JPH06167037A - Hydraulic circuit for crawler type vehicle - Google Patents

Abstract

PURPOSE:To secure the traveling action which is not influenced by the difference of the load pressure between a traveling motor and an actuator for a working device and the difference of the load pressure between the left and right traveling motors. CONSTITUTION:In the discharge conduits 13a and 14a of pumps 13 and 14, a priority selector valve 17 for leading the pump discharged oil to the traveling control valves 15L and 15R when the traveling operation is executed is installed, and a traveling priority valve 21 equipped with the pressure compensation is installed in a conduit 18 connecting the priority selector valve 17 and the traveling control valves 15L and 15R. In the simultaneous operation of the traveling control valves 15L and 15R and work control valve 16, the oil in a set flow rate is supplied to the traveling control valves 15L and 15R by the automatic flow rate setting action of the traveling priority valve 21, and the rest quantity is supplied to the work control valve 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for a crawler type vehicle such as a hydraulic excavator which is driven by a left and right crawler driven by a traveling motor.

[0002]

2. Description of the Related Art A conventional circuit will be described by taking a hydraulic circuit of a hydraulic excavator as an example.

FIG. 4 shows a general hydraulic circuit configuration of a hydraulic excavator.

In the hydraulic excavator, left and right traveling motors 1L and 1R that drive left and right crawlers are used as actuators driven by pumps, and a plurality of actuators for working devices other than these traveling motors (in order to avoid complication in the figure, (Only two cylinders are shown) 2 ...

Each of these actuators is divided into a first actuator group A1 including a left traveling motor 1L and a second actuator group A2 including a right traveling motor 1R. The first actuator group A1 is divided by a first pump 3 into a first actuator group A1. Two
The actuator groups A2 are each driven by the second pump 4.

Further, these actuator groups A1 and A2
The control valve group for controlling the first control valve block B1 including a left travel motor control valve (left travel control valve) 5L and a work device control valve (work control valve) 6 is also arranged in accordance with the actuator. , Control valve for right traction motor (right traction control valve)
Second control valve block B consisting of 5R and another work control valve 6
In both control valve blocks B1 and B2, the travel control valves 5L and 5R and the work control valve 6 are connected in parallel.

In this way, the left and right traveling motors 1L and 1R are driven by the separate pumps 3 and 4, and the traveling motors 1L and 1R in both actuator groups A1 and A2.
And pumps 3 and 4 for which the working device actuator 2 is common
Is configured to be driven by.

[0008]

However, this configuration has the following drawbacks.

Both first and second control valve blocks B1, B
2, when the travel control valves 5L, 5R and the work control valve 6 are simultaneously operated, the pump discharge oil causes the travel motor 1L,
1R and the working device actuator 2 are diverted.

In this case, the diversion ratio is determined by the load pressure (size of load) of the working device actuator 2,
This load pressure changes frequently during work due to changes in soil quality. Therefore, during traveling, the traveling motor 1
The rotation speeds of L and 1R fluctuate.

When traveling straight ahead, the left and right traveling motors 1
There is a difference in the amount of inflowing oil (speed difference) between L and 1R, which prevents straight running.

On the other hand, in order to solve such a problem,
As disclosed in JP-A-1-126407,
When operating the travel control valve and the work control valve simultaneously, the circuit is switched so that the discharge oil of one pump is supplied to the left and right travel motors in parallel, and the discharge oil of the other pump is supplied to the actuator for the work device. What was done was proposed.

However, even with this configuration, when a large difference occurs in the resistance of the running road surfaces of the left and right crawlers, this causes a difference in load pressure, which causes a speed difference between the left and right running motors, making straight running difficult. There was a problem of becoming.

Further, according to both the conventional techniques, the operation amount and speed of the travel control valve and the work control valve do not correspond exactly to each other. Therefore, when it is desired to have a constant relationship between the travel speed and the work speed (hereinafter, There is a drawback that the operation becomes difficult).

Therefore, according to the present invention, a stable traveling action can be obtained which is not affected by the difference in load pressure between the traveling motor and the working device actuator, and the difference in load pressure between the left and right traveling motors, and the tuning operation can be easily performed. A hydraulic circuit of a crawler type vehicle capable of performing the above is provided.

[0016]

According to a first aspect of the present invention, there are provided left and right traveling motors for driving the left and right crawlers, and a plurality of working device actuators other than the traveling motors.
In a crawler type vehicle in which these are divided into a first actuator group including a left traveling motor and a second actuator group including a right traveling motor, and the first and second actuator groups are driven by separate pumps, A travel control valve that controls the travel motors of the first and second actuator groups, a work control valve that controls the working device actuators of both actuator groups, and a travel operation that detects that the travel control valve has been operated. Detection means, work operation detection means for detecting that the work device actuator has been operated, a priority switching valve provided in the discharge conduit of the pump, and an outlet side conduit of the priority switching valve A travel priority valve with pressure compensation, which operates based on signals from the travel operation detection means and the work operation detection means, The valve has a working position and a travel position,
Based on the traveling operation detection signal from the traveling operation detecting means, the working position is switched to the traveling position, and the pump discharge oil at the traveling position is led to the traveling priority valve. At the working position, the pump discharge oil is entirely delivered at the work position. It is configured to lead to a control valve, the travel priority valve, based on a travel operation detection signal from the travel operation detection means and a work operation detection signal from the work operation detection means, to the travel control valve, The pump discharge oil of a set flow rate is supplied, and the remaining amount is supplied to the work control valve.

According to a second aspect of the present invention, in the structure of the first aspect, the work operation detecting means is replaced by a secondary pressure variable type pilot valve, and the travel priority valve is a secondary pressure of the pilot valve and travel. Based on a traveling operation detection signal from the operation detecting means, a pump discharge oil of a set flow rate is supplied to the traveling control valve, and the remaining amount is supplied to the work control valve.

[0018]

With the above structure, when the travel control valve and the work control valve are simultaneously operated, the priority switching valve is switched to the travel position, and the pump discharge oil passes through the travel priority valve to the travel control valve side and the work control valve side. Divert to.

In this case, depending on the operation amount of the work control valve (command pressure by the pilot valve in the case of claim 2) and the operation amount of the travel control valve, the travel control valve is operated by the automatic flow rate setting action of the travel priority valve. A fixed amount of oil is supplied, and the remaining oil is supplied to the work control valve.

That is, the amount of oil proportional to the amount of operation of the travel control valve is supplied to the travel motor irrespective of fluctuations in the load pressure of the working device actuator.

Further, the left and right traveling motors are driven by separate pumps, and their load pressures do not affect each other.

Therefore, there is no fluctuation in the traveling speed, and the straightness is secured.

Further, since the operation amount and the speed on the traveling control valve side and the work control valve side are accurately proportional to each other during the simultaneous operation, the traveling speed and the working speed can be easily synchronized.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS.

First Embodiment (See FIG. 1) C1 is a first actuator group consisting of a left traveling motor 11L and a working device actuator 12, and C2 is a second actuator consisting of a right traveling motor 11R and a working device actuator 12. Group, 13 is the first actuator group C
The first pump drives 1 and the second pump drives the second actuator group C2.

D1 is a first control valve block, D2 is a second control valve block, and the first control valve block D1 works with the left travel control valve 15L for controlling the left travel motor 11L of the first actuator group C1. And a work control valve 16 that controls the actuator 12 for work, and the second control valve block D2 controls the right travel control valve 15R that controls the right travel motor 11R of the second actuator group C2 and the work that controls the work actuator 12. And the control valve 16.

A hydraulic pilot type switching valve is used for the traveling control valves 15L and 15R and the work control valve 16.

The discharge lines 13a and 14a of the first and second pumps 13 and 14 are connected to the running-side lines 18 connected to the left and right running control valves 15L and 15R via a hydraulic pilot type priority switching valve 17. 18, and work control valves 16, 16
Is connected to the work-side pipelines 19, 19.

The priority switching valve 17 has a working position a and a traveling position b.
In the state where the pilot pressure is not introduced, the pump discharge oil is in the working position a as shown in the drawing, and the entire amount of pump discharge oil is supplied to the working side conduits 19 and 19 of the control valve blocks D1 and D2 (work control valve 16, 16).

On the other hand, when at least one of the left and right traveling control valves 15L, 15R is operated (pilot pressure is introduced), the highest pilot pressure is given priority via the traveling operation detection circuit (high pressure selection circuit) 20. It is introduced into the pilot chamber of the switching valve 17. As a result, the switching valve 17 is switched to the traveling position b, and all the pump discharge oil is discharged to the traveling side pipeline 1.
8 and 18 (travel control valves 15L and 15R).

Further, on the traveling side pipes 18, 18, traveling priority valves (so-called priority valves) 21, 21 which are hydraulic pilot type flow control valves with pressure compensation are provided.

Of the pilot chambers on both sides of the travel priority valves 21 and 21, the pilot chamber on the side opposing the spring 22 has the highest pilot pressure of the pilot pressures introduced to the work control valves 16 and 16. The pressure is introduced through the work operation detection circuit (high pressure selection circuit) 23, and in parallel with this, the inlet side pressure of the throttle 24 provided inside the travel control valves 15L and 15R is introduced.

In the other pilot room, a diaphragm 24
The outlet side pressure is introduced as a force to assist the spring 22.

The traveling priority valves 18, 18 have two outlet ports, and the first outlet port is the traveling side pipes 18, 18
And the other outlet port is connected to the bypass pipelines 25, 25 with check valves, respectively,
5 is connected to the working side conduits 19, 19.

Next, the operation will be described.

(A) When only the work control valve 16 is operated In this case, the pilot pressure is not introduced into the priority switching valve 17, so that the switching valve 17 is in the working position a and the pump discharge oil is preferentially switched. It is supplied only to the working actuator 12 via the valve 17, the working side conduit 19, and the working control valve 16.

In this case, the pump discharge oil is directly supplied to the work control valve 16, so that the pressure loss is small.

(B) When the work control valve 16 is not operated and only one or both of the travel control valves 15L and 15R are operated In this case, the priority switching valve 17 receives the pilot pressure from the travel operation detection circuit 20. To the traveling position b.

In this state, all the pump discharge oil is supplied to the traveling motors 11L and 11R through the traveling priority valve 21 and the operated traveling control valves 15L and 15R, and the traveling operation is performed.

(C) When the travel control valves 15L and 15R and the work control valve 16 are simultaneously operated In this case, the priority switching valve 17 is set to the travel position b by the pilot pressure from the travel operation detection circuit 20. , The pump discharge oil passes through the switching valve 17, and the travel priority valve 2
Enter 1.

At this time, the travel priority valve 21 performs an automatic flow rate setting action of keeping the discharge flow rate from both outlet ports at a set value based on the pressure difference between the inlet side and the outlet side of the throttle 24, as is well known. By the operation of the travel priority valve 21, pump discharge oil is supplied to the travel motors 11L and 11R and the work actuator 12 in a distribution according to the operation amounts of the travel control valves 15L and 15R and the work control valve 16.

This point will be described in further detail. FIG. 2 shows the relationship between the operation amount α (= control valve pilot pressure) of the travel control valves 15L and 15R and the amount Q of oil flowing into the travel motors 11L and 11R. There is.

In the figure, the straight line X represents the α-Q characteristic when the pilot pressure P1 of the work control valve 16 is 0 (when the work control valve 16 is not operated), and the straight line Y represents the maximum pilot pressure P1. The α-Q characteristics are shown respectively, and at the time of simultaneous operation, the automatic flow rate setting action of the travel priority valve 21 causes the travel control valves 15L, 15R to fall within the shaded area between the straight lines X and Y.
Is supplied to the traveling motors 11L and 11R, and the remaining pump discharge oil is supplied to the working device actuator 12.

Thus, at the time of simultaneous operation, the set flow rate of oil is supplied to the traveling motors 11L and 11R regardless of fluctuations in the load pressure of the working device actuator 12.

Therefore, there is no fear that the traveling speed will fluctuate or the straightness will be impaired due to the influence of the load pressure of the working device actuator 12 even when the operations are performed simultaneously.

Since the left and right traveling motors 11L and 11R are driven by separate pumps 13 and 14, as in the case where the left and right traveling motors are connected to one pump in parallel (Japanese Patent Laid-Open No. 1-126407). Also, there is no fear that straightness will be lost due to the difference between the motor load pressures.

Further, since the operation amounts and the speeds of the travel control valves 15L and 15R and the work control valve 16 are accurately proportional to each other, it is possible to easily perform a synchronizing operation for providing a certain correspondence between the travel speed and the work speed. You can

Second Embodiment (see FIG. 3) Only differences from the first embodiment will be described.

In the first embodiment, the α-Q characteristic in the region between the straight lines X and Y in FIG. 2 is determined by the pilot pressure P1 of the work control valve 16.
In the second embodiment, the secondary pressure of the pilot valve 27 whose primary pressure is the hydraulic pressure of the pilot pump 26 is taken into the pilot chamber of the travel priority valve 21, and the secondary pressure P2 The configuration is such that the -Q characteristic can be set.

In this way, the α-Q characteristic during simultaneous operation can be arbitrarily selected and changed by operating the pilot valve 27. Therefore, the traveling speed at the time of simultaneous operation can be freely set and changed.

By the way, in the above embodiment, the traveling control valve 15
Although hydraulic pilot type switching valves are used for the L and 15R and the work control valve 16, respectively, manual switching valves may be used for these.

The present invention is not limited to hydraulic excavators, but can be widely applied to crawler type working vehicles, crawler cranes and other crawler type vehicles.

[0053]

As described above, according to the present invention, the discharge conduit of the pump is provided with the priority switching valve for guiding the pump discharge oil to the travel control valve side when the traveling operation is performed. A travel priority valve with pressure compensation is provided in the pipeline connecting the and travel control valves, and the automatic flow rate setting action of this travel priority valve allows simultaneous operation of the travel control valve and the work control valve.
Since the set amount of oil is supplied to the travel control valve and the remaining amount is supplied to the work control valve, the amount of operation of the travel control valve can be adjusted regardless of fluctuations in the load pressure of the working device actuator. A proportional amount of oil can be supplied to the traction motor.

Further, the left and right traveling motors are driven by separate pumps, and their load pressures do not affect each other.

Therefore, it is possible to prevent the traveling speed from fluctuating and ensure straightness.

Further, during the simultaneous operation, the flow rates on the traveling control valve side and the work control valve side do not change due to mutual load pressure,
Since it corresponds to each operation amount, the operation of synchronizing the traveling speed and the working speed can be easily performed.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an operation amount of a travel control valve and an amount of oil flowing into a travel motor in the embodiment.

FIG. 3 is a hydraulic circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a conventional hydraulic circuit diagram.

[Explanation of symbols]

 11L Left traveling motor C1 First actuator group including left traveling motor 11R Right traveling motor C2 Second actuator group including right traveling motor 13,14 Pump 15L, 15R Travel control valve 16 Work control valve 17 Priority switching valve 20 Travel operation detection Circuit (travel operation detection means) 21 Travel priority valve with pressure compensation 23 Work operation detection circuit (work operation detection means) 27 Pilot valve replacing work operation detection means

Claims (2)

[Claims] 1. A left and right traveling motor that drives the left and right crawlers, and a plurality of work device actuators other than the traveling motor, the first traveling motor including a left traveling motor.
In a crawler type vehicle which is divided into an actuator group and a second actuator group including a right traveling motor, and the first and second actuator groups are driven by different pumps, A travel control valve for controlling the travel motor, a work control valve for controlling the working device actuators of both actuator groups, a travel operation detection unit for detecting that the travel control valve has been operated, and the work device actuator are provided. The operation control means for detecting the operation, the priority switching valve provided in the discharge line of the pump, and the traveling operation detection means and the work operation detection means provided in the outlet side line of the priority switching valve. And a travel priority valve with pressure compensation that operates based on the signal of 1., the priority switching valve having a working position and a travel position. ,
Based on the traveling operation detection signal from the traveling operation detecting means, the working position is switched to the traveling position, and the pump discharge oil at the traveling position is led to the traveling priority valve. At the working position, the pump discharge oil is entirely delivered at the work position. It is configured to lead to a control valve, the travel priority valve, based on a travel operation detection signal from the travel operation detection means and a work operation detection signal from the work operation detection means, to the travel control valve, A hydraulic circuit for a crawler type vehicle, which is configured to supply a set amount of pump discharge oil and supply the remaining amount to a work control valve. 2. The hydraulic circuit for a crawler type vehicle according to claim 1, further comprising a variable secondary pressure pilot valve in place of the work operation detection means, wherein the travel priority valve is the secondary pressure of the pilot valve. Based on a traveling operation detection signal from the traveling operation detection means, a pump discharge oil of a set flow rate is supplied to the traveling control valve, and the remaining amount is supplied to the work control valve. Hydraulic circuit of crawler type vehicle.