional control valve

W1— W3 mating surface

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of a traveling vibration suppression device according to the present invention will be described below with reference to the drawings. A wheel loader will be described as an example of a work vehicle equipped with the traveling vibration suppression device, but a work vehicle on which the traveling vibration suppression device according to the present invention can be mounted is not limited to a wheel loader. Absent. As long as pressure pulsation is generated in the actuator of the working device during traveling of the work vehicle, the traveling vibration suppressing device according to the present invention can be mounted on the work vehicle as a device for suppressing pressure pulsation. Therefore, the traveling vibration suppressing device is limited to the configuration described below. Instead, various changes are possible.

In FIG. 1, the wheel loader 1 includes a vehicle body 2 and a working device 3 attached to a front portion of the vehicle body 2. The vehicle body 2 includes a vehicle body 7 including a front frame 5, a rear frame 6, and the like, and a cabin 8 and the like.

The working device 3 is interposed between a pair of left and right booms 10 pivotally supported by a pivot shaft 9 of the front frame 5 so as to be able to move up and down, and between the front frame 5 and each of the booms 10. A pair of boom cylinders 11 for raising and lowering the boom, a packet 13 rotatably supported by the front ends of a pair of booms 10 respectively, and a packet 13 interposed between the front frame 5 and the packet 13 to rotate the packet 13 It comprises a moving bucket cylinder 15 and the like. The traveling vibration suppressing device 20 is provided at a portion surrounded by a dotted line on the front frame 5 side.

Example 1

As shown in FIG. 2 as a configuration diagram of the traveling vibration suppressing device 20, a directional control valve body 30 ′ for packet (hereinafter, referred to as a packet valve body 30 ′) and a directional control valve body 29 ′ for boom (hereinafter, referred to as “packet valve body 30”). , A boom valve body 29), a ride control valve body 31, (hereinafter referred to as a ride valve body 31 ') and a boom speed increasing valve body 33' (hereinafter referred to as a speed increasing valve body 33 '). The inner pipes are stacked and arranged to form one block body 25. The traveling vibration suppressing device 20 will be described below using the traveling vibration suppressing device 20 in which the above-described four valve bodies are configured as one block body 25.

The traveling vibration suppressing device 20 in which a packet direction control valve 30 (hereinafter, referred to as a packet valve 30) and a boom speed-increasing valve 33 (hereinafter, referred to as a speed-increasing valve 33) are stacked will be described below. However, the stacked arrangement of the packet valve 30 and the speed increasing valve 33 is not always necessary as the traveling vibration suppressing device 20. At least the boom directional control valve 29 (hereinafter referred to as the boom valve 29) and the ride control valve 31 (hereinafter referred to as the ride valve 31) are stacked and arranged, and the configuration is necessary for the traveling vibration suppressing device 20. It has a simple configuration.

As shown in FIG. 2, the hydraulic pump 21 supplies oil sucked from the tank 23 to the block body 25 as discharge pressure oil. The packet valve 30 (see FIG. 3) in the packet valve body 30 ′ is switched by a pilot pressure (not shown), and supplies the pressure oil discharged from the hydraulic pump 21 to the bucket cylinder 15 to control the operation of the bucket cylinder 15. I do. Also, the boom in the boom valve body 29 ' The boom cylinder 29 (see FIG. 3) is switched by a pilot pressure (not shown), and controls the operation of the boom cylinder 11 by supplying the discharge pressure oil from the hydraulic pump 21 to the boom cylinder 11.

The ride valve 31 (see FIG. 3) in the ride valve body 31 ′ is switched by a pilot pressure (not shown) to connect and disconnect the boom cylinder 11 and the accumulator 27. This allows the accumulator 27 to suppress the pressure pulsation of the boom cylinder 11 generated by the vibration of the vehicle body 7 during running.

The speed increasing valve 33 (see FIG. 3) in the speed increasing valve body 33 ′ is switched by a pilot pressure (not shown) to increase the diameter of the flow path connecting the boom cylinder 11 and the accumulator 27. In addition, the diameter of the flow path connecting the boom cylinder 11 and the tank 23 can be increased.

[0049] The pressure circuit of the traveling vibration suppression device 20 will be described with reference to FIG. The traveling vibration suppression device 20 has a configuration in which a boom valve 29, a packet valve 30, a ride valve 31, and a speed-increasing valve 33 are laminated on one another. In FIG. 3, the tank 23 is shown in the traveling vibration suppression device 20, but this is to make the pressure circuit easier to see by omitting the connection pipe to the tank 23. Actually, it is connected to a tank 23 provided outside via a pipe (not shown).

The packet valve body 30 ′ and the boom valve body 29 ′, the boom valve body 29 ′ and the ride valve body 31, and the ride valve body 31 and the speed-up valve body 33 ′ are arranged adjacent to each other. Te! The pipes in each valve body are connected to each other at the mating surface W1-W3 between the adjacent bodies.

[0051] The block body 25 is formed as a closed center, and is formed as a parallel valve in which the boom valve 29 and the bucket valve 30 are connected in parallel to the hydraulic pump 21 by a pump pipe 35. Thus, the traveling vibration suppressing device 20 in which the oil passage is formed by the internal piping is configured.

[0052] The packet valve 30 is formed in the packet valve body 30 '. The bottom pipe 39a connects the bottom chamber 15a of the bucket cylinder 15 to the port 30a of the packet valve 30, and the head pipe 39 connects the head chamber 15b of the bucket cylinder 15 to the boat 30b. Port 30c is connected to the discharge port of hydraulic pump 21 via piping 35, and port 30d is connected to tank 23 Connected.

[0053] The packet valve 30 is provided at three positions: a tilt position (H) for extending the piston of the bucket cylinder 15, a dump position (L) for reducing the piston, and a neutral position (N) for maintaining the piston in the expanded and contracted state. Can be switched. When the pilot valve is operated to switch the operation position of the packet valve 30 to the tilt position (H), the pressure oil discharged from the hydraulic pump 21 is supplied to the bucket cylinder 15 via the port 30c, the port 30a and the bottom pipe 39a. The pressure oil supplied to the bottom chamber 15a and discharged from the head chamber 15b is discharged to the tank 23 via the head pipe 39b, the port 30b, and the port 30d. Thereby, the piston of the bucket cylinder 15 can be extended.

When the operating position of the packet valve 30 is switched to the dump position (L), the pressure oil discharged from the hydraulic pump 21 is supplied to the head chamber 15b via the port 30c, the port 30b and the head piping 39b, The pressure oil in the bottom chamber 15a is discharged to the tank 23 via the bottom pipe 39a, the port 30a and the port 30d. Thereby, the piston can be reduced. When the packet valve 30 is at the neutral position (N), the connection between the packet valve 30 and the bucket cylinder 15 is cut off, and the piston can be maintained in the expanded and contracted state.

[0055] A boom valve 29 is formed in the boom valve body 29 '. The bottom chamber 11a of the boom cylinder 11 and the port 29a of the boom valve 29 are connected via the bottom pipe 37a, and the head chamber lib and the port 29b are connected via the head pipe 37b. The port 29c is connected to the discharge port of the hydraulic pump 21 via a pipe 35, and the port 30d is connected to the tank 23.

[0056] At both ends of the boom valve 29, pilot chambers 49a and 49b that receive pilot pressure via a pressure proportional pressure reducing valve (not shown) operated by an operation lever or the like are formed. In the pilot chambers 49a and 49b, the pilot chambers 49a and 49b on one side receive the pilot pressure via a pressure proportional pressure reducing valve (not shown), and the pressure oil in the pilot chambers 49b and 49a on the other side receives a pressure proportional reducing valve (not shown). And then returned to the tank 23.

[0057] The boom valve 29 can be switched to four positions: a floating position (F), a lowered position (L), a neutral position (N), and a raised position (H). Switching to the four positions can be performed by a panel acting on both ends of the boom valve 29 and a pilot pressure acting on the pilot chambers 49a and 49b. [0058] At the raised position (H), the pressure oil discharged from the hydraulic pump 21 is supplied to the bottom chamber 11a of the boom cylinder 11 via the port 29c, the port 29a, and the bottom pipe 37a, and the pressure oil in the head chamber l ib is supplied. Is discharged to the tank 23 through the head pipe 37b and the ports 29b and 29d. Thereby, the piston of the boom cylinder 11 is extended, and the boom 10 is raised.

[0059] At the neutral position (N), the connection between the boom valve 29 and the boom cylinder 11 is cut off, and the piston in the boom cylinder 11 can be maintained in the expanded and contracted state.

At the lowered position (L), the pressure oil discharged from the hydraulic pump 21 is supplied to the head chamber l ib via the port 29c, the port 29b and the head pipe 37b, and the pressure oil in the bottom chamber 11a is supplied to the bottom pipe 37a and the port It is discharged to tank 23 via 29a and 29d. Thereby, the piston of the boom cylinder 11 contracts and lowers the boom 10.

At the floating position (F), the port 29a, the port 29b, and the port 29d are all connected, and the bottom chamber 1la and the head chamber lib communicate with each other while being connected to the tank 23. This allows the boom cylinder 11 to freely expand and contract in response to external force, and causes the boom 10 to float.

The ride valve body 31 ′ is formed with a ride valve 31, a proportional control valve 56 b as a ride valve control unit 56, and a charge reducing valve 66. The ride valve 31 has a panel energized at one end, and a slot chamber 56a formed at the other end for receiving pilot pressure from the proportional control valve 56b. The proportional control valve 56b and the pilot chamber 56a constitute a ride valve control unit 56.

The port 31 a of the ride valve 31 is connected to the accumulator 27 via the accumulator pipe 40. The port 3 lb is connected from the bottom pipe 37a to the bottom chamber 11a via the pipe 45a and the pipe 73.

[0063] The port 31c is connected to the head chamber l ib from the head piping 37b via the piping 45b. The port 31d is connected to the discharge port of the hydraulic pump 21 via a pipe 35 and a pressure reducing valve 66 for charging, and the port 31e is connected to the tank 23.

[0064] The port 31d can be connected to the accumulator 27 via the port 31a and the accumulator pipe 40 when the ride valve 31 is not operated.

The ride valve 31 connects the operating position (A) of the traveling vibration suppression device 20 that connects the accumulator 27 to the bottom chamber 11a of the boom cylinder 11, and connects the hydraulic pump 21 and the accumulator 27. It can be switched between two positions, that is, the inoperative position (B) of the traveling vibration suppression device 20. The switching of the ride valve 31 is performed by controlling the proportional control valve 56b by a control signal from a controller 57 (not shown) (see FIG. 4).

The proportional control valve 56b is connected to the control pump 59. When the proportional control valve 56b operates upon receiving a signal from the controller 57, the pressure oil discharged from the control pump 59 is supplied as pilot pressure to the pilot chamber 56a to switch the ride valve 31. The charge pressure reducing valve 66 sets the pressure of the accumulator 27 to the set pressure set by the charge pressure reducing valve 66 when the ride valve 31 is not operated.

When the ride valve 31 is in the non-operating position (B) and the charging pressure reducing valve 66 is operating, the pressure oil discharged from the hydraulic pump 21 can be reduced and accumulated in the accumulator 27. When the ride valve 31 is in the operating position (A), the accumulator 27 is connected to the bottom chamber 11a, and the head chamber lib is connected to the tank 23 via the port 31c and the port 3le.

When the ride valve 31 is at the operating position (A), the accumulator 27 can absorb and attenuate the pressure pulsation generated in the bottom chamber 11a of the boom cylinder 11 when the wheel loader 1 travels. Further, oil can be supplied and discharged between the head chamber l ib and the tank 23.

[0069] The speed-up valve body 33 'is formed with a speed-up valve 33. The port 33a of the speed increasing valve 33 is connected to a bottom pipe 37a through a pipe 73 and an external oil supply pipe 61 by a boom speed increasing pipe 41. The port 33b is connected to a discharge port of the hydraulic pump 21 via a pipe 35, and the port 33c is connected to the tank 23.

[0070] The speed increasing valve 33 switches between three positions: a lowering position (Ld) for increasing the contraction of the boom cylinder 11, a neutral position (N), and an raising position (Hu) for increasing the extension of the boom cylinder 11. Can be done. Switching to the three positions can be performed by receiving pilot pressure in pilot chambers 75a and 75b formed at both ends of the speed increasing valve 33.

[0071] Panels are provided in each of the pilot chambers 75a and 75b, and the speed increasing valve 33 is held at a neutral position (N). The same pilot pressure acts on the pilot chamber 75a and the pilot chamber 49a of the boom valve 29 via the pipe piping 77a. The same pilot pressure acts on the pilot chamber 75b and the pilot chamber 49b of the boom valve 29 via the pilot pipe 77b.

[0072] The pilot room 75a and the pilot room 49a or the pilot room 75b and the pilot room 49b When pilot pressure acts on one pilot chamber, the other pilot chamber is connected to tank 23. Thus, the speed increasing valve 33 can be switched in synchronization with the boom valve 29.

[0073] The speed-up valve 33 is switched to the lowered position (Ld) because the boom valve 29 is switched to the lowered position (L) or the floating position (F) by receiving the pilot pressure and receives the same pilot pressure. This is when the speed increasing valve 33 is switched to the lowered position (Ld). At this time, the discharge pressure oil from the hydraulic pump 21 is supplied to the head chamber lib through the boom valve 29. The pressurized oil in the bottom chamber 11a is discharged from the boom valve 29 to the tank 23 through the bottom pipes 37'a and 37a, and the speed is increased through the pipe 41 through the pipes 61 and 73 branched from the bottom pipe 37a. It is discharged from the valve 33 to the tank 23.

When the boom valve 29 is at the neutral position (N) and the speed increasing valve 33 is also at the neutral position (N), the connection between the port 33b and the port 33a is cut off. When the boom valve 29 receives the pilot pressure and switches to the raising position (H), and receives the same pilot pressure, the speed increasing valve 33 switches to the raising position (Hu), the discharge pressure oil from the hydraulic pump 21 becomes It is supplied to the bottom chamber 11a via the boom valve 29 and the speed increasing valve 22. The pressure oil in the head chamber l ib is discharged from the boom valve 29 to the tank 23.

In the above description, an example has been described in which the packet valve 30, the boom valve 29, the ride valve 31, and the speed increasing valve 33 are controlled by the pilot pressure. However, the control of each of the valves is controlled by the pilot pressure. It is also possible to control with an electromagnetic solenoid which is not limited to this. Further, the pilot chamber or the electromagnetic solenoid of each valve can be removably attached by disposing outside the respective valve block. This makes it possible to reduce the size of each valve block and improve the ease of maintenance of the pilot chamber or the electromagnetic solenoid.

[0076] The piping 35 is increased in speed with the mating surface Wl of the packet valve body 30 'and the boom valve body 29', the mating surface W2 of the boom valve body 29 and the ride valve body 31 ', and the ride valve body 31'. Pipes are respectively passed through the mating surfaces W3 with the valve bodies 33 '. Also, the pipe 45b is piped through the mating surface W2 of the boom valve body 29 and the ride valve body 31,! The piping 73 and the pilot piping 77b have a mating surface W2 between the boom valve body 29 and the ride valve body 31, and a mating surface W3 between the ride valve body 31 'and the booster valve body 33', respectively. Each pipe is penetrated. Oil supply piping 61 is provided by external piping

[0077] The pilot pipes 77a and 77b can be configured as internal pipes or external pipes.

[0078] As a configuration of the traveling vibration suppressing device 20, the configuration in which the speed increasing valves 33 are stacked is described, but the speed increasing valve 33 is not necessarily provided. Can be added for quick operation. The speed-up valve 33 can supply pressurized oil with reduced resistance even if the load capacity of the bucket increases and the diameter of the boom cylinder 11 that operates the bucket increases.

Next, the operation of the traveling vibration suppression device 20 will be described. First, the operation of the ride valve 31 will be described with reference to FIGS. 4, 5, and 6, and then the vibration suppression of the traveling vibration suppression device 20 will be described for the wheel loader 1. FIG.

FIG. 4 omits the configurations of the boom valve 29 and the speed increasing valve 33 in order to explain the configuration of the ride valve 31. As shown in FIG. 4, when the control signal is not output from the controller 57 and the ride valve 31 is not operated, the proportional control valve 56b connects the pilot chamber 56a of the ride valve 31 to the tank 23 and the pilot chamber 56a is connected to the pilot chamber 56a. The applied pilot pressure is low. The ride valve 31 is located at the inoperative position (B) of the traveling vibration suppressing device 20 by the urging force of the panel 55a.

At this time, the ride valve 31 supplies the discharge pressure oil of the pressure pump 21 reduced to the charge pressure set by the charge pressure reducing valve 66 to the accumulator 27 and accumulates the pressure as the pressure of the accumulator 27.

At the start of the operation of the ride valve 31, as shown in FIG. 6A, the control current output from the controller 57 to the proportional control valve 56b is sequentially increased from time T1. The proportional control valve 56b receives the control signal from the controller 57, connects the pilot chamber 56a of the ride valve 31 to the control pump 59, and gradually increases the pilot pressure supplied to the pilot chamber 56a.

[0083] Thereby, as shown in Fig. 6 (b), the spool of the ride valve 31 increases the stroke amount against the urging force of the panel 55a. As a result, the ride valve 31 switches from the non-operation position (B) to the operation position (A). At this time, as shown in FIG. 6 (c), the opening area Sa connecting the port 31d and the port 31a is reduced by the area force of A1 and becomes zero at time T2 (AO). State. After that, the area is kept at zero (AO).

[0084] From time T2 to time T3, as shown in Fig. 6 (d), the opening area Sb that connects the port 3 la and the port 3 lb is increased when the opening area is zero (AO). Then, at time T3, the area becomes the state of A3. Also, at this time, as shown in FIG. 6 (e), the opening area Sc connecting the port 31c and the port 3le has a state force of zero (AO) and the area A4 at time T3 has an area of A4. State.

[0085] The opening area Sc for connecting the head chamber l ib to the tank 23 through communication between the port 31c and the port 31e may be in a fully open state where the area becomes A4 from the time T2. The switching speed of the ride valve 31 can be controlled by the magnitude of the control current output from the controller 57 to the proportional control valve 56b. Therefore, the switching speed of the ride valve 31 can be freely set by controlling the magnitude of the control current.

[0086] Between time T3 and time T4, the proportional control valve 56b is controlled while increasing the control current, but at time T3 before the time T4 is reached, the opening communicating the port 31a with the port 31b is opened. The area Sb has a constant value of A3, and the opening area Sc connecting the ports 31c and 31e has a constant value of A4. No further increase in the opening area is performed. After time T4, the control current output from the controller 57 has a constant value.

FIG. 5 shows the opening area Sa that connects the port 31d and the port 31a, and the opening area that connects the port 31a and the port 31b, where the horizontal axis represents the stroke amount of the spool of the ride valve 31 and the vertical axis represents the opening area. FIG. 9 is a diagram showing the relationship between the opening amount Sb of the ride valve 31 and the opening amount Sc connecting the port 31c and the port 3le with the opening area Sb.

In FIG. 5, when the spool of the ride valve 31 strokes beyond the stroke L1, the opening area Sc connecting the port 31c and the port 31e to connect the head chamber l ib to the tank 23 is equal to the area Is zero (AO), which indicates that the force changes to the state of A4. That is, as described above with reference to FIG. 6, the opening area Sc in which the port 31c and the port 31e communicate with each other to connect the head chamber lib to the tank 23 has a force A at time T2, an area A4, and a fully open state. ing.

In FIG. 5, similarly to FIG. 6 (e), the opening area Sc can be sequentially increased as the stroke amount of the spool of the ride valve 31 increases from the stroke L1. As a result, a predetermined stroke can be obtained for the spool of the ride valve 31, and the upper limit areas A3 and A4 that can be opened as the opening areas Sb and Sc can be reliably obtained. be able to.

[0091] When the traveling of the wheel loader 1 is completed and the operator turns off a switch (not shown) for controlling the proportional control valve 56b, the ride valve 31 returns to the inoperative position (B). At this time, the opening area Sa returns from the state of zero (AO) to the area state of A1, and the opening areas Sb and Sc return to the state of zero (AO) from the state forces of the areas A3 and A4, respectively.

Next, vibration suppression of the wheel loader 1 using the traveling vibration suppression device 20 will be described. For example, when the wheel loader 1 performs excavation work, a switch (not shown) that controls the proportional control valve 56b is turned off. As a result, the controller 57 does not output the control current to the proportional control valve 56b, and the ride valve 31 remains at the non-operation position (B).

[0093] At this time, as shown in FIG. 3, the bottom chamber 11a of the boom cylinder 11 is connected to the port 29a of the boom valve 29 and the port 33a of the speed increasing valve 33, and the head chamber l ib is connected to the port 29b of the boom valve 29. Connected to. In this state, the boom valve 29 is operated by the pilot pressure and the speed increasing valve 33 is operated at the same time, and the discharge pressure oil of the hydraulic pump 21 is supplied to and discharged from the boom cylinder 11 via the boom valve 29 and the speed increasing valve 33. The excavation work can be performed by causing the boom cylinder 11 to expand and contract.

[0094] When the wheel loader 1 travels, the switch is turned ON to suppress the pulsation of the pressure of the boom cylinder 11 due to the undulation of the road surface. As a result, a control current is output from the controller 57 to the proportional control valve 56b, and the ride valve 31 is switched to the operating position (A).

[0095] Thus, the spool of the ride valve 31 can obtain a predetermined amount of stroke by the pilot pressure output from the controlled proportional control valve 56b. According to the stroke amount of the spool of the ride valve 31, the opening area Sb that connects the accumulator 51 and the bottom chamber 1 la of the boom cylinder 11 in the ride valve 31 is changed from the zero (AO) state to the upper limit opening area A3. Increase. Further, in FIG. 6 (e), the opening area Sc connecting the head chamber l ib of the boom cylinder 11 and the tank 23 increases from the state of zero (AO) to the state of the upper limit opening area A4. In FIG. 5, the upper limit of the opening area is A4 directly from the state of zero (AO). [0096] The wheel loader 1 is run with the ride valve 31 switched to the operating position (A). At this time, the boom valve 29 and the speed increasing valve 33 are switched to the neutral position (N). Thereby, both the connection between the boom valve 29 and the ride valve 31 and the bottom chamber 11a of the boom cylinder 11, and the connection between the boom valve 29 and the head chamber l ib can be shut off.

[0097] The wheel loader 1 is run with the ride valve 31 in the operating position (A). The vehicle body 7 vibrates due to the ups and downs of the road surface and the acceleration and deceleration of the wheel loader 1. As a result, the boom 10 supporting the working device 3 tries to rotate in the vertical direction, and the pressure in the oil in the bottom chamber 1 la of the boom cylinder 11 supporting the boom 10 is generated.

[0098] The bottom chamber 11a of the boom cylinder 11 communicates with the accumulator 27 from the ride valve 31 via a pipe 73 branched from the bottom pipe 37a. For this reason, a large amount of fluid can flow instantaneously with little pressure loss. Further, at this time, the head chamber lib communicates with the tank 23 from the port 31c and the port 31e of the ride valve 31 via the head pipe 37b, so that the pressure oil in the head chamber lib can be supplied and discharged. By quickly supplying and discharging pressure oil between the bottom chamber 11a of the boom cylinder 11 and the accumulator 27, pressure pulsation of the boom cylinder 11 can be suppressed promptly.

[0099] In the running vibration suppressing device of the present invention, even when the device is mounted on a medium-sized or large-sized wheel loader 1 that generates large vibration, the pressure of the boom cylinder 11 is maintained between the bottom chamber 11a of the boom cylinder 11 and the accumulator 27. Pulsation can be suppressed quickly.

In the above description, the opening area Sb of the ride valve 31 connecting the accumulator 27 and the bottom chamber 11a of the boom cylinder 11 is the upper limit opening area A3, and the head chamber l ib of the boom cylinder 11 The case where the opening area Sc of the ride valve 31 connecting the tank and the tank 23 is the upper limit opening area A4 has been described. However, the ride valve 31 can be used with an opening area Sb smaller than the opening area A3 without opening the opening area Sb to the upper limit opening area A3.

Example 2

Next, a traveling vibration suppressing device 20A according to a second embodiment of the present invention will be described.

FIG. 7 is a circuit diagram of the ride valve 31A and the control unit, FIG. 8 is a diagram illustrating the relationship between the stroke amount and the opening area of the ride valve 31A, and FIG. 9 is a time chart. Figure 7 shows the ride valve 3 1 In order to explain the configuration of A, the configurations of the boom valve 29 and the speed increasing valve 33 are omitted.

[0102] The traveling vibration suppressing device 20A of the second embodiment is different from the traveling vibration suppressing device 20 of the first embodiment mainly in the configuration of the ride valve 31A and is partially the same as that of the first embodiment. Are denoted by the same reference numerals, and description thereof is omitted.

[0103] In Fig. 7, the traveling vibration suppressing device 20A has a configuration in which the ride valve 31A is switched to three positions. Further, a boom pressure sensor 81 for detecting the pressure of the bottom chamber 11a of the boom cylinder 11 and an accumulator pressure sensor for detecting the pressure of the accumulator 27 are provided. The controller 57a outputs a control signal to the proportional control valve 56b by receiving signals from both the pressure sensors 81 and 82.

[0104] The ride valve 31A has a connection position (C) for connecting the port 3 la and the port 3 le between the operation position (A) and the non-operation position (B) of the ride valve 31 in the first embodiment. are doing. Since the configuration at the operating position (A) and the non-operating position (B) have the same configuration as the configuration in the first embodiment, the configuration at the connection position (C) will be mainly described below.

[0105] At the connection position (C), the ride valve 31A connects the port 31a and the port 31e via a throttle formed in the ride valve 31A. At the connection position (C), the pressurized oil of the accumulator 27 can be discharged to the tank 23 via the throttle.

In the second embodiment, as the pressure accumulated in the accumulator 27, a pressure equal to or greater than the maximum pressure of the sum of the pressure due to the mass of the working device 3 and the pressure due to the mass of the earth and sand loaded on the packet is accumulated. I have. Thus, even if the mass of the working device 3 changes and the pressure of the boom cylinder 11 changes, part of the pressure of the accumulator 27 can be released to the tank 23 using the connection position (C), and the accumulator 27 The pressure can be easily adjusted to the pressure in the bottom chamber 1 la of the boom cylinder 11.

Next, the operation of the traveling vibration suppression device 20A will be described. First, the operation of the ride valve 31A will be described with reference to FIGS. 7, 8, and 9, and then the operation of suppressing the pressure pulsation of the boom cylinder 11 by the traveling vibration suppression device 20A provided in the wheel loader 1 will be described. .

[0108] As shown in Fig. 7, when the traveling vibration suppression device 20A is not operating, as in the first embodiment. In other words, the controller 57a lowers the pressure of the proportional control valve 56b and sets the ride valve 31A to the non-operation position (B). At this time, the opening area Sa between the port 31d and the port 31a is connected in the state of the area A1, the discharge pressure oil of the hydraulic pump 21 is reduced to the pressure set by the charging pressure reducing valve 66, and then accumulated in the accumulator 27. Can be.

[0109] During operation, the controller 57a sequentially increases and outputs a control current as shown in FIG. 9 (a) to the proportional control valve 56b from time T11 to time T13 shown in FIG. You. The proportional control valve 56b receives the control signal from the controller 57a, and supplies the pilot pressure of the control pump 59 to the pilot chamber 56a of the ride valve 31A while gradually increasing the pilot pressure.

As a result, as shown in FIG. 9 (b), the spool of the ride valve 31A increases its stroke, and as shown in FIGS. 8 and 9 (c), the port 31d and the port 31a The opening force of the opening area A1 is also gradually reduced.

[0111] When the stroke amount of the spool of the ride valve 31A reaches the stroke amount L1 on the way to the force Lhalf, that is, at time T12 in Fig. 9, the opening area Sa communicating the port 31d and the port 31a becomes zero (AO). Become. Further, even after time T12, the opening area Sa is maintained at zero (AO).

[0112] From time T12 to time T13, the controller 57a increases the control current, and sets the ride valve 31A to the connection position (C) in FIG. At this time, the spool of the ride valve 31A gradually increases the stroke amount near half the maximum stroke amount Lmax Lhal as shown in FIG. 8B. Further, as shown in FIG. 8D, the opening area Sd connecting the port 3 la and the port 3 le is increased, and the area An is set at the time T13.

[0113] The interval from time T13 to time T14 is a period during which the pressure of the accumulator 27 is reduced to the pressure of the bottom chamber 11a. During the same period, the pressure of the accumulator 27 detected by the pressure sensor 82 and the pressure of the accumulator 27 are detected by the pressure sensor 81. It is determined by the magnitude of the pressure difference from the pressure in the bottom chamber 11a. Between the time T14 and the time T15, the spool of the ride valve 31A gradually increases the stroke amount Lhal as shown in FIG. 8 (b) while the stroke amount Lhal is gradually increased as shown in FIG. 8 (d). The opening area Sd communicating the port 31e with the port 31e is reduced, and the area is set to zero (AO) at time T15. Thereby, the pressure of the accumulator 27 can be made equal to the pressure of the bottom chamber 11a. [0114] After time T15, the same control as that after time T2 in the first embodiment is performed. For this reason, the description after time T15 is omitted with the description after time T2 in the first embodiment. The switching speed of the spool of the ride valve 31A can be controlled by the magnitude of the control current output from the controller 57a to the proportional control valve 56b. By controlling the magnitude of the control current in the same manner as in the first embodiment, the switching speed of the ride valve 31A can be set freely.

[0115] When the traveling of the wheel loader 1 is completed and the operator turns off a switch (not shown) for controlling the proportional control valve 56b, the ride valve 31A returns to the inoperative position (B). At this time, the opening area Sa returns from the state of zero (AO) to the state of the opening area of A1, and the opening areas Sb and Sc return to the state of zero force (AO) of the opening areas A3 and A4, respectively.

[0116] Next, the operation of the traveling vibration suppression device 20A will be described using the transport operation of the wheel loader 1, but the operation that is substantially the same as that of the first embodiment can be performed. I do.

[0117] When the operator turns on a switch (not shown) that controls the proportional control valve 56b while the wheel loader 1 is traveling, the controller 57a causes the boom cylinder 11 generated according to the amount of sediment loaded on the working device 3 to move. The pressure Pb in the bottom chamber 1 la is input as the detected pressure from the boom pressure sensor 81. Further, the accumulator pressure Pa stored in the accumulator 27 is input as the detection pressure from the accumulator pressure sensor 82.

[0118] The controller 57a obtains a differential pressure between the pressure Pb of the bottom chamber 11a and the accumulator pressure Pa. When the differential pressure is large, the controller 57a outputs a control current to the proportional control valve 56b to plot the spool of the ride valve 31A. 9 Set the stroke amount of the half stroke shown in (b) to Lhalf. As a result, the ride valve 31A is at the position (C), and the pressure in the accumulator 27 is reduced.

[0119] The controller 57a maintains the ride valve 31A at the (C) position until the pressure difference between the pressure Pb of the bottom chamber 11a and the accumulator pressure Pa falls within a predetermined allowable range. When the differential pressure falls within the allowable range, the control current is output again to the proportional control valve 56b, and the spool of the ride valve 31A is moved up to the maximum stroke amount Lmax.

[0120] The ride valve 31A is in the operating position (A), and the accumulator 27 and the bottom of the boom cylinder 11 The chamber 11a is connected with an opening area A3, and the tank 23 and the head chamber lib of the boom cylinder 11 are connected with an opening area A4.

[0121] When the wheel loader is run with the ride valve 31A in the operating position (A), the bottom chamber of the boom cylinder 11 that is generated when the boom 10 is pushed up by a boom 10 as in the case of the tire, for example, as in the first embodiment. The pressure fluctuation of 11a can be suppressed. The accumulator 27 is connected to the accumulator 27 and the bottom chamber 11a after the pressure of the accumulator 27 is almost equal to the pressure of the bottom chamber 1 la, and then the boom cylinder 11 is suddenly moved when the accumulator 27 is connected. Extension can be prevented.

[0122] In the above description, the traveling vibration in a state where the opening area Sb of the ride valve 31A is set to the upper limit opening area A3 that can be opened, and the opening area Sc is set to the upper limit area A4 that can be opened. The operation of the suppression device has been described. However, when the pressure in the bottom chamber 11a rises, the opening area Sb is kept at the upper limit opening area A3, so that the pressure in the bottom chamber 11a is quickly absorbed by the accumulator 27 while the flow path resistance is small, and the bottom chamber 11a is used. At the time of the pressure drop of 11a, the upper limit area of the opening area Sb may be set to an opening area smaller than the area A3, the resistance may be slightly increased, and the pressure oil having the accumulator force may be slowly supplied to the bottom chamber 11a.

Example 3

[0123] Next, a traveling vibration suppressing device 20B according to a third embodiment of the present invention will be described. FIG. 10 is a circuit diagram of the ride valve 31B and the control unit, FIG. 11 is a diagram for explaining the relationship between the stroke and the opening area of the ride valve 31B, and FIG. 12 is a time chart. The traveling vibration suppressing device 20B differs from the first traveling vibration suppressing device 20 mainly in the configuration of the ride valve 31B, and the same components as in the first embodiment are the same. The description is omitted by attaching reference numerals. FIG. 10 omits the configurations of the boom valve 29 and the speed increasing valve 33 to explain the configuration of the ride valve 31B.

[0124] In Fig. 10, the traveling vibration suppressing device 20B has a configuration in which the ride valve 31B is switched at three positions. Further, a boom pressure sensor 81 for detecting the pressure of the bottom chamber 11a of the boom cylinder 11 and a running state detecting sensor 84 for detecting the running state of the vehicle are provided. The controller 57b receives signals from the boom pressure sensor 81 and the traveling state detection sensor 84. And outputs a control signal to the proportional control valve 56b.

[0125] The ride valve 31B has a connection position (D) for connecting the port 31a and the port 31b between the operation position (A) and the non-operation position (B) of the ride valve 31 of the first embodiment. Have been. That is, at the connection position (D) of the ride valve 31B, the accumulator 27 and the bottom chamber 1 la of the boom cylinder 11 are connected via the variable throttle 86.

As the variable throttle 86, for example, a plurality of tapered slit grooves or the like extending from the port 31a to the port 31b are provided on the spool of the ride valve 31B in the circumferential direction of the spool, and the variable throttle 86 is moved along with the movement of the spool. By changing the opening area of the plurality of slit grooves, the opening area Sa communicating the port 31a and the port 31b can be made variable.

[0127] Examples of the traveling state detection sensor 84 include a speed sensor, a sensor that can detect the speed stage of the transmission and the rotational speed of the engine, a sensor that can detect the speed stage of the transmission and the stroke position of the accelerator petal, In addition, sensors that can detect the running state of the vehicle, such as an acceleration detection sensor that detects acceleration and deceleration of the vehicle and a GPS (Global Positioning System) sensor that can detect the current position of the vehicle, can be used.

When the ride valve 31B is deactivated, the controller 57b lowers the pilot pressure output from the proportional control valve 56b to position the ride valve 31B at the non-operation position (B) as in the first embodiment. . As a result, the hydraulic pump 21 and the accumulator 27 are connected via the charging pressure reducing valve 66 with the opening area Sa connecting the port 31d and the port 31a as the area A1.

[0129] When operating ride valve 31B, controller 57b determines the pilot pressure output from proportional control valve 56b based on the respective detection information obtained from traveling state detection sensor 84 and boom pressure sensor 81. Control is performed so that a predetermined pressure is obtained. Thereby, the ride valve 31B is switched to the connection position (D), and the accumulator 27 and the bottom chamber 11a of the boom cylinder 11 are connected via the variable throttle 86.

[0130] At this time, the controller 57b controls the proportional control valve 56b such that, for example, when the vehicle speed is high, and when Z or the load weight is large, the opening area of the variable throttle 86 is reduced, and the throttle is controlled. Strengthen. Conversely, when the vehicle speed is low, and when the Z or the load weight is small, the aperture of the variable aperture 86 is controlled to be large so that the aperture is weakened. [0131] The operation of the ride valve 31B will be described with reference to the relationship diagram between the stroke and the opening area in Fig. 11 and the time chart in Fig. 12.

As shown in FIG. 12 (a), the controller 57b sequentially increases the control current and outputs the control current to the proportional control valve 56b from time T21 to time T24. The proportional control valve 56b receives a control signal from the controller 57b and gradually increases the pilot pressure supplied to the pilot chamber 56a of the ride valve 31B.

When increasing the opening area of the variable stop 86, the controller 57b outputs a control current having a large gradient to the proportional control valve 56b as shown by a solid line (I) in FIG. When the opening area of the variable throttle 86 is reduced, a control current having a small gradient is output from the time T22 to the proportional control valve 56b as shown by a two-dot chain line (II).

In the case where the opening area of the variable throttle 86 is reduced, the control current from the controller 57b may be output to the proportional control valve 56b as a control current having a small gradient from time T21. However, in order to shorten the time required for disconnecting the connection between the hydraulic pump 21 and the accumulator 27, that is, the time required for the spool of the ride valve 31B to reach the stroke amount L1, the control current having a small gradient from time T22 is also required. It is desirable to output from the controller 57b to the proportional control valve 56b!

[0135] As a result, the stroke of the spool of the ride valve 31B increases as shown in FIG. 12 (b). As shown in FIG. 11, when the stroke of the spool of the ride valve 31B exceeds L1, that is, in the solid line of FIG. 12 (c), the opening area Sa from the port 31d to the port 3la is changed from the time T22 to the area Sa after the time T22. Zero (AO).

[0136] From the time T22 to the time T24, the controller 57b continues to increase the control current, the spool of the ride valve 31B increases the stroke amount, and the stroke amount of the spool of the ride valve 31B decreases to L1. If it exceeds, the ride valve 31B switches to the connection position (D) in FIG.

[0137] When the stroke amount of the spool of the ride valve 31B is larger than L1, the ride valve 31B is connected to the port 31a and the port 31b as shown in Figs. 11 and 12 (d) and (e). The opening area Sb and the opening areas Sc of the ports 31c and 31e are gradually increased. As shown in FIG. 11, the opening area Sc of the port 31c and the port 31e can be fully opened when the spool of the ride valve 31B exceeds the stroke amount L1. At this time, the controller 57b outputs a control current corresponding to the detection signals from the boom pressure sensor 81 and the traveling state detection sensor 84 to the proportional control valve 56b, and outputs the control current from the proportional control valve 56b. Control the pilot pressure. For example, when increasing the aperture area of the variable throttle 86 as described above, the controller 57b outputs a control current having a large gradient to the proportional control valve 56b as shown by a solid line (I) in FIG. I do. When the opening area of the variable throttle 86 is reduced, a control current having a small gradient is output to the proportional control valve 56b as shown by a two-dot chain line (II).

[0139] From time T22 to time T23, the spool of the ride valve 31B has a large control current as shown by a solid line (I) in FIG. 12 (a), and in the case shown by a solid line in FIG. 12 (b). Thus, the stroke amount increases. Thereby, as shown in FIG. 12D, the opening area Sb of the boom cylinder 11 and the accumulator 27 can be increased to the area A3 as shown by the solid line (III).

When the control current is small as shown by the two-dot chain line (II) in FIG. 12 (a), the spool of the ride valve 31B has a small stroke amount as shown by the two-dot chain line in FIG. 12 (b). Become. The opening area Sb of the boom cylinder 11 and the accumulator 27 can be increased to an area An smaller than the area A3 as shown by a two-dot chain line (IV) in FIG.

[0141] Similarly, as shown in Fig. 12 (e), the opening area Sc connecting the tank 23 and the head chamber lb of the boom cylinder 11 has an area A4 as shown by the dotted line (V) when the control current is large. It can be large. When the control current is small, it can be increased to an area Ar smaller than the area A4 as shown by the two-dot chain line (VI).

[0142] In the solid line in Fig. 12 (b), after time T23, and in the two-dot chain line in Fig. 12 (b), after time T24, the spool of the ride valve 31B has a constant stroke amount, Areas Sb and Sc are also constant. The upper limit opening area that can be opened as the opening areas Sb and Sc is determined by a control current value stored in advance corresponding to detection signals from the boom pressure sensor 81 and the traveling state detection sensor 84 by a solid line ( The opening area between III) and the two-dot chain line (IV) and the opening area force between the solid line (III) and the two-dot chain line (IV) can be selected as appropriate.

[0143] Also, between time T24 and time T25, for example, when the load weight is reduced halfway and the detection pressure from the boom pressure sensor 81 decreases, the controller 57b detects the load. The control current corresponding to the pressure is output to the proportional control valve 56b, and the upper limit opening areas that can be opened as the opening areas Sb and Sc are as shown in Figs. 12 (d) and (e), respectively. , The opening area Awl and the opening area Arl can be changed from the state of the opening area Ar

[0144] Conversely, for example, when the load becomes heavier on the way and the detected pressure from the boom pressure sensor 81 increases, the controller 57b supplies a control current corresponding to the detected pressure to the proportional control valve 56b. The upper limit opening area which can be output and opened as the opening area Sb can be reduced to the area Aws as shown in FIG. Similarly, the upper limit opening area that can be opened as the opening area Sc can be reduced.

[0145] From time T25 to time T26, the controller 57b outputs a signal whose time T21 force is the reverse of that at the time T24, and similarly to the first embodiment, the opening area Sb between the boom cylinder 11 and the accumulator 27. The opening area Sc of the boom cylinder 11 and the tank 23 is returned to zero when the stroke amount of the spool of the ride valve 31B is returned to L1, and the opening area of each is returned to zero, and the bottom chamber 11a of the accumulator 27 and the hydraulic pump 21 Can be returned to the opening area A1 when returning to the stroke stroke force LO of the spool of the ride valve 31B.

[0146] Next, the operation of the traveling vibration suppression device 20B will be described using the transporting operation of the wheel loader 1. Since the operation can be performed in substantially the same manner as in the first embodiment, different operations during traveling will be described. .

[0147] When the operator turns on a switch (not shown) that controls the proportional control valve 56b during traveling of the wheel loader 1, the controller 57b causes the boom cylinder 11 generated according to the amount of sediment loaded on the working device 3 to move. The pressure Pb of the bottom chamber 1 la is input as the detection pressure from the boom pressure sensor 81. Further, the controller 57b inputs a detection signal from the traveling state detection sensor 84.

[0148] Based on the pressure Pb of the bottom chamber 11a detected by the boom pressure sensor 81, the controller 57b determines the opening area of the variable throttle 86 corresponding to the pressure Pb obtained and stored in advance from a test or the like, and the corresponding area. The stroke amount of the ride valve 31B with respect to the spool is calculated. The control current is output to the proportional control valve 56b so that the stroke of the ride valve 31B becomes the stroke amount. [0149] The proportional control valve 56b supplies a pilot pressure corresponding to the signal of the controller 57b to the ride valve 31B. Thereby, for example, the spool of the ride valve 31B moves to the stroke amount Lm in FIG. The ride valve 31B is at the connection position (D), and connects the accumulator 27 and the bottom chamber 11a of the boom cylinder 11 with the opening area An of the variable throttle 86. The opening area Sc connecting the tank 23 and the head chamber l ib of the boom cylinder 11 is connected by the area Ar. Thus, the accumulator 27 and the bottom chamber 11a of the boom cylinder 11 are connected at the same pressure via the ride valve 31B.

[0150] As shown in Fig. 12 (e), the opening area Sc that connects the tank 23 and the head chamber l ib of the boom cylinder 11 is between time T22 and time T23 (in the two-dot chain line, until time T24). In other words, during the transfer of the spool of the ride valve 31B from the stroke amount L1 to the stroke amount Lm, the opening area Sc is sequentially increased to the area Ar with an increase in the movement amount of the spool.

[0151] The ride area can be run with the opening area Sb and the opening area Sc of the ride valve 31B switched to the area An and the area Ar controlled by the controller 57b. When the controller 57b inputs the traveling state of the wheel loader 1 by the traveling state detection sensor 84, for example, the vehicle speed information, the optimum opening area of the variable diaphragm 86 is determined from the relationship between the vehicle speed information and the opening area stored in the storage device in advance. Ask for Awl. When the controller 57b determines that it is necessary to change the opening area of the variable aperture 86 to the state of the area An and the state of the area Awl, the control signal that the opening area of the variable aperture 86 becomes the area Awl is sent to the proportional control valve 56b. Output.

[0152] For example, when the controller 57b determines that the vehicle speed input from the traveling state detection sensor 84 is faster than a predetermined speed, the controller 57b reduces the pilot pressure output from the proportional control valve 56b to reduce the stroke of the spool of the ride valve 31B. Decrease volume from Lm to Lms. Thereby, as shown in FIG. 11, the opening area Sb of the variable throttle 86 connecting the accumulator 27 and the bottom chamber 1 la of the boom cylinder 11 can be reduced to the area Aws from the state of the area An.

[0153] When the vehicle speed input from the traveling state detection sensor 84 is lower than the predetermined speed, the controller 57b increases the pilot pressure output from the proportional control valve 56b to increase the stroke amount of the spool of the ride valve 31B. From Lm to Lml. With this, The opening area Sb of the variable throttle 86 connecting the motor 27 and the bottom chamber 1 la of the boom cylinder 11 can be changed to the area Awl where the state force of the area An is also increased.

[0154] With this, in the traveling vibration suppressing device 20B, the opening area Sb of the variable throttle 86 can be controlled to, for example, an area suitable for the vehicle speed and the loading capacity of the working device 3, so that the bottom chamber of the boom cylinder 11 can be controlled. Pressure pulsation occurring at 11a can be optimally suppressed according to the running state and the loading state.

[0155] The pressure pulsation generated in the bottom chamber 11a can be suppressed by the accumulator 27 via the ride valve 31B having the optimal opening area Sb.

[0156] Further, for example, when the vehicle body 7 climbs on a stone or the like and rises, the pressure in the bottom chamber 11a of the boom cylinder 11 increases as the boom 10 tries to stay at the same height position as before. At this time, the increased pressure in the bottom chamber 11a can be quickly supplied to the accumulator 27 and absorbed by the opening areas Sb and Sc in the ride valve 31B. Further, when the vehicle body 7 descends into a dent or the like, the pressure oil can be slowly supplied from the accumulator 27 to the bottom chamber 11a of the boom cylinder 11 to control the boom 10 not to be pushed up.

[0157] The switching speed of the spool of the ride valve 31B can be freely set by a control current output from the controller 57b to the proportional control valve 56b in accordance with signals from the pressure sensor 81 and the traveling state detection sensor 84. .

Example 4

Next, a traveling vibration suppressing device 20C according to the fourth embodiment will be described. FIG. 13 shows a partial configuration of the traveling vibration suppressing device 20C. In the fourth embodiment, the configuration at the connection position (D) of the ride valve 31B in the third embodiment is configured as a variable throttle valve 88 independently of the ride valve 31. Further, a first proportional control valve 90 for controlling the variable throttle valve 88 is additionally provided. The other configuration has the same configuration as the configuration in the third embodiment. Therefore, the same components as those in the first embodiment to the third embodiment are denoted by the same reference numerals, and the description thereof is omitted. FIG. 13 omits the configurations of the boom valve 29 and the speed increasing valve 33 to explain the configuration of the ride valve 31!

[0159] The variable throttle valve 88 is disposed between the accumulator 27 and the ride valve 31, and the first proportional control It operates by receiving pilot pressure from the valve 90 into the control room 88a. The connection area between the accumulator 27 and the bottom chamber 1 la of the boom cylinder 11 is made variable by a variable throttle valve 88. The variable throttle valve 88 switches between a variable throttle position (E) when receiving pilot pressure from the first proportional control valve 90 and an open position (F) when not receiving pilot pressure. When the variable throttle valve 88 is at the open position (F), the accumulator 27 and the hydraulic pump 21 are connected via the ride valve 31 to reduce the resistance and discharge the hydraulic oil from the hydraulic pump 21 to the accumulator 27. To make it easier to supply.

[0160] The first proportional control valve 90 is controlled by receiving a control current from the controller 57c. The first proportional control valve 90 sets the variable throttle valve 88 to a variable throttle position (E) when receiving a control current from the controller 57c, and controls the opening area of the variable throttle according to the control current value. When the first proportional control valve 90 does not receive the control current (when the current is zero), the first proportional control valve 90 is deactivated, and the variable throttle valve 88 is set to the open position (F).

[0161] The operation of the ride valve 31 and the variable throttle valve 88 used in the traveling vibration suppressing device 20C will be described with reference to the circuit diagram of FIG. When the controller 57c outputs the control current to the proportional control valve 56b while increasing the control current, the spool of the ride valve 31 is stroked as described in the first embodiment, and the opening communicating the port 3 la and the port 3 Id is opened. After the area Sa is gradually decreased and the state force of the area A1 is set to zero (AO), the state where the area is zero is maintained.

[0162] When the spool of the ride valve 31 moves by a predetermined amount due to the control current from the third controller 57c to the proportional control valve 56b, the opening area Sb communicating the port 31a and the port 31b is sequentially opened to the area A3. Further, the opening area Sc communicating the port 31a and the port 31e can be sequentially opened up to the area A4, or can be opened all at once to the area A4.

[0163] According to the magnitude of the control current from the third controller 57c to the first proportional control valve 90, the variable throttle valve 88 changes the throttle area until the maximum throttle opening at the variable throttle position (E) is reached. Can be done.

[0164] Upon receiving signals from the boom pressure sensors 81 and Z or the traveling state detection sensor 84, the controller 57c obtains a signal based on the relationship between the detection values of the two sensors stored in the storage device in advance and the opening area. (1) The control current is output to the proportional control valve 90, and the detection value detected by both sensors Change the throttle of the variable throttle valve 88 so that the optimal opening area corresponding to is obtained.

[0165] Accordingly, the accumulator 27 and the bottom chamber 11a of the boom cylinder 11 are configured such that the opening area of the throttle in the variable throttle valve 88 and the opening area Sb that connects the port 31a and the port 31b in the ride valve 31 are different from each other. Will be connected via At this time, the opening area Sc of the ride valve 31 that connects the tank 23 and the head chamber l ib of the boom cylinder 11 becomes a constant area A4, and the pressure between the tank 23 and the boom cylinder 11 is increased. The amount of oil supply and discharge has been increased to prevent the generation of vacuum.

[0166] Thereby, the opening area for communicating the accumulator 27 with the bottom chamber 11a of the boom cylinder 11 can be controlled in two stages.

[0167] For example, when the loaded weight detected by the boom pressure sensor 81 is large, or when the vehicle speed detected by the traveling state detection sensor 84 is high, the controller 57c outputs a large control current to the first proportional control valve 90. And the opening area of the variable throttle valve 88 can be reduced to increase the throttle.

[0168] Conversely, when the load weight is small and the vehicle speed is low, a small control current is output to the first proportional control valve 90 to increase the opening area of the variable throttle valve 88, thereby making it possible to weaken the throttle.

[0169] Next, the operation of the traveling vibration suppression device 20C will be described using the transporting operation of the wheel loader 1. However, since substantially the same operation as that of the third embodiment can be performed, the traveling of the wheel loader 1 can be performed. An operation different from that of the third embodiment at the time will be described.

[0170] During traveling, when an operator turns on a switch (not shown), the controller 57c outputs a control signal to the proportional control valve 56b, and causes the ride valve 31 to perform a full stroke to the operating position (A). Further, the controller 57c inputs the pressure Pb of the bottom chamber 11a detected by the boom pressure sensor 81, and uses the control current for obtaining the opening area of the variable throttle valve 88 for the pressure Pb obtained and stored in advance by a test or the like. Then, a control current is output to the first proportional control valve 90.

[0171] The first proportional control valve 90 that has received the control current activates the predetermined throttle port pressure to the variable throttle valve 88 to make the opening area of the variable throttle a predetermined opening area. The accumulator 27 and the bottom chamber 1 la of the boom cylinder 11 are connected via a diaphragm having a predetermined opening area. [0172] Thus, the accumulator 27 and the bottom chamber 11a of the boom cylinder 11 are connected to each other through the opening area Sb of the ride valve 31 and the opening area of the variable throttle valve 88 to have the same pressure.

[0173] Next, the wheel loader 1 travels, and the controller 57c inputs, for example, information on the vehicle speed from the traveling state detection sensor 84. At this time, the relationship between the vehicle speed information and the opening area stored in the storage device in advance, the opening area of the variable throttle obtained, and the opening area of the variable throttle set according to the detection pressure from the boom pressure sensor 81 are obtained. When the difference between the opening areas of the two variable throttles is large, a control current is output to the first proportional control valve 90 to change the throttle of the variable throttle valve 88 so as to have an optimum opening area.

[0174] For example, when the controller 57c receives information from the traveling state detection sensor 84 that the vehicle speed is high, the throttle of the variable throttle valve 88 that connects the accumulator 27 and the bottom chamber 11a of the boom cylinder 11 is throttled to open. Make the area even smaller.

When the controller 57c receives the information that the vehicle speed is low, the controller 57c outputs a control signal for increasing the opening area of the throttle of the variable throttle valve 88 to the first proportional control valve 90. The first proportional control valve 90 receives the control signal from the controller 57c, and controls the pilot pressure to be increased or decreased so as to control the opening area of the throttle in the variable throttle valve 88 from the traveling state detection sensor 84. The opening area can be set according to the detection signal.

[0176] As a result, in the traveling vibration suppression device 20C, the pressure pulsation of the boom cylinder 11 generated by the traveling of the wheel loader 1 matches the detection signal from the boom pressure sensor 81 and / or the traveling state detection sensor 84. The accumulated opening area can be absorbed by the accumulator 27 via the variable throttle valve 88 and the ride valve 31.

In each of the above embodiments, the force described in the example in which the accumulator 27 is connected to the bottom chamber 11a of the boom cylinder 11 is also applied to the configuration in which the accumulator 27 is connected to the head chamber l ib of the boom cylinder 11. The traveling vibration suppressing device according to the present invention can function effectively.

[0178] Although ride valve 31 has been described using a two-position switching valve or a three-position switching valve or the like for ease of description, a servo valve that changes continuously may be used.

The directional control valve 24 includes a boom valve 29 and a speed increasing valve 33 on both sides with the ride valve 31 at the center. The rider explains the configuration of the vehicle. The ride valve 31 and the speed-increasing valve 33 can be provided on both sides with the boom valve 29 in the middle.

[0180] Further, although the change in the opening area of the accumulator 27 and the boom cylinder 11 is shown by a straight line, it can be changed by a curve such as a secondary parabola.

[0181] In the above description, two directional control valves, a boom valve 29 and a packet valve 30, are used as the directional control valves, and the boom valve 29 of the boom directional control valve is disposed on the pump side, and then the boom valve 29 is disposed adjacently. The configuration in which the packet valve 30 is arranged has been described. However, the arrangement configuration as a directional control valve is not limited to this.For example, three or more directional control valves, a packet valve 30 on the pump side, and one of the remaining directional control valves for boom A configuration in which the boom valve 29 of the valve is used may be employed.

Further, the traveling vibration suppressing device can be configured by appropriately combining the first to fourth embodiments.

Industrial applicability

[0182] The traveling vibration suppressing device of the present invention can be used for a device in which pressure pulsation is generated by vibration during traveling of a traveling vehicle.

Claims

The scope of the claims

[1] A hydraulic pump 21, at least one or more actuators 11 operated by hydraulic oil discharged from the hydraulic pump 21, and connected to one of the pressure chambers of at least one of the actuators 11 to reduce the pressure pulsation of the pressure chambers An accumulator 27 to absorb, a directional control valve 29 for controlling pressure oil supplied from the hydraulic pump 21 to the actuator 11, a ride control valve 31, 31A for controlling communication and shutoff between the accumulator 27 and the pressure chamber, In the traveling vibration suppressing device 20 of the working vehicle equipped with 31B,

A travel vibration suppressing device for a working vehicle, wherein the ride control valves 31, 31A, 31B are laminated on the direction control valve 29 by internal piping.

[2] The traveling vibration suppression device according to claim 1,

A first pressure sensor 81 and Z for detecting the load pressure of the actuator 11 or a traveling state detection sensor 84 of the work vehicle are provided,

A travel vibration suppressing device characterized in that a communication opening area of the ride control valve 31B is controlled based on a detection signal from the first pressure sensors 81 and Z or a travel state detection sensor 84.

[3] The travel vibration suppressing device according to claim 2,

A second pressure sensor 82 for detecting the pressure of the accumulator 27 is provided, and the pressure detected by the second pressure sensor 82 by the accumulator 27 is higher than the load pressure of the actuator 11 by the first pressure sensor 81. In this case, the ride control valve 31A is controlled to reduce the pressure of the accumulator 27 to the load pressure of the actuator 11, and thereafter, the accumulator 27 is communicated with the pressure chamber. Traveling vibration suppressing device.

[4] In the travel vibration suppressing device according to claim 1 or 2,

A travel vibration suppressing device, wherein the ride control valve 31B has a variable upper limit opening area that can be opened as the communication opening area.

[5] The travel vibration suppressing device according to claim 4,

The control to reduce the upper limit opening area is performed as the load pressure of the actuator 11 increases and as the traveling speed of Z or the work vehicle 1 increases. A driving vibration suppressing device characterized by being formed.

[6] The traveling vibration suppressing device according to claim 4,

The control to increase the upper limit opening area is performed as the load pressure of the actuator 11 decreases and as the traveling speed of the work vehicle 1 or Z decreases. Traveling vibration suppressing device.

[7] The traveling vibration suppressing device according to claim 1 or 2,

The travel vibration suppressing device, wherein the ride control valve 31 includes a variable throttle 88 that equalizes the pressures of the pressure chamber and the accumulator 27.

[8] The traveling vibration suppressing device according to claim 1 or 2,

A speed increasing valve 33 for supplying pressure oil from the hydraulic pump 21 to the at least one actuator 11 is further provided,

A travel vibration suppressor characterized in that the speed-increasing valve 33 is laminated on the ride control valves 31, 31A, 31B or the directional control valve 29 by internal piping and Z or external piping.