JP2000095134A - Travel curvature compensator for hydraulically driven body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to compensate travel curvatures in both forward and reverse directions accurately when the travel curvatures are different in forward and reverse travel, so that travel curvature can be corrected easily. SOLUTION: Throttle valves 31 32 are provided close to a hydraulic pump 1 and part way along pressurized oil supply conduit lines 21, 22, which run between the pressurized oil discharge openings 1b, 1c of the hydraulic pump 1 and direction control valves 23, 24. The throttle valves 31, 32 serve to bypass pressurized oil P1, P2 along the pressurized oil supply conduit lines 21, 22, and freely adjust the flow rate of the bypass pressurized oil. Similarly, part way along the forward motion hydraulic supply conduit lines 51A, 52A, and part way along the reverse motion hydraulic supply conduit lines 51B, 52B, throttle valves are provided to bypass the pressurized oil in the conduit lines and to freely adjust the flow rate of the bypass pressurized oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for compensating for a running curve when a hydraulically driven traveling body such as a hydraulic shovel travels straight.

[0002]

2. Description of the Related Art A hydraulically driven traveling body such as a hydraulic shovel is provided with left and right hydraulic motors for driving the left and right crawler tracks, respectively, corresponding to the left and right crawler tracks. A hydraulic pump is provided for each of the left and right hydraulic motors.

[0003] When a hydraulically driven traveling body travels straight, if there is a difference in discharge flow rate between these two hydraulic pumps, the operator will not travel straight even though the operator is performing the straight traveling operation.
Running bend occurs.

[0004] The running bend occurs because the left and right crawler belts are driven using separate hydraulic devices (hydraulic pump, directional control valve, pressure oil supply line, hydraulic motor, etc.) for each of the left and right tracks. That's why. Even if the hydraulic pumps provided on the left and right sides have the same displacement (cc / rev), the rotation of the left and right crawler belts will not be the same due to the following reasons, and the vehicle will not run completely straight.

(1) Difference in volumetric efficiency between left and right hydraulic pumps (difference in leakage due to temperature, difference in component clearance due to component accuracy, etc.) (2) Difference in pressure loss between left and right piping (difference in piping length, piping (3) Difference in volumetric efficiency between left and right hydraulic motors (difference in leakage due to temperature, difference in component clearance due to component accuracy, etc.) (4) Difference in drive resistance between left and right crawler belts (installation error) (5) Bending of the right and left crawler belts themselves (6) Difference between left and right of resistance difference of traveling road surface (resistance coefficient of traveling road surface, levelness, etc.).

Therefore, conventionally, the vehicle is assembled after minimizing the rotational difference between the left and right crawler belts by, for example, improving the precision of hydraulic components in consideration of the causes (1) to (6). I was For example, tightening the specification of the flow difference of hydraulic pump discharge flow, length of piping path,
There is a design in which the thickness, the bent portion, and the like are the same in the left and right pipes, and the pipe resistance is equal in the left and right pipes.

[0007] However, even if measures are taken to improve the precision of the parts in this way, the vehicle actually assembled may bend individually.

For this reason, countermeasure parts have been incorporated in order to correct the running curve of the vehicle after the actual vehicle has been assembled. For example, a fixed throttle, which becomes a resistance of the pressure oil, is incorporated in the middle of the pressure oil supply pipe. In addition, a stopper for limiting an operation stroke is incorporated in the operation lever. Further, a stopper for limiting the operation amount of the directional control valve (operating valve) was incorporated.

However, when assembling a vehicle with the rotational difference between the left and right crawler belts being as small as possible by improving the precision of parts of hydraulic equipment in consideration of the causes (1) to (6), etc. A problem arises in that the number of parts manufacturing steps increases, the number of parts increases, and the degree of freedom in piping configuration decreases.

In addition, when a countermeasure component is incorporated after assembling the actual vehicle, there is a problem that the trouble of incorporating a new countermeasure component increases. In addition, when a fixed aperture is incorporated, it is necessary to select and install a fixed aperture suitable for the bending of each vehicle, and the operation becomes complicated.

In order to solve such a problem, Japanese Utility Model 8
In Japanese Patent Application Laid-Open No. -9236, a traveling hydraulic circuit of a construction machine is configured as shown in FIG.

In the hydraulic circuit shown in FIG. 9, hydraulic pumps are provided corresponding to the left and right traveling hydraulic motors 25 and 26, respectively. Also, the left and right traveling hydraulic motors 25, 26
Directional control valves 23 and 24 are provided respectively. Then, a pressure oil supply pipe 51 (51A, 51A) between each of the directional control valves 23, 24 and the traveling hydraulic motors 25, 26.
B), 52 (52A, 52B) have a variable throttle valve 91,
92 are provided. 25A and 26A are forward pressure oil inflow ports of the hydraulic motors 25 and 26, respectively.
B and 26B are hydraulic oil inflow ports for reverse movement of the hydraulic motors 25 and 26, respectively.

Therefore, when the operator operates the left crawler operation lever 27 to the forward side to switch the direction control valve 23 to the forward position, the discharge pressure oil of the hydraulic pump passes through the forward pressure oil supply line 51A. As a result, the fluid flows into the forward pressure oil inflow port 25A of the hydraulic motor 25. As a result, the hydraulic motor 2
5 rotates in the normal rotation direction, and the left crawler belt is rotated in the forward direction.
The pressure oil that has flowed out from the opposite port 25B of the hydraulic motor 25 is discharged through a pipe 51B.

Similarly, when the operator operates the right crawler operation lever 28 forward, the hydraulic motor 26 rotates in the forward direction in response to this operation, and the right crawler is rotated in the forward direction. As a result, the construction machine goes straight ahead.

Here, when a running curve occurs when the vehicle travels straight in the forward direction, the operator adjusts the left and right variable throttle valves 91 and 92. As a result, the pressure oil flowing through the forward pressure oil supply pipes 51A and 52A is bypassed to the pipes 95 and 96 by a predetermined flow rate, respectively, and is discharged to the return pipe. For this reason, the flow rate difference of the pressure oil flowing through the left and right pressure oil supply pipelines 51A and 52A is corrected, and the traveling bending of the construction machine when moving forward is corrected.

As described above, according to the invention described in this publication, the running curve can be corrected by adjusting the variable throttle valve according to the running curve of each vehicle.
Therefore, there is no need to increase the precision of the parts, and the problems of increasing the number of parts manufacturing steps, increasing the number of parts, and reducing the degree of freedom in the piping configuration do not occur. In addition, since the work of selecting and installing a fixed stop suitable for the bending of each vehicle is not required and only the work of adjusting the degree of stop is required, the workability is improved.

[0017]

However, according to the hydraulic circuit described in the above publication, the variable throttle valves 91 and 92 are disposed between the directional control valves 23 and 24 and the hydraulic motors 25 and 26. That is, the inlets 25A, 26A of the hydraulic motors 25, 26
And outlets 25B, 26B. Therefore, the variable throttle valves 91, 92 are arranged at positions close to the hydraulic motors 25, 26.

FIG. 2 is a perspective view showing the structure of the excavator 80. As shown in FIG.

At the rear end of the upper swing body 81 of the hydraulic excavator 80, an engine hood 85 for inspecting and maintaining the engine 2 is provided. The engine hood 85 is openable and closable. The engine hood 85 is opened at the time of inspection and maintenance of the engine.

However, the hydraulic motors 25, 26 are arranged near the crawler belts 83, 84 of the lower traveling body 82. For this reason, the position of the engine hood 85 of the upper swing body 81 is far from the position of the hydraulic motors 25 and 26, and the operator cannot reach it.

Therefore, the variable throttle valves 91 and 92 provided close to the hydraulic motors 25 and 26 are connected to the engine hood 8.
Adjustment from the position 5 becomes impossible.

Therefore, in the prior art, the variable throttle valve must be adjusted at the production stage of the construction machine, and the variable throttle valve is adjusted according to the running curve of each vehicle after the production and assembly or at the time of actual running by the user. The valve could not be easily adjusted.

Accordingly, the first object of the present invention is to make it possible to easily adjust the variable throttle valve with good workability in accordance with the running curve of each vehicle after the production and assembly of the hydraulically driven running body or during actual running by the user. It is to be solved.

By the way, in a construction machine, the amount of bending and the direction of bending may be different between forward movement and reverse movement.

In the above-mentioned publication, the same throttle valve as that used when the vehicle is moving forward is used for correcting the running curve when the vehicle is moving backward.

That is, when a running curve occurs when the vehicle is traveling straight in the reverse direction, the operator adjusts the left and right variable throttle valves 91 and 92. As a result, the reverse pressure oil supply pipes 51B, 52B
Lines 95 and 9 in which the pressure oil flowing through
6 are respectively bypassed by a predetermined flow rate. For this reason, the flow rate difference of the pressure oil flowing through the left and right pressure oil supply pipes 51B and 52B is corrected, and the traveling bending of the construction machine when moving backward is corrected.

However, the throttle valves 91 and 92 are set at the time of forward movement.
Once is adjusted, if the traveling bend differs between forward and reverse, it becomes impossible to correct the traveling bend during reverse by the difference (conversely, the throttle valve 91, Once the 92 is adjusted, it becomes impossible to correct the running curve when moving forward.)

In view of the above, the present invention is to correct the running curve of a hydraulically driven traveling body in both forward and reverse directions when the amount of bending and the direction of bending are different between forward and reverse. As a second problem to be solved.

[0029]

Accordingly, in the first invention of the present invention, in order to achieve the first object, the left and right crawler belts (8) of the hydraulically driven traveling body (80) are provided.
3 and 84) or wheels, respectively, and left and right hydraulic actuators (25 and 26) for driving these left and right crawler tracks (83 and 84) or wheels, respectively, and the engine (2) driven by the engine (2). 2) and each hydraulic oil discharge port (1b, 1) of the hydraulic pump (1) provided corresponding to the left and right hydraulic actuators (25, 26).
c) and the left and right hydraulic actuators (25, 26)
The left and right hydraulic actuators (25, 2) control the direction of the flow of pressure oil discharged from the pressure oil discharge ports (1b, 1c) of the hydraulic pump (1).
6) to supply pressure oil to each of the directional control valves (23, 2
4) In the traveling bend correction device for a hydraulically driven traveling body that corrects the traveling curvature of the hydraulically driven traveling body (80) when traveling straight ahead, the hydraulic fluid traveling body (80) has a hydraulic oil discharge port (1).
b, 1c) and the direction control valve (23, 24), at a position close to the hydraulic pump (1) in the middle of the pressure oil supply pipe (21, 22). , 22) are provided with throttle valves (31, 32) that bypass the pressure oil (P1, P2) above and that can adjust the flow rate of the bypassed pressure oil.

The first invention will be described with reference to FIGS.

According to the first invention, the hydraulic oil supply pipes 21 and 22 between the hydraulic oil discharge ports 1 b and 1 c of the hydraulic pump 1 and the directional control valves 23 and 24 are located near the hydraulic pump 1. The throttle valves 31 and 32 are provided at positions where the pressure oils P1 and P2 on the pipelines 21 and 22 are bypassed and the flow rate of the bypassed pressure oil is adjustable (see FIG. 1).

Here, the hydraulic pump 1 is driven by the engine 2 and is arranged close to the engine 2. For this reason, the position from the position of the engine hood 85 to the hydraulic pump 1 is very close, and the operator can easily reach (see FIG. 2).

Therefore, the throttle valves 31 and 32 provided close to the hydraulic pump 1 can be adjusted very easily from the position of the engine hood 85.

Therefore, it is possible to easily adjust the throttle valves 31 and 32 with good workability according to the degree of bending of each vehicle after production and assembly of the hydraulically driven traveling body 80 or during actual traveling by the user.

According to a second aspect of the present invention, in the first aspect, the throttle valves (31, 32) are connected to the hydraulic pump (1).
It is characterized by being arranged in.

According to the second aspect of the present invention, the hydraulic pump 1 is provided in the middle of the hydraulic oil supply pipes 21 and 22 between the hydraulic oil discharge ports 1 b and 1 c of the hydraulic pump 1 and the direction control valves 23 and 24. Throttle valves 31, 32 that bypass the pressure oils P 1, P 2 on the pipe lines 21, 22 and that can adjust the flow rate of the bypassed pressure oil
(See FIGS. 1 and 3).

Here, the hydraulic pump 1 is driven by the engine 2 and is arranged close to the engine 2. For this reason, the position from the position of the engine hood 85 to the hydraulic pump 1 is very close, and the operator can easily reach (see FIG. 2).

Therefore, the throttle valves 31, 32 provided in the hydraulic pump 1 can be adjusted very easily from the position of the engine hood 85.

Therefore, it is possible to easily adjust the throttle valves 31 and 32 with good workability according to the degree of bending of each vehicle after the production and assembly of the hydraulically driven traveling body 80 or during actual traveling by the user.

In the third aspect of the present invention, in order to attain the second object, the hydraulic drive traveling body (80) is provided corresponding to the left and right crawler tracks (83, 84) or wheels, respectively. Left and right hydraulic actuators (25, 2) for driving left and right crawler tracks (83, 84) or wheels, respectively.
6) and the left and right hydraulic actuators (25, 26)
Directional control valves (23, 23) that are provided corresponding to the hydraulic pumps (1) to control the flow direction of the hydraulic oil discharged from the hydraulic pump (1) and supply the hydraulic oil to the left and right hydraulic actuators (25, 26), respectively. 24) and the directional control valve (23, 2
4) and the hydraulic actuator (25, 26), and the forward hydraulic oil inflow ports (25A, 26A) and the reverse hydraulic oil inflow ports (25B, 26B) of the hydraulic actuator (25, 26). Of the hydraulically driven traveling body (80) having the forward pressure oil supply pipes (51A, 52A) and the reverse pressure oil supply pipes (51B, 52B) for supplying pressurized oil to the vehicle during straight running. In the travel bending correction device for a hydraulically driven traveling body to be corrected, the pressure on the hydraulic pressure supply pipes (51A, 52A) and the pressure oil supply pipes for reverse (51B, 52B) are respectively set in the middle of the pipes. Throttle valves ((31A, 32A), (31B,
32B).

The third invention will be described with reference to FIG.

According to the third invention, the forward pressure oil supply line 5
1A, 52A and hydraulic oil supply pipelines 51B, 52B for reverse travel
The throttle valve (31) which can bypass the pressure oil on the pipeline and adjust the flow rate of the bypassed pressure oil
A, 32A) and (31B, 32B).

When the vehicle is bent while traveling straight in the forward direction, the operator adjusts the left and right throttle valves 31A and 32A provided for forward movement. As a result, the pressure oil flowing through the forward pressure oil supply pipes 51A and 52A is bypassed by a predetermined flow rate and returned to the tanks 72 and 74, respectively. Therefore, the flow rate difference between the pressure oil flowing through the left and right pressure oil supply pipes 51A, 52A is corrected, and the traveling bending of the hydraulically driven traveling body 80 at the time of forward movement is corrected.

On the other hand, if a running curve occurs when the vehicle travels straight in the reverse direction, the operator adjusts the left and right throttle valves 31B and 32B provided for reverse travel. As a result, the pressure oil flowing through the reverse pressure oil supply pipelines 51B and 52B is returned to the tanks 73 and 75 after being bypassed by a predetermined flow rate. For this reason, the flow rate difference between the pressure oil flowing through the left and right pressure oil supply pipes 51B and 52B is corrected, and the traveling bend of the hydraulically driven traveling body 80 during backward movement is corrected.

As described above, according to the third aspect, the throttle valve (31B, 31B, 31B, 32B) is used for 32A. In other words, even when the amount of bending and the direction of bending are different between when the vehicle is moving forward and when the vehicle is moving backward, the running bending is individually corrected.

Therefore, according to the third aspect of the present invention, the traveling curve can be accurately corrected both when the vehicle is moving forward and when the vehicle is moving backward.

[0047]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a hydraulically driven traveling body according to an embodiment of the present invention; The hydraulically driven traveling body is a concept including vehicles other than construction machines without being limited to construction machines such as hydraulic shovels.

FIG. 2 is a perspective view showing the structure of a hydraulic excavator 80 assumed in this embodiment.

The hydraulic excavator 80 is roughly composed of the upper swing body 8.
1 and a lower traveling body 82. An engine hood 85 for inspecting and maintaining the engine 2 is provided at a rear end of the upper swing body 81. The engine hood 85 is openable and closable. The engine hood 85 is
At the time of engine inspection and maintenance, and as described later, the throttle valve 3
It is opened when adjusting 1, 32.

The lower traveling body 82 is constituted mainly by left and right crawler belts 83 and 84 provided on a truck frame. The hydraulic motors 25 and 26 are connected to the crawler belt 8 of the lower traveling body 82.
3 and 84, respectively. That is, the hydraulic motors 25 and 26 are connected to the crawler 8 via a speed reducer (not shown).
3 and 84, respectively. Hydraulic pump 1
Is arranged near the engine 2. Track 83,
Wheels may be used instead of 84. That is, the present invention is also applicable to a wheel-type hydraulically driven traveling body.

FIG. 1 is a hydraulic circuit diagram showing the arrangement of each hydraulic device mounted on the hydraulically driven traveling body (hydraulic shovel 80) of FIG.

The right and left crawler belts 83, 84 of the excavator 80
, Left and right traveling hydraulic motors 25 and 26 for driving the left and right crawler belts 83 and 84, respectively, are provided.

The hydraulic pump 1 is a variable displacement hydraulic pump driven by the engine 2. This hydraulic pump 1
Are provided with respective pressure oil discharge ports 1b, 1c corresponding to the left and right hydraulic motors 25, 26, respectively.

In this embodiment, the traveling hydraulic motor 25,
26 is a pressure oil supply port for supplying pressure oil to the pressure oil discharge port 1
b, 1c are provided, and the swash plate 1a is a pressure oil discharge port 1b,
A so-called 2-flowway type hydraulic pump 1 common to 1c is used. Instead of the two-flowway hydraulic pump 1, two single hydraulic pumps may be used. Alternatively, a hydraulic pump provided with three or more pressure oil discharge ports may be used. In short, any hydraulic pump having at least two pressure oil discharge ports corresponding to the left and right traveling hydraulic motors 25 and 26 may be used. In this specification, “each pressure oil discharge port of a hydraulic pump provided for each of the left and right hydraulic actuators” refers to each pressure oil discharge port provided for a single pump in a two-flowway hydraulic pump. In the configuration using two single hydraulic pumps, the concept includes both the concept of an outlet and each pressure oil discharge port provided in each of the two pumps, and the type of the hydraulic pump is not limited.

The hydraulic pump 1 is also a hydraulic oil supply source for supplying hydraulic oil to a hydraulic actuator for a working machine of the hydraulic shovel 80, that is, a hydraulic cylinder for a boom, a hydraulic cylinder for an arm, and the like. However, those components are omitted in the hydraulic circuit of FIG.

The direction control valves 23 and 24 are provided corresponding to the left and right hydraulic motors 25 and 26, respectively, and control the direction of the flow of the pressure oil discharged from the pressure oil discharge ports 1b and 1c of the hydraulic pump 1. Control supplies hydraulic oil to the left and right hydraulic motors 25 and 26, respectively. The direction control valves 23 and 24 also function as flow rate control valves for controlling the flow rate of the pressure oil. The direction and flow rate of the pressure oil passing through the direction control valves 23 and 24 change according to the operation of the left traveling operation lever 27 and the right traveling operation lever 26.

Between each of the directional control valves 23 and 24 and the traveling hydraulic motors 25 and 26, a pressure oil supply pipe 51 (51A, 51A,
1B) and 52 (52A, 52B) are provided, respectively. 25A and 26A are forward pressure oil inflow ports of the hydraulic motors 25 and 26, and 25B and 26B are hydraulic motor 2
5, 26 are reverse pressure oil inflow ports.

The pressure oil discharge ports 1b and 1c of the hydraulic pump 1 and the direction control valves 23 and 24 are connected by pressure oil supply pipes 21 and 22, respectively. And the pressure oil supply line 21,
Variable throttle valves 31, 32 that can bypass the pressure oils P 1, P 2 on the pipelines 21, 22 and adjust the flow rate of the bypassed pressure oil are provided in the middle of the position 22 and close to the hydraulic pump 1. Each is provided.

That is, the bypass line 33 is branched from the left traveling pressure oil supply line 21. The throttle valve 31 is provided on the bypass pipe 33. The pressure oil that has passed through the throttle valve 31 is further returned to the pump suction port 13 via the return line 35.

Similarly, a bypass line 34 branches off from the right traveling pressure oil supply line 22. This bypass line 3
A throttle valve 32 is provided on 4. The pressure oil that has passed through the throttle valve 32 is further returned to the pump suction port 13 via the return line 36.

The pressure oil that has passed through the throttle valves 31 and 32 may be discharged to a tank.

The gear pump 3 is a constant displacement type hydraulic pump, and is a pressure oil supply source for supplying pressure oil to, for example, a turning hydraulic motor via the gear pump discharge port 10. The gear pump 3 is driven by the engine 2 like the hydraulic pump 1.

The pressure oil supply pipes 41 and 42 are pipes for supplying the pressure oil discharged from the hydraulic pump 1 to the swash plate drive mechanism 16. The pressure oil supply lines 41 and 42 include branch lines 4a to 4
f is provided.

The pressure reducing valve 5 is a valve for reducing the pressure oil flowing through the pipe 41. Further, the pressure reducing valve 5 causes the pressure oil that has been reduced in pressure to flow out to the pipe 42.

The swash plate drive mechanism 16 includes a servo piston 17 for driving the swash plate 1a of the hydraulic pump 1 and a control pressure oil acting on the large-diameter side (left side) of the servo piston 17.
PC for applying control pressure oil to the S valve (load sensing valve) 18 and the large-diameter chamber (left side) of the servo piston 17.
And a valve 19.

The PC valve 19 is connected to each discharge port 1 of the hydraulic pump 1.
The control valve controls the swash plate 1a of the variable displacement hydraulic pump 1 so that the product of the average pressure of the pressure oils P1 and P2 of b and 1c and the displacement volume of the hydraulic pump 1 does not exceed a certain torque. If the rotation speed of the engine 2 is constant, the tilt angle of the swash plate 1a of the hydraulic pump 1 is set so that the product of the average pressure and the discharge flow rate of the pump 1 does not exceed a certain horsepower (the maximum horsepower of the engine 2). Controlled.

The LS valve 18 is connected to the hydraulic motors 25, 26
And a control valve for controlling the tilt angle of the swash plate 1a of the hydraulic pump 1 according to the load pressure of each hydraulic actuator. LS
The valve 18 performs control as follows. That is, the discharge pressure of the hydraulic pump 1 obtained through the pump pressure input port 14 is always set to be equal to or smaller than the LS pressure which is the maximum value of the load pressures of the plurality of hydraulic actuators obtained through the LS pressure input port 15 by the set differential pressure. Control to increase (load sensing control).

Next, the operation of the hydraulic circuit shown in FIG. 1 will be described. Note that the description about the fact that the pressure oil discharged from the hydraulic pump 1 flows into the swash plate drive mechanism 16 via the pipelines 4a, 4b, 41, 42, 4c, 4d, and 4f will be given. The description related to the control of the swash plate 1a of the hydraulic pump 1 is a known technique, and is different from the gist of the present invention, so the description is omitted.

The hydraulic pump 1 sucks pressure oil in a tank (not shown) from a pump suction port 13 and discharges pressure oil P1 from a pressure oil discharge port 1a.
1. Directional control valve 23, pressure oil supply line 51 (51A, 51
B) to the hydraulic motor 25 for left traveling. The pressure oil P2 is discharged from the pressure oil discharge port 1b, and the pressure oil P2 is discharged from the pressure oil supply line 22, the directional control valve 24, and the pressure oil supply line 52.
(52A, 52B) to the other right traveling hydraulic motor 26.

When the directional control valve 23 is switched to the forward position by the operator operating the left traveling operation lever 27 to the forward side, the discharge pressure oil P1 of the hydraulic pump 1 is supplied to the forward pressure oil supply. The fluid passes through the pipe 51A and flows into the forward pressure oil inflow port 25A of the hydraulic motor 25. As a result, the hydraulic motor 25 rotates in the forward direction, and the left crawler belt 83 rotates in the forward direction.
The pressure oil flowing out from the opposite port 25B of the hydraulic motor 25 passes through the pipe 51B and the direction control valve 23, and is returned to the tank 29.

Similarly, when the operator operates the right traveling operation lever 28 to the forward side to switch the direction control valve 24 to the forward position, the discharge pressure oil P2 of the hydraulic pump 1 is supplied to the forward pressure oil supply line 52A. And flows into the forward pressure oil inflow port 26A of the hydraulic motor 26. As a result, the hydraulic motor 26 rotates in the normal rotation direction, and the right crawler belt 84 rotates in the forward direction. The pressure oil flowing out of the opposite port 26B of the hydraulic motor 26 passes through the pipe 52B and the directional control valve 24 and is returned to the tank 30.

When the operator now operates the left traveling operation lever 27 to the reverse side to switch the direction control valve 23 to the reverse position, the discharge pressure oil P1 of the hydraulic pump 1 is supplied to the reverse pressure oil supply. After passing through the pipe 51B, the hydraulic motor 25 flows into the reverse pressure oil inflow port 25B. As a result, the hydraulic motor 25 rotates in the reverse direction, and the left crawler belt 83 rotates in the reverse direction.
The pressure oil flowing out of the opposite port 25A of the hydraulic motor 25 is returned to the tank 29 through the pipe 51A and the direction control valve 23.

Similarly, when the operator operates the right traveling operation lever 28 to the reverse side to switch the direction control valve 24 to the reverse position, the discharge pressure oil P2 of the hydraulic pump 1 is discharged to the reverse pressure oil supply line 52B. , And flows into the reverse pressure oil inflow port 26B of the hydraulic motor 26. As a result, the hydraulic motor 26 rotates in the reverse direction, and the right crawler belt 84 rotates in the reverse direction. The pressure oil flowing out from the opposite port 26A of the hydraulic motor 26 is returned to the tank 30 through the pipeline 52A and the directional control valve 24.

In the drawing, the tank 2 is provided for convenience of explanation.
Although 9 and 30 are shown separately, the same tank is used in an actual apparatus.

As described above, the excavator 80 moves straight forward or backward. It is necessary to operate the operation levers 27 and 28 in the same direction and the same operation amount in order to make the hydraulic excavator 80 go straight.

Here, if a running curve occurs during straight traveling, the operator adjusts the opening areas of the left and right throttle valves 31 and 32 to adjust the bypass flow rate. As a result, the pressure oils P1 and P2 flowing through the pressure oil supply line 21 for the left traveling and the pressure oil supply line 22 for the right traveling are respectively bypassed by the predetermined amount in the bypass lines 33 and 34, and the return line 35 , 36 to the pump suction port 13 respectively. Therefore, the flow rate difference between the pressure oils P1 and P2 flowing through the left and right pressure oil supply pipes 21 and 22 is corrected, and the traveling bend of the hydraulic shovel 80 when traveling straight is corrected. The pressure oil bypassed to the bypass pipes 33 and 34 may be directly returned to the tank.

As described above, the hydraulic pump 1 is disposed close to the engine 2. For this reason, the position from the position of the engine hood 85 to the hydraulic pump 1 is very close, and the operator can easily reach (see FIG. 2).

Therefore, the throttle valves 31 and 32 provided close to the hydraulic pump 1 can be adjusted very easily from the position of the engine hood 85.

Therefore, it is possible to easily adjust the throttle valves 31 and 32 with good workability according to the running bending of each vehicle after the production and assembly of the excavator 80 or during actual running by the user.

FIG. 3 shows an example of a configuration in which throttle valves 31 and 32 are provided in the casing 100 of the hydraulic pump 1.

FIG. 3 (a) is a front view of the hydraulic pump 1, and FIG. 3 (b) shows an arrow Z in FIG. 3 (a). Thus, the throttle valves 31, 32 are provided in the casing 100 of the hydraulic pump 1.
Is arranged, the throttle valves 31 and 32 can be more easily adjusted from the position of the engine hood 85.

Next, a specific configuration of the throttle valves 31 and 32 will be described below. Note that the throttle valve 31 provided for the left traveling will be described as a representative. As shown in FIG. 1, pressure oil flows into the throttle valve 31 from a pressure oil inflow port 33a, and pressure oil flows out from a pressure oil outflow port 33b.

FIG. 4 shows the structure of the throttle valve 31 provided on the casing 100 of the hydraulic pump 1 as described with reference to FIG. The throttle valve 31 includes a valve body 60 and an insertion member 62. The insertion member 62 further includes a clearance filter 69.
And a fixed throttle portion 70, a notch portion 68, and a tapered portion 67. The upstream position of the clearance filter 69 is the pressure oil inflow port 33a. The downstream position of the tapered portion 67 is the pressure oil outflow port 33b.

That is, as shown in FIG. 4, the throttle valve 31 includes the pump casing 100 as a valve main body, the valve main body 60, and an insertion member 62 that can be freely inserted into the valve main body 60. ing.

FIG. 5 shows a part of the throttle valve 31 in an enlarged manner. FIG. 5A is an enlarged view of a tip portion of the throttle valve 31 of FIG. FIG. 5B shows a BB cross section of FIG. 5A. FIG. 5C shows the variable aperture section of FIG. 5A further enlarged. FIG. 5D shows a C-view of FIG. 5A.

The structure of the throttle valve 31 will be described with reference to these drawings.

When the insertion member 62 is inserted into the valve body 60 in the longitudinal direction, a clearance filter 69 is formed at the distal end in the insertion direction. The clearance filter is a member having a function of a filter for removing foreign matter in the pressure oil by a gap (clearance).

A fixed throttle 70 is formed downstream of the clearance filter 69.

The fixed throttle portion 70 is a cylindrical portion formed over the entire outer periphery of the insertion member 62. The diameter of this cylindrical portion is smaller than the diameter of the bypass pipe 33 in the pressure oil inflow port 33a. The fixed throttle portion 70 allows the pressure oil P1 to pass with a certain opening area.

Further, a notch 68 is formed downstream of the fixed throttle 70.

As shown in FIG. 5B, the cutout portion 68 is formed at a part of the periphery of the outer periphery of the insertion member 62, that is, at two places. The notch shape is, for example, a V-shaped groove. The notch 68 formed in a part of the periphery of the insertion member 62 allows the pressure oil P1 to pass through with a very small opening area. The flow rate of the pressure oil P1 passing through the notch portion 68 changes according to the insertion position of the insertion member 62. The opening area of the notch 68 is extremely small as compared with the total cross-sectional area of the gap d of the clearance filter 69.

Further, a tapered portion 67 is formed downstream of the notch 68. A tapered portion is also formed on the valve body 60 side corresponding to the tapered portion 67 on the insertion member 62 side. The tapered portion 67 is formed over the entire outer periphery of the insertion member 62. Therefore, the passage opening area of the pressure oil P1 is changed according to the change in the relative position between the tapered portion 67 on the insertion member 62 side and the tapered portion on the valve body 60 side. That is, an orifice is formed by the tapered portion 67 on the insertion member 62 side and the tapered portion on the valve body 60 side.

As shown in FIG. 5C, the inclination is different between the tapered portion 67 on the insertion member 62 side and the tapered portion on the valve body 60 side. The inclination angle of the tapered portion 67 on the insertion member 62 side is larger than the inclination angle of the tapered portion on the valve body 60 side. Therefore, when the throttle amount of the throttle valve 31 is the maximum (zero flow rate of the pressure oil P1), the tapered portion 67 comes into line contact with the tapered portion on the valve body 60 side along the circumferential direction. As a result, the flow rate of the pressurized oil P1 can be made extremely accurate to zero without causing bleeding or leakage of the pressurized oil P1 from the tapered portion 67 to the downstream side. The above-described notch portion 68 and tapered portion 67 constitute a variable throttle portion 71.

The return pipe 3 is further downstream of the tapered portion 67.
5 communicates with the pump suction port 13.

[0095] The O-
A ring 66 is provided over the entire outer periphery of the insertion member 62 to prevent the pressure oil P1 from leaking or leaking to the outside from between the insertion member 62 and the valve body 60.

[0096] At a position further behind the place where the O-ring 66 is provided, a screw portion 65 is formed which is screwed to the valve body 60.

A hexagonal bolt hole 63 is formed at the rear end of the portion further behind the screw portion 65. On the outer periphery of the rear end of the insertion member 62, a threaded portion to be screwed to the lock nut 64 is formed.

The operation of adjusting the bypass flow rate of the pressure oil P1 using the throttle valve 31 will be described below.

An operator inserts a hexagon wrench into the hexagon bolt hole 6
3 and rotate clockwise, screw part 65
The insertion member 62 is inserted in the direction of the arrow A1 while screwing with the valve body 60. The state where the insertion member 62 is inserted to the innermost position is as shown in FIG. At this time, the tapered portion 67 makes linear contact with the valve body 60 along the circumferential direction, and the opening area of the tapered portion 67 through which the pressure oil P1 passes becomes zero. At this time, the throttle amount of the throttle valve 31 becomes the maximum (zero flow rate of the pressure oil P1), and the bypass flow rate to the pressure oil outflow port 33b becomes zero.

When the operator rotates the hex wrench in the counterclockwise direction from the state of the bypass flow rate of zero (the maximum throttle amount), the insertion member 62 is screwed into the valve body 60 while the screw 65 is screwed into the valve body 60. It is moved in the direction A2 to escape from 60.

As the insertion member 62 moves in the direction of arrow A2, the bypass flow rate to the pressure oil outflow port 33b increases.

That is, the insertion member 62 for the valve body 60
When the insertion position is moved in the direction of arrow A1 or A2, the opening area between the valve body 60 and the variable throttle portion 71 including the tapered portion 67 and the notch 68 changes. As a result, by adjusting the insertion position of the insertion member 62, the flow rate (bypass flow rate) of the pressure oil guided from the pressure oil inflow port 33a to the pressure oil outflow port 33b is adjusted.

At the point where the insertion position is optimal, the locking nut 64 is screwed into the rear end of the insertion member 62. The insertion member 62 is fixed to the valve main body 60 by bringing the lock nut 64 into contact with the wall surface 61 of the pump casing 100.

Next, the operation and effect of the throttle valve 31 will be described.

On the upstream side of the pressurized oil of the tapered portion 67 of the insertion member 62, a notch 6 through which the pressurized oil P1 passes with a very small opening area is provided in a part around the outer periphery of the insertion member 62.
8 are provided. For this reason, the change in the bypass flow rate of the pressure oil P1 is reduced with respect to the screwing rotation amount of the insertion member 62.

Here, comparison with a conventional throttle valve will be made. In the conventional throttle valve, only a fixed throttle portion formed over the entire outer circumference of the insertion member 62 is provided upstream of the tapered portion 67 of the insertion member 62. Therefore, the insertion member 62
The opening area of the tapered portion 67 changes greatly with respect to the slight screw-in rotation amount, and the bypass flow rate of the pressure oil P1 greatly changes. That is, the sensitivity of the flow rate change to the screwing amount is high.

Here, when the insertion member 62 is fixed to the valve body 60 using the locking nut 64, the locking nut 64 is fixed.
Before and after tightening, the amount of screwing rotation of the insertion member 62 may change due to the co-rotation of the insertion member 62.

In the conventional throttle valve, a change in the bypass flow rate of the pressure oil P1 is large with respect to a change in the screwing rotation amount of the insertion member 62. For this reason, at the time of fixing with the locking nut 64, an extremely large deviation occurs with respect to the bypass flow rate adjusted as the optimum one. For this reason, it is not easy to accurately adjust the throttle valve.

On the other hand, in the throttle valve 31 of the present embodiment, the change in the bypass flow rate of the pressure oil P1 is extremely small with respect to the change in the screwing rotation amount of the insertion member 62.

That is, as shown in FIG. 5D, the notch 68 is formed in the V-shaped portion 68 along the insertion direction of the insertion member 62.
a and a parallel portion 68b. In the V-shaped portion 68a, the opening area gradually increases with respect to the amount of screw rotation of the insertion member 62, and in the parallel portion 68b, the opening area becomes constant. Therefore, the change in the opening area of the notch 68 becomes extremely gentle with respect to the amount of rotation of the insertion member 62 when screwed. The amount of change in the opening area of the notch 68 is much smaller than the amount of change in the opening area of the taper 67. Therefore, the sensitivity of the flow rate change to the screwing amount is low.

For this reason, for example, before and after the locking nut 64 is tightened, the insertion member 62 is rotated by the co-rotation of the insertion member 62.
Even if the screwing rotation amount of the second screw 2 slightly changes, only a slight deviation from the optimally adjusted bypass flow rate occurs. Therefore, according to the throttle valve 31 of the present embodiment, the displacement of the screwing amount of the insertion member 62 when the locking nut 64 is fixed is allowed, and the adjustment of the throttle valve 31 can be easily performed with high accuracy.

Although the notches 68 are provided at two places on the outer periphery of the insertion member 62 as shown in FIG. 5B, a greater number may be provided.
In some cases, only one location is required. For example, as shown by the broken lines, the notches 68 can be provided at equal intervals at four places. By the way, the notch 68 is inserted into the insertion member 62.
Are formed with a very small opening area on a part of the outer periphery of the. For this reason, the pressure oil P1 is notched 68 from the upstream side.
And foreign matter such as dust existing in the pressure oil P1 reaches the notch 6
8, the sensitivity of the flow rate change to the screwing amount is greatly changed.

For this reason, it is necessary to prevent foreign matter from entering the notch 68.

In this respect, in the present embodiment, a clearance filter 69 having a gap d that does not allow foreign matter to pass therethrough is provided over the entire periphery of the insertion member 62 on the upstream side of the notch 68.

That is, the tip of the clearance filter 69 communicates with the pressure oil discharge port 1 b, and the pressure oil P 1 flows into the clearance filter 69 via the bypass pipe 33. The clearance filter 69 is an annular member. Therefore, a clearance (clearance) d is provided between the insertion member 62 and the valve body 60 by the clearance filter 69 over the entire circumference of the insertion member 62 such that foreign matter such as dust in the flowing pressure oil P1 does not pass. .

The clearance filter 69 includes the insertion member 6
2 is formed over the entire circumference of the clearance filter 69, even if foreign matter is blocked by a part of the outer circumference of the clearance filter 69,
The pressure oil P1 can pass downstream through another part. Therefore, it is possible to prevent foreign matter from being mixed into the pressure oil P1 that has passed through the clearance filter 69,
It is possible to avoid a situation in which foreign matter such as dust existing in the pressure oil P1 enters the notch portion 68.

As described above, according to the throttle valve 31 of the present embodiment, it is possible to allow a shift in the amount of screwing of the spool when the locking nut 64 is fixed, and to easily and accurately adjust the throttle valve 31. . Further, the problem associated with the improvement of the easiness, that is, the problem of easiness of clogging of foreign matters can be solved at the same time.

Next, a preferred embodiment of a hydraulic excavator 80 having different running bends when traveling forward and when traveling backward will be described.

FIG. 6 is a hydraulic circuit diagram showing the arrangement of the throttle valve according to this embodiment. Note that circuit portions common to FIG. 1 are omitted. Only the parts different from FIG. 1 are shown.

As shown in FIG. 6, in this embodiment,
A throttle valve for bypassing the pressure oil on the pipeline and adjusting the flow rate of the bypassed hydraulic oil in the middle of the forward pressure oil supply pipeline (51A, 52A) and the reverse pressure oil supply pipeline (51B, 52B). (31A, 32A), (31B, 3
2B) is provided.

The operation for correcting a running curve will be described below.

When the vehicle travels in a forward direction, if the vehicle bends when traveling straight ahead, the operator can change the left and right variable throttle valves 31A provided for forward use.
Adjust 32A. As a result, the forward pressure oil supply line 51
A and 52A are respectively returned to the tanks 72 and 74 after being bypassed by a predetermined flow rate. For this reason, the flow rate difference of the pressure oil flowing through the left and right pressure oil supply pipelines 51A and 52A is corrected, and the traveling bend of the hydraulic shovel 80 during forward movement is corrected.

On the other hand, when the vehicle runs in a straight line in the reverse direction, the operator turns the left and right variable throttle valves 31 provided for the reverse direction.
Adjust B and 32B. As a result, the reverse pressure oil supply line 5
The pressurized oil flowing through 1B and 52B is returned to the tanks 73 and 75 by a predetermined flow rate, respectively. For this reason, the flow rate difference between the hydraulic oil flowing through the left and right hydraulic oil supply pipes 51B and 52B is corrected, and the traveling bend of the hydraulic shovel 80 during backward movement is corrected.

As described above, according to the present embodiment, the throttle valve (31B, 31B, 31B, 31B, 31A, 31A, 31A, 31A) is separately provided when correcting the running curve when moving forward and when correcting the running curve when moving backward. 32B) is used for 32A. In other words, even when the traveling bend is different between forward traveling and reverse traveling, the traveling bend is corrected individually.

Therefore, according to the present embodiment, the running curve can be corrected more accurately both in the forward direction and in the reverse direction as compared with the conventional one described in Japanese Utility Model Publication No. Hei 8-9236. .

FIG. 7 shows a modification of the hydraulic circuit shown in FIG.

That is, in FIG. 6, the left and right hydraulic motors 25,
26, each pressure oil discharge port 1 of the hydraulic pump 1
b, 1c, and different pressure oil discharge ports 1b, 1b
The pressure oils P1 and P2 discharged from c are individually driven. On the other hand, in the hydraulic circuit shown in FIG. 7, the left and right hydraulic motors 25 and 26 are provided with a single pressure oil discharge port 1d of the hydraulic pump 1 and are discharged from the same pressure oil discharge port 1d. Driven by pressure oil.

FIG. 8 shows an example of a hydraulic circuit configuration having the same operation and effect as the hydraulic circuit shown in FIG. In FIG. 8, only the hydraulic circuit for left traveling is shown, and the hydraulic circuit for right traveling is omitted.

As shown in FIG. 8, in this embodiment,
Pressure oil supply line 51A for forward and pressure oil supply line 5 for reverse
1B, throttle valves 31 for bypassing the pressure oil on the pipeline and adjusting the flow rate of the bypassed pressure oil, respectively.
A, 32A are provided. However, unlike the hydraulic circuit of FIG. 6, the throttle valves 31A and 31B are provided on conduits 53 and 54 that connect one port 25A and the other port 25B of the hydraulic motor 25, respectively. Therefore, a check valve 55 is provided on the communication pipe 53 so that only the pressure oil flowing through the pressure oil supply pipe 51A passes and the pressure oil on the opposite pressure oil supply pipe 51B does not pass. Similarly, a check valve 56 is provided on the communication pipe 54 so that only the pressure oil flowing through the pressure oil supply pipe 51B passes and the pressure oil on the opposite pressure oil supply pipe 51A does not pass.

[0130] The operation for correcting the running curve will be described below.

[0131] When the vehicle travels straight ahead in the forward direction, the operator adjusts the variable throttle valve 31A provided for forward use. As a result, the pressure oil flowing through the forward pressure oil supply pipe 51A is bypassed by a predetermined flow rate to the communication pipe 53 and returned to the return pipe via the check valve 55. Similarly, the bypass flow rate of the right pressure oil supply pipe 52A is adjusted. For this reason, the flow rate difference of the pressure oil flowing through the left and right pressure oil supply pipelines 51A and 52A is corrected, and the traveling bend of the hydraulic shovel 80 during forward movement is corrected.

[0132] On the other hand, when the vehicle travels in a reverse direction and the vehicle is running straight, the operator adjusts the variable throttle valve 31B provided for reverse travel. As a result, the pressure oil flowing through the reverse pressure oil supply pipe 51B is bypassed by a predetermined flow rate to the communication pipe 54 and returned to the return pipe via the check valve 56. Similarly, the bypass flow rate of the right pressure oil supply pipe 52B is adjusted. Therefore, the left and right pressure oil supply pipes 51B, 52B
The difference in the flow rate of the pressure oil flowing through the hydraulic shovel 80 is corrected, and the traveling curve of the hydraulic shovel 80 during backward movement is corrected.

As described above, also in the embodiment shown in FIG. 8, when the traveling bend during forward traveling is corrected and when the traveling bend during backward traveling is compensated, the throttle valve (31A provided separately) is provided. 32B) is used for each of 31B and 32A. In other words, even when the traveling bend is different between forward traveling and reverse traveling, the traveling bend is corrected individually.

Therefore, according to the present embodiment, the running curve can be corrected more accurately in both forward and backward travels than in the conventional Japanese Utility Model Publication No. Hei 8-9236. . In the case of the embodiment shown in FIGS. 6, 7, and 8, the throttle valves 31 (31A, 31B), 32 (32
A, 32B) may be arranged on the directional control valves 23, 24 themselves. Also, the throttle valves 31 (31A, 31B), 32 (32
A, 32B) may be disposed on the hydraulic motors 25, 26 themselves.

The hydraulic circuit according to the present embodiment can be applied to any hydraulically driven traveling body including construction machines. Note that the throttle valves 31 and 32 are not limited to the structure described in the present embodiment, and a flow control valve having a conventional general structure such as an orifice and a choke can be used.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of a traveling bending correction device for a hydraulically driven traveling body according to the present invention.

FIG. 2 is a perspective view showing a structure of a hydraulic shovel assumed in the embodiment.

FIGS. 3A and 3B are diagrams showing a state in which a throttle valve is provided in a hydraulic pump, wherein FIG. 3A is a front view, and FIG.
It is an arrow Z view of (a).

FIG. 4 is a diagram showing the entire structure of the throttle valve of the embodiment.

5 is an enlarged view of a part of the throttle valve shown in FIG. 4, FIG. 5 (a) is an enlarged view of a tip of a spool, and FIG. 5 (b) is an enlarged view of FIG. a) BB sectional view, FIG. 5
FIG. 5C is a view showing the tapered portion of FIG. 5A further enlarged, and FIG. 5D is a C view of FIG. 5A.

FIG. 6 is a hydraulic circuit diagram showing a state in which a throttle valve is arranged at a position different from the hydraulic circuit of FIG. 1;

FIG. 7 is a hydraulic circuit diagram showing a modified example of the hydraulic circuit shown in FIG. 6, and is a diagram showing an example of a hydraulic circuit configuration using a single hydraulic pump.

FIG. 8 is a diagram showing another configuration example of the hydraulic circuit having the same operation and effect as the hydraulic circuit of FIG. 6;

FIG. 9 is a hydraulic circuit diagram showing an arrangement of a conventional throttle valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic pump 1a Swash plate 1b, 1c, 1d Pressure oil discharge port 2 Engine 21, 22, 51, 52 Pressure oil supply line 23, 24 Direction control valve 25, 26 Hydraulic motor 31, 32 Throttle valve

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2D003 AA01 AB01 AB05 BA02 BB02 CA03 CA09 DA02 3D052 AA01 AA16 BB01 BB08 DD01 EE01 EE02 FF02 GG02 HH02 JJ00 JJ21 JJ22 JJ25 3G093 AA10 AA15 EB00 ABA12 BB00 CC DB13 DB46 DB49 DB54 EE17 GG02 JJ02

Claims (3)

[Claims] 1. Left and right hydraulic actuators respectively provided for left and right crawler tracks (83, 84) or wheels of a hydraulically driven traveling body (80) for driving these left and right crawler tracks (83, 84) or wheels, respectively. (25, 26)
And a hydraulic pump (1) driven by the engine (2) and provided in proximity to the engine (2); and a hydraulic pump (1) provided corresponding to the left and right hydraulic actuators (25, 26). 1) and the left and right hydraulic actuators (2)
5 and 26), and controls the direction of the flow of the hydraulic oil discharged from the hydraulic oil discharge ports (1b, 1c) of the hydraulic pump (1) to control the left and right hydraulic actuators (25, 26). ), Wherein the hydraulically driven traveling body (80), which is provided with each of the directional control valves (23, 24) for supplying pressure oil to the hydraulically driven traveling body (80), corrects the traveling curvature of the hydraulically driven traveling body (80) when traveling straight ahead. A hydraulic oil supply line (2) between the hydraulic oil discharge ports (1b, 1c) of the hydraulic pump (1) and the direction control valves (23, 24).
1, and 22) at a position close to the hydraulic pump (1) at a position close to the hydraulic pump (1).
A travel bending correction device for a hydraulically driven traveling body, wherein a throttle valve (31, 32) is provided which bypasses P2) and can adjust the flow rate of pressure oil to be bypassed. 2. The travel bending correction device for a hydraulically driven traveling body according to claim 1, wherein said throttle valves (31, 32) are disposed in said hydraulic pump (1). 3. Left and right hydraulic actuators are provided corresponding to the left and right crawler tracks (83, 84) or wheels of the hydraulically driven traveling body (80), and drive the left and right crawler tracks (83, 84) or wheels, respectively. (25, 26)
And the hydraulic actuators (25, 26) are provided corresponding to the left and right hydraulic actuators (25, 26), respectively, and control the flow direction of the hydraulic oil discharged from the hydraulic pump (1) to the left and right hydraulic actuators (25, 26), respectively. Each directional control valve (23, 24) for supplying pressurized oil, and the directional control valve (23, 24)
And the hydraulic actuators (25, 26). The hydraulic oil pressure ports (25A, 26A) and the reverse hydraulic oil inlet ports (25B, 26B) of the hydraulic actuators (25, 26) have a pressure. A hydraulically driven traveling body (8) having a forward pressure oil supply line (51A, 52A) and a reverse pressure oil supply line (51B, 52B) for supplying oil.
0) In the travel bending correction device for a hydraulically driven traveling body that corrects the travel bending during straight running, the forward pressure oil supply pipe (51A, 52A) and the reverse pressure oil supply pipe (51B, 52B). The throttle valve ((31A, 32A), which can bypass the pressure oil on the pipeline and adjust the flow rate of the bypassed pressure oil,
A) A traveling bending correction device for a hydraulically driven traveling body, provided with (31B, 32B).