JP2000328607A - Hydraulic circuit of self-travelling work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the hydraulic circuit of a work machine by utilizing the PTO hydraulic pump of a self-travelling work machine provided with a travelling hydraulic pump, a travelling hydraulic motor and the PTO hydraulic pump as a pilot hydraulic oil source. SOLUTION: The suction port 23 of a hydraulic direction changeover valve 22 is communicated with and connected to the discharge port of a PTO hydraulic pump 21. Next, the discharge port of one hand of the changeover valve 22 is connected to a breaker 26 through a PTO hydraulic taking-out coupler 25. Next, the discharge port 27 of the other hand is connected to the transmission receiving part 29 of a travelling hydraulic motor 28, and the hydraulic pump 21 is utilized as a pilot hydraulic source. Furthermore, when a pedal 32 is neutral, the receiving part 29 is communicated with a tank 23, and the motor 28 is changed to first speed. When the left side of the pedal 32 is stepped, the motor 28 is changed to the first speed, when the right side is stepped, the pump 28 is changed to second speed, and a breaker 26 stops. Thereby a production cost can be reduced without requiring any pilot hydraulic pump and solenoid hydraulic valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydraulic circuit for a self-propelled working machine.

[0002]

2. Description of the Related Art Conventionally, a traveling hydraulic pump and a PTO hydraulic pump are provided, and a traveling hydraulic motor that can be shifted in two stages by pilot hydraulic pressure is driven by the traveling hydraulic pump, and a breaker or the like is driven by the PTO hydraulic pump. There is a self-propelled working machine that drives an optional working machine.

[0003] A pilot hydraulic pump is separately provided for the shifting operation of the traveling hydraulic motor, and the pilot hydraulic pump is connected to a shifting operation receiving portion of the traveling hydraulic motor via an electromagnetic hydraulic valve. Controlling the pressure oil supplied to the shift operation receiving portion by the switching operation of the electromagnetic hydraulic valve,
The gear shifting operation is performed.

[0004]

However, the above-described self-propelled working machine has a problem that the structure is complicated and a manufacturing cost is increased because a pilot hydraulic pump and an electromagnetic hydraulic valve are required.

[0005] Further, there is another problem that a pedal for turning on / off the optional work implement and a pedal for shifting operation are required, and the driver's feet become cramped, which hinders the driving operation.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a self-propelled working machine including a traveling hydraulic pump, a traveling hydraulic motor that can be shifted in two stages by pilot hydraulic pressure, and a PTO hydraulic pump. And a hydraulic circuit for a self-propelled working machine, wherein the hydraulic pump for PTO can be used as a pilot hydraulic pressure source.

[0007] The present invention also has the following features.

[0008] A hydraulic directional control valve is communicatively connected to the discharge port of the PTO hydraulic pump, one discharge port of the hydraulic directional control valve is communicatively connected to the PTO hydraulic take-out coupler, and the other discharge port is connected to the travel hydraulic motor. Communicated and connected to the speed change operation receiving part.

[0009] A seesaw type pedal is provided in the operating unit, and the pedal is interlocked with the hydraulic direction switching valve. When the pedal is depressed, the communication destination of the discharge port of the PTO hydraulic pump is changed to a PTO hydraulic take-out coupler. It can be switched to either of the gear change operation receiving part.

A throttle is provided between the hydraulic direction switching valve and the shift operation receiving portion, and a part of the pressure oil discharged from the PTO hydraulic pump is bleed off through the throttle.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention are as follows.

A power shovel as a self-propelled working machine is:
Equipped with a traveling hydraulic pump and a PTO hydraulic pump linked to the engine, and a traveling hydraulic motor that can be shifted in two stages by pilot hydraulic pressure linked to the crawler type traveling unit. The hydraulic motor is driven to connect the pressure oil of the PTO hydraulic pump to the PTO hydraulic take-out coupler.

The PTO hydraulic pump is connected to a hydraulic directional switching valve operatively connected to a seesaw type pedal, and one discharge port of the hydraulic directional switching valve is connected to a PTO hydraulic take-out coupler. Is connected to the shift operation receiving portion of the traveling hydraulic motor so as to enable the shifting operation of the traveling hydraulic motor by operating the pedal, so that the PTO hydraulic pump can also be used as a pilot hydraulic source.

[0014]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a power shovel B as a self-propelled working machine having a hydraulic circuit A according to the present invention.
In the excavator B, an airframe 2 is mounted on the traveling unit 1 so as to be able to turn left and right, and excavation work unit 3 disposed in front of the airframe 2 excavates earth and sand and transfers it to a truck or the like. ing.

The traveling section 1 has a traveling section frame 5 equipped with a pair of right and left crawlers 4, a substantially cylindrical turning base 6 is erected substantially at the center of the traveling section frame 5, and the body frame 7 is mounted on the upper surface of the turning base 6. It is mounted so that it can turn left and right.

The airframe 2 is provided with an operation stand 9 having various operation levers 8 arranged at the front end of the upper surface of the airframe 7, and a traveling hydraulic pump interlocked with the engine from the middle to the rear of the airframe 7. A motor unit 10 including a PTO hydraulic pump 21 and a hydraulic control valve is disposed, and a seat 11 is mounted on an upper surface of the motor unit 10.

The excavating work part 3 has a bracket 12 projecting from the center of the front end edge of the body frame 7, and the working part base 13 is pivotally attached to the bracket 12 so as to swing right and left. The boom 14, the arm 15, and the bucket 16 are sequentially connected in the above order so as to be vertically rotatable.
7. With the arm cylinder 18 and the bucket cylinder 19 interposed, the earth and sand are scooped into the bucket 16 by the expansion and contraction operations of the cylinders 17, 18, 19, and the bucket is
The sediment in 16 is loaded on trucks.

The hydraulic circuit A, as shown in FIG.
The discharge port of the hydraulic pump 21 for TO is connected to the suction port 23 of a hydraulic directional switching valve 22 of a spring center type. Breaker 26 as a machine
And the other discharge port 27 is connected to the traveling hydraulic motor.
The PTO hydraulic pump 21 can be used as a pilot hydraulic power source for a gear shifting operation by being connected to a gear shift operation receiving portion 29 of the PTO.

Further, the spool 30 of the hydraulic directional control valve 22
When the pedal 32 is in the neutral position, the hydraulic oil discharged from the PTO hydraulic pump 21 is directly linked to the hydraulic oil tank 33 when the pedal 32 is in the neutral position. When the shift operation receiving portion 29 is communicated with the hydraulic oil tank 33 to release the pilot oil pressure, the traveling hydraulic motor 28 is shifted to the first speed, and when the left side of the pedal 32 is depressed, the PT
The O hydraulic pump 21 and the PTO hydraulic take-out coupler 25 communicate with each other to operate the breaker 26, release the pilot hydraulic pressure, shift the traveling hydraulic motor 28 to one speed, and
When the right side of the step 32 is depressed, the PTO hydraulic pump 21 and the shift operation receiving portion 29 of the traveling hydraulic motor 28 communicate with each other. At the second speed, and the operation of the breaker 26 is stopped.

A throttle 34 is provided in the hydraulic direction switching valve 22 to bleed off a part of the pressure oil discharged from the PTO hydraulic pump 21. 29 is prevented from being damaged.
In the figure, 35 is a relief valve, 36 is a check valve, and 37 is an in-line filter.

As described above, the PTO hydraulic pump 21 can also be used as a pilot hydraulic source for the shifting operation of the traveling hydraulic motor 28 simply by interposing the hydraulic direction switching valve 22 in the hydraulic circuit A. Unlike the related art, a pilot hydraulic pump, a hydraulic solenoid valve, and the like are not required, so that the structure is simplified and the manufacturing cost can be reduced.

Further, the ON / OFF operation of the breaker 26 and the shifting operation of the traveling hydraulic motor 28 can be operated with a single pedal 32, so that the structure is further simplified, and the space at the foot of the driver is effectively used. can do.

[0024]

According to the present invention, the following effects can be obtained.

According to the first aspect of the present invention, there is provided a self-propelled working machine comprising a traveling hydraulic pump, a traveling hydraulic motor capable of being shifted in two stages by pilot oil pressure, and a PTO hydraulic pump. By making the hydraulic pump available as a pilot hydraulic source, the structure is simplified without the need for a pilot hydraulic pump or electromagnetic hydraulic valve, etc.
Manufacturing costs can be reduced.

According to the second aspect of the present invention, a hydraulic directional switching valve is communicatively connected to the discharge port of the PTO hydraulic pump, and one discharge port of the hydraulic directional switching valve is communicatively connected to the PTO hydraulic take-out coupler, and the other is connected. By connecting the discharge port to the shift operation receiving portion of the traveling hydraulic motor, the PTO hydraulic pump can be used as a pilot hydraulic pressure source.

According to a third aspect of the present invention, a seesaw type pedal is provided in the operating section, and the pedal is connected to the hydraulic direction switching valve in an interlocking manner, and when the pedal is depressed, the discharge port of the PTO hydraulic pump is opened. Since the communication destination can be switched between the PTO hydraulic pressure take-out coupler and the shift operation receiving portion, ON / OFF of the optional work machine and shift operation of the traveling hydraulic motor can be performed with a single pedal. Not only simplifies the structure, but also prevents erroneous operations such as shifting operations while the optional work equipment is in operation, making driving easier, and effectively utilizing the space under the driver's feet can do.

According to the fourth aspect of the present invention, a throttle is provided between the hydraulic direction switching valve and the shift operation receiving portion, and a part of the pressure oil discharged from the PTO hydraulic pump through the throttle is bleed off. By doing so, excessive hydraulic pressure does not act on the shift operation receiving portion, and damage around the shift operation receiving portion can be prevented.

[Brief description of the drawings]

FIG. 1 is a side view of a self-propelled working machine including a hydraulic circuit according to the present invention.

FIG. 2 is a hydraulic circuit diagram.

[Explanation of symbols]

 A hydraulic circuit B power shovel (self-propelled work machine) 20 traveling hydraulic pump 21 PTO hydraulic pump 22 hydraulic directional control valve 24 one discharge port 25 PTO hydraulic take-out coupler 27 the other discharge port 28 traveling hydraulic motor 29 speed change Operation receiving part 31 Operating part 32 Pedal 34 Aperture

Claims (4)

[Claims] 1. A traveling hydraulic pump (20), a traveling hydraulic motor (28) that can be shifted in two stages by pilot hydraulic pressure,
Self-propelled work machine (B) equipped with PTO hydraulic pump (21)
3. The hydraulic circuit for a self-propelled working machine according to claim 1, wherein the PTO hydraulic pump (21) can be used as a pilot hydraulic pressure source. 2. A hydraulic directional control valve (22) is communicatively connected to a discharge port of a PTO hydraulic pump (21), and one discharge port (24) of the hydraulic directional control valve (22) is connected to a PTO hydraulic take-out coupler (22). 25) and the other discharge port (27) is connected to the traveling hydraulic motor.
2. The hydraulic circuit for a self-propelled working machine according to claim 1, wherein the hydraulic circuit is connected to the shift operation receiving portion (29) of (28). 3. An operation section (31) is provided with a seesaw-type pedal (32), and the pedal (32) is operatively connected to the hydraulic directional switching valve (22). And a communication destination of a discharge port of the PTO hydraulic pump (21) can be switched to one of a PTO hydraulic take-out coupler (25) and a shift operation receiving portion (29). The hydraulic circuit of the self-propelled working machine as described. 4. A throttle (34) is provided between the hydraulic direction switching valve (22) and the shift operation receiving portion (29), and the throttle valve (34) is provided through the throttle (34).
The hydraulic circuit for a self-propelled working machine according to any one of claims 1 to 3, wherein a part of the pressure oil discharged from the hydraulic pump for TO (21) is bleed off.