JPH1136379A - Hydraulic system of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic system of a working vehicle which can travel at a high speed by adding the hydraulic oil supplied from a sub-hydraulic pump to the right and left traveling motors when the right and left traveling motors are driven for traveling. SOLUTION: The hydraulic oil supplied from main hydraulic pumps P1, P2 is sent to right and left traveling motors 3R, 3L and the first working actuators (a boom cylinder 4, a bucket cylinder 5, an arm cylinder 6, a service actuator 10, etc.) And the hydraulic oil supplied from a sub-hydraulic pump P3 is sent to the second working actuators (a slewing motor 7, a swing cylinder 8, a dozer cylinder 9, etc.). And a changeover means is actuated when the right and left traveling motors 3R, 3L are being driven, and the hydraulic oil supplied from the sub-hydraulic pump P3 can be supplied to the right and left traveling motors 3R, 3L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydraulic system for a working vehicle such as a backhoe.

[0002]

2. Description of the Related Art A working vehicle such as a backhoe drives a plurality of hydraulic pumps P1, P2, and P3 with an engine, and the hydraulic oil of the hydraulic pumps P1, P2 is supplied to left and right traveling motors 3L, 3L.
R, boom cylinder 4, bucket cylinder 5, arm cylinder 6, swing motor 7, swing cylinder 8, dozer cylinder 9, and external detachable service actuator (attachment) 10 such as a breaker via a service port. (See FIG. 1 showing an embodiment of the present invention).

The main hydraulic pumps P1 and P2 use variable displacement pumps, and the hydraulic pumps support each other, so that the bias of the hydraulic pressure and the oil amount can be eliminated to always maintain an appropriate hydraulic pressure. The pressure oil from the first main hydraulic pump P1 is supplied to the right traveling motor 3R, the boom cylinder 4 and the bucket cylinder 5, and the pressure oil from the second main hydraulic pump P2 is supplied to the left traveling motor 3L, the arm cylinder 6 and the service actuator 10. Respectively, and supplies the hydraulic oil from the third sub-hydraulic pump P3 to the swing motor 7, the swing cylinder 8, and the dozer cylinder 9, so that even if a front operation (an operation of a boom, a bucket, an arm, etc.) is performed during traveling, it is bent. In order to allow the vehicle to travel straight without traveling, a switching diversion valve 11 is provided to supply hydraulic oil from the sub hydraulic pump P3 to the boom cylinder 4 and the bucket. Linda 5, and supplies it to the arm cylinder 6 and the service actuator 10.

[0004]

In the above prior art, the hydraulic oil from the sub hydraulic pump P3 is supplied to the swing motor 7, the swing cylinder 8, the dozer cylinder 9, the boom cylinder 4,
Although it can be supplied to work actuators such as the bucket cylinder 5, the arm cylinder 6, and the service actuator 10, it is not supplied to the left and right traveling motors 3L and 3R. The amount is only for the two main hydraulic pumps P1 and P2, and it is difficult to increase the traveling speed.

[0005] The present invention provides a hydraulic system for a working vehicle which is capable of running at high speed by supplying hydraulic oil from a sub-hydraulic pump to the left and right traveling motors 3L and 3R when the left and right traveling motors are driven to travel. The purpose is to provide.

[0006]

The first concrete means for solving the problem in the present invention is a main hydraulic pump P1,
The pressure oil from P2 is supplied to the left and right traveling motors 3L, 3R and the first type working actuators (boom cylinder 4, bucket cylinder 5, arm cylinder 6, service actuator 10, etc.), and the pressure oil from the sub hydraulic pump P3 is supplied. It is supplied to the second type working actuators (swing motor 7, swing cylinder 8, dozer cylinder 9, etc.), and the switching means is operated when the left and right traveling motors 3L, 3R are driven, so that the sub-hydraulic pump P3 supplies That is, pressure oil can be supplied to the left and right traveling motors 3L and 3R.

Thus, the left and right traveling motors 3L, 3R
Is supplied not only with the hydraulic oil of the main hydraulic pumps P1 and P2, but also with the hydraulic oil from the sub hydraulic pump P3. A second specific means for solving the problem in the present invention is to supply the hydraulic oil from the main hydraulic pumps P1, P2 to the left and right traveling motors 3L, 3R and the first type working actuator, and to supply the hydraulic oil from the sub hydraulic pump P3. The pressure oil is supplied to the second type working actuator, and the switching means is operated when the left and right traveling motors 3L, 3R are driven to supply the pressure oil from the sub hydraulic pump P3 to the left and right traveling motors 3L, 3R. That is, the actuator can be supplied to the first type working actuator.

Accordingly, the left and right traveling motors 3L, 3R
Not only the hydraulic oil of the main hydraulic pumps P1 and P2 but also the hydraulic oil from the sub-hydraulic pump P3 is supplied, and an increase in the amount of oil enables high-speed traveling, and the operation of the first-class working actuator by the sub-hydraulic pump P3. Is also secured. A third specific means for solving the problem in the present invention is to supply pressure oil from the main hydraulic pumps P1 and P2 to the left and right traveling motors 3L and 3R and the first type working actuator,
The pressure oil from the sub-hydraulic pump P3 is supplied to the second-type working actuator, and the switching means is operated when the left and right traveling motors 3L and 3R are driven to divide the pressure oil from the sub-hydraulic pump P3. 3L left and right traveling motor,
That is, 3R can be supplied and another stream can be supplied to the second type working actuator.

Thus, the left and right traveling motors 3L, 3R
Not only the hydraulic oil of the main hydraulic pumps P1 and P2 but also the hydraulic oil from the sub-hydraulic pump P3 is supplied, so that high-speed traveling is possible by increasing the amount of oil, and furthermore, the operation of the second-class working actuator by the sub-hydraulic pump P3. Is also secured. A fourth specific means for solving the problem in the present invention is that, in addition to the second or third specific means, the left and right traveling motors 3L, 3D,
3R is supplied preferentially, and the surplus flow is supplied to the working actuator.

[0010] With this arrangement, the hydraulic oil of the sub-hydraulic pump P3 is preferentially supplied to the left and right traveling motors 3L, 3R while the operation of the working actuator is secured during straight traveling, thereby enabling high-speed traveling.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the first embodiment of the backhoe hydraulic system schematically shown in FIG. 1 and divided into left and right parts in FIGS. 2 and 3, respectively, four hydraulic pumps P1, P2, P3 and P4 are driven by the engine 13 to The hydraulic oil of the main hydraulic pumps P1, P2 of the continuous variable displacement type is supplied to the control valves C1, C2
The traveling motor 3 of the crawler type left and right traveling device via 2
L, 3R, and control valves C3, C4, C5,
Boom cylinder 4, bucket cylinder 5,
The power is supplied to the first working actuator such as the arm cylinder 6 and the service actuator (attachment) 10.

The service actuator 10 is a breaker, an auger, a cutter, or the like, and has various hydraulic capacities. The service actuator 10 is detachably connected to the service port 14 of the backhoe. The main hydraulic pump P1, the control valve C1,
A first hydraulic circuit is formed by the traveling motor 3R, the control valves C3 and C4, the boom cylinder 4, the bucket cylinder 5, and the like. The main hydraulic pump P2, the control valve C2, the traveling motor 3L, the control valves C5 and C6, the arm The second hydraulic circuit is formed by the cylinder 6, the service actuator 10, and the like, and the boom cylinder 4, the bucket cylinder 5, the arm cylinder 6, the service actuator 10, and the like are the first type work actuator.

The hydraulic oil from the third sub-hydraulic pump P3 is supplied to the swing motor 7, the control motor C7, C8 and C9 via the control valves C7, C8 and C9.
It can be supplied to the second-type working actuators such as the swing cylinder 8 and the dozer cylinder 9 and can also be supplied to the switching diversion valve 11, and these form a third hydraulic circuit. The switching diversion valve 11 is of a two-position switching type between a distribution position and a diversion supply position, and when operated to the diversion supply position, communicates with the two oil passages 24 and 25 to equally divide the pressure oil of the sub hydraulic pump P3. Supply to the oil passages 24 and 25 becomes possible.

The divided stream of pressure oil of the sub hydraulic pump P3 can be supplied to the boom cylinder 4 and the bucket cylinder 5 through the oil passage 24 and the control valves C3 and C4, and the main hydraulic pump P1 Is supplied to the suction side of the control valve C1 to which the pressurized oil is supplied, so that the traveling motor 3R can be driven. The divided other flow passes through the oil passage 25 via the control valves C5 and C6, and the arm cylinder 6, In addition to being able to supply the service actuator 10, the pressure oil of the main hydraulic pump P2 is supplied to the suction side of the control valve C2 to be supplied, and the traveling motor 3L can be driven.

The control valves C3, C4, C5, C7 and the switching diverting valve 11 are of a hydraulic pilot switching type.
Hydraulic oil from the pilot pressure hydraulic pump P4 passes through the swash plate angle changing travel speed switching valve 17, the unload valve 18, and the control valves C3, C4,
The oil is supplied to C5 and C7, and is supplied to the switching flow dividing valve 11 via the oil passage 20.

A pilot pressure control oil passage 21 is connected to the oil passage 20 of the switching flow dividing valve 11. The pilot pressure control oil passage 21 is provided between the oil passage 20 and the left and right traveling motors 3L,
It has a first control oil passage 21A that drains oil through the 3R control valves C1 and C2, and a second control oil passage 21B that drains oil from the oil passage 20 through the control valves C1 to C6. Next, the operation of the hydraulic system will be described.

When the left and right traveling motors 3L and 3R are not driven without operating the control valves C1 and C2, the main hydraulic pump P
1 can be supplied to the boom cylinder 4 and the bucket cylinder 5, the oil of the main hydraulic pump P2 can be supplied to the arm cylinder 6 and the service actuator 10, and the oil of the sub hydraulic pump P3 can be supplied to the swing motor 7, the swing cylinder 8 and the dozer cylinder 9.

When the control valves C1 and C2 are operated for straight traveling, the oil of the main hydraulic pumps P1 and P2 is supplied to the left and right traveling motors 3L and 3R to drive them.
1, pilot pressure control oil passage 21 by switching C2
Is blocked, the pilot pressure rises, the switching diversion valve 11 is operated to change the distribution position from the distribution position to the diversion supply position, and the oil of the sub hydraulic pump P3 is supplied to the right traveling motor 3R, the left traveling motor 3L, the boom cylinder 4, and the bucket. It can be supplied to the cylinder 5, the arm cylinder 6, and the service actuator 10.

Therefore, at this time, the second type working actuators of the swing motor 7, the swing cylinder 8 and the dozer cylinder 9 are in an operable state, and the boom cylinder 4, the bucket cylinder 5, the arm cylinder 6 and the first The seed actuators are also in an operable state, and if they are not operated, all the oil of the sub hydraulic pump P3 is supplied to the left and right traveling motors 3L, 3R, and the speed is increased more than when only the main hydraulic pumps P1, P2 are used. You.

The switching diversion valve 11, the oil passages 24 and 25 from the switching diversion valve 11 to each control valve C, the oil passage 20, and the pilot pressure control oil passage 21
When the L and 3R are switched to drive, the switching flow dividing valve 11 is operated to supply the hydraulic oil from the sub hydraulic pump P3 to the left and right traveling motors 3L and 3R, the boom cylinder 4, the bucket cylinder 5, the arm cylinder 6, and the service cylinder. A switching unit for supplying the actuator 10 is configured.

The switching means includes a switching flow dividing valve 11.
Boil cylinder 4, bucket cylinder 5, arm cylinder 6 and service actuator 10
The left and right traveling motors 3L, 3L
R, or by providing a switching diversion valve 11 between the sub-hydraulic pump P3 and the control valve 8 so that the oil of the sub-hydraulic pump P3 is not supplied to the second-type working actuator during straight running. Alternatively, only the left and right traveling motors 3L and 3R may be supplied.

In the second embodiment shown in FIG. 4, the oil diverted at the diversion supply position of the switching diversion valve 11 is further reduced by two priority diversion valves (flow priority valves) 26 and 27 provided in respective circuits. Dividing into books. The oil passage 24 is connected to the suction side of the control valve C1 to which the pressure oil of the main hydraulic pump P1 is supplied and drives the traveling motor 3R, and the priority oil passage 24A is connected to the control valves C3 and C4 and the boom cylinder 4 And a surplus oil passage 24B for operating the bucket cylinder 5.

The oil passage 25 is connected to the suction side of the control valve C2 to which the pressure oil of the main hydraulic pump P2 is supplied, and drives the traveling motor 3L to drive the traveling motor 3L; and the control valves C5 and C6.
Connected to the arm cylinder 6 and a surplus oil passage 25B for operating the service actuator 10. When the control valves C1 and C2 are operated for straight traveling, the oil of the main hydraulic pumps P1 and P2 is supplied to and drives the left and right traveling motors 3L and 3R, and the switching valve 11 is switched by switching the control valves C1 and C2. Is operated to change to the branch flow supply position, and the oil of the sub hydraulic pump P3 is preferentially supplied to the right traveling motor 3
R and the left traveling motor 3L are supplied, and surplus oil is supplied to first-class working actuators such as the boom cylinder 4, the bucket cylinder 5, the arm cylinder 6, and the service actuator 10.

In the third embodiment shown in FIG. 5, the pressure oil of the sub-hydraulic pump P3 is supplied to the control valve C9 of the dozer cylinder 9, the switching flow dividing valve 11, and the control valve C of the swing motor 7.
7. The control valve C8 of the swing cylinder 8 and the control valve C6 of the service actuator 10 are supplied so as to pass in the above order. When the switching diversion valve 11 is off, the switching diversion valve 11 is in a communicating state to allow the pressure oil of the sub-hydraulic pump P3 to pass therethrough. When the switching diversion valve 11 is on, the constant flow is divided preferentially. 3R control valves C1, C
2 and the excess flow is supplied to the control valves C6 to C8.

The third embodiment focuses on the fact that a straight traveling is required when the backhoe travels on the road and when performing the dozer work.
3 can be preferentially supplied to the left and right traveling motors 3L, 3R. Note that the present invention is not limited to the above embodiment, and can be variously modified.
For example, the work vehicle may be a wheel loader other than the backhoe, and the switching flow dividing valve 11 may be configured by an electromagnetic valve.

[0026]

According to the present invention described in detail above, the switching means is operated when the left and right traveling motors 3L, 3R are driven, and the hydraulic oil from the sub hydraulic pump P3 is supplied to the left and right traveling motors 3L, 3R. , The left and right traveling motors 3L, 3R can travel at high speed by increasing the oil amount.

When the hydraulic oil from the sub hydraulic pump P3 is supplied to the left and right traveling motors 3L and 3R, the operation of the type 1 work actuator or the type 2 work actuator is ensured, It is possible to preferentially supply the left and right traveling motors 3L, 3R while ensuring the operation of the actuator.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a first embodiment of a hydraulic system for a work vehicle according to the present invention.

FIG. 2 is a detailed explanatory diagram showing a right half of the hydraulic system.

FIG. 3 is a detailed explanatory diagram showing a left half of the hydraulic system.

FIG. 4 is a detailed explanatory view showing a main part of a second embodiment of the present invention.

FIG. 5 is a schematic explanatory view showing a third embodiment of the present invention.

[Explanation of symbols]

 3 Traveling Motor 4 Boom Cylinder 5 Bucket Cylinder 6 Arm Cylinder 7 Swing Motor 8 Swing Cylinder 9 Dozer Cylinder 10 Service Actuator 11 Switching Dividing Valve 24 Circuit 25 Circuit P1 Main Hydraulic Pump P2 Main Hydraulic Pump P3 Sub Hydraulic Pump C Control Valve

Claims (4)

[Claims] 1. A hydraulic oil from a main hydraulic pump is supplied to a left and right traveling motor and a first type working actuator, and a hydraulic oil from a sub hydraulic pump is supplied to a second type working actuator, and the left and right traveling motor is driven. A hydraulic system for a work vehicle, characterized in that the switching means is operated when the operation is being performed, so that pressure oil from the sub-hydraulic pump can be supplied to the left and right traveling motors. 2. The pressure oil from the main hydraulic pump is supplied to the left and right traveling motor and the first type working actuator, and the pressure oil from the sub hydraulic pump is supplied to the second type working actuator, and the left and right traveling motor is driven. The hydraulic system for a work vehicle, characterized in that the switching means is operated when the operation is being performed, so that the pressure oil from the sub-hydraulic pump can be supplied to the left and right traveling motors and can be supplied to the first type work actuator. . 3. The hydraulic oil from the main hydraulic pump is supplied to the left and right traveling motor and the first type working actuator, and the pressure oil from the sub hydraulic pump is supplied to the second type working actuator, and the left and right traveling motor is driven. Operating the switching means while the operation is being performed to divide the pressure oil from the sub-hydraulic pump so that one stream can be supplied to the left and right traveling motors and the other stream can be supplied to the second type actuator. Characteristic hydraulic system for work vehicles. 4. The method according to claim 2, wherein the pressure oil from the sub-hydraulic pump is preferentially supplied to the left and right traveling motors via the priority diverting valve, and the excess flow is supplied to the working actuator. The working vehicle hydraulic system as described.