JPS607424Y2 - Fluid pressure circuit of backhoe work vehicle with dozer - Google Patents

Description

[Detailed Description of the Invention] The present invention connects the first and second travel operation valves for the left and right travel devices to the first and second pumps respectively, and connects the dozer operation valve to the first travel operation valve. The present invention relates to a fluid pressure circuit for a backhoe operator with a dozer, in which the arm operating valve is integrally constructed as a multiple valve type with a center bypass, and the dozer and arm operating valve are connected to the first pump together with the first travel operating valve.

In the above-mentioned fluid pressure circuit, in order to perform dozer work without causing the vehicle body to skew, and to run and escape from the wetland by increasing the speed of the arm and raking it,
Conventionally, the first travel operation valve was made into a series section type, and the dozer operation valve was connected to the downstream side thereof.
The flow path of the second pump is provided with a valve that allows fluid to flow from the second pump into the arm operating valve, and the merging valve and the arm operating valve are linked, but not only is the merging valve itself expensive, but the merging valve itself is expensive. However, the linkage structure is structurally complicated, and when the dozer cylinder reaches the stroke end, the fluid in the first pump is temporarily relieved, causing the vehicle body to turn.

The present invention aims to eliminate the above-mentioned drawbacks all at once through extremely simple improvements.

Next, embodiments of the present invention will be described in detail based on the drawings.

A swivel base 3 is attached to a vehicle body 2 equipped with left and right crawler traveling devices 1, a backhoe working device 4 is provided on this swivel base 3, a control section 5 and a driving section 6 are mounted on the swivel base 3, and the above-mentioned traveling vehicle body A dozer working device 7 is attached to 2 to form a working vehicle for carrying out excavation and earth removal work.

The backhoe working device 4 includes the swivel base 3
A bracket 10 is attached to an upright base 8 by a fluid pressure cylinder 9 so as to be able to swing freely around a vertical axis, and a boom 11 is pivotally connected to this bracket 10 via a horizontal axis. The arm 12 is pivotally connected to the tip of the arm 12, and the packet 13 is pivotally connected to the tip of the arm 12 via horizontal shafts parallel to the boom swing axis. Cylinders 14, 15, 16 are provided.

The dozer working device 7 has a dozer 17 at its tip.
A pair of left and right arms 18 equipped with
A fluid pressure cylinder 19 is interposed between the two.

As shown in FIG. 2, the fluid pressure circuit of the working vehicle includes a first pump P1, an operating valve V1 for the dozer cylinder 19, and a first motor M1 for one of the left and right traveling devices.
first traveling operation valve V2, arm cylinder 15 for
Operation valve V3 for boom, operation valve V2 for boom extension
, and the operation valve V for the packet cylinder 16, the first traveling operation valve V2 is a series section type, and the first travel operation valve V2 is connected in a multiple valve type with a center bypass in that order,
The second pump P2 has an operation valve ■6 for the boom cylinder 14 and an operation valve ■6 for the swivel base drive motor M.
7, and the second traveling operation valve v8 for the second motor pigeon for the left and right traveling devices are connected in that order in a multiple valve type with center bypass, and both pumps P1. P2 separately drives the motor M□9M2 to operate it in a low speed running state, and both pumps P1. A valve V9 is provided for merging the fluids of P2 and switching to a high-speed running state in which the combined fluid drives the motor M□ and the tag in series, and a valve v1o for switching and connecting the flow path for the swing motor M to the bracket cylinder 9. , the motor flow paths a and a are branched on the downstream side of the second traveling operation valve ■8, and the branched flow paths are connected via check valves 20 and 20, and the flow paths with check valves are was connected to the operation ports of the dozer operation valve ■□ and arm operation valve V3 via merging blocks B□, B2, and the first pump flow path C was branched on the upper side of the dozer operation valve V1. The flow path d is connected to the dozer and travel operation valve V1. v
2 operation port, and the flow path e from the center bypass of the valve group for the second pump P2 is connected to the boom speed increase and packet valve V4. In addition to connecting the operation boat of V6 to each of the arm merging blocks B2, the block salt is provided with a flow path f for connecting the center bypass flow path and the operation boat. The block a to which the branch connection flow path d of pump P□ is connected and the block bird for arm merging are connected to the other valve V2. ■2. A check valve 21.21 is provided to prevent fluid supply to V5.

According to the above configuration, the first and second traveling operation valves V2
．． By operating V8 and the dozer operation valve V□, the fluids of each pump P□ and P2 are divided, and the combined fluid of the divided fluids drives the dozer cylinder 19, and the remaining divided fluid is used to drive both motors ML, M2 can be driven, and even if the dozer cylinder 19 reaches the stroke end in this state, both motors M□9M2 can be kept in the driving state.In other words, the dozer operation can be performed without causing the vehicle body 2 to skew. I can do it.

And travel operation valve v2. By operating V8 and the arm operation valve v3, both motors M1 are driven while driving the arm 12 with a fluid that is a mixture of the return fluid of one valve V2 and the diverted fluid from the lower side of the other valve V8.
9 M2 can be put in a driving state, that is, it is possible to travel and escape from a wetland by operating the arm 12 while traveling.

Note that it is also good to replace the block B1 with a piping structure.

FIG. 3 shows a partial diagram of a modified fluid merging circuit, in which the first running operation valve V2 is of a parallel section type, and the branch flow path d of the first pump P□ is connected to the merging block B2. Thus, the dozer cylinder 19 or the arm cylinder 15 can be driven while both motors M□e M2 are driven at a constant speed by the divided fluid.

In this case, arm operation valve v3 and dozer operation valve V
Even if 1 is connected in reverse, the same working state as described above can be achieved.

As shown in the above embodiments, the feature of the present invention is that the first pump includes an operating valve for the dozer cylinder;
A first traveling control valve for the first motor of the left and right traveling device, an operating valve for the arm cylinder, and an operating valve for the packet cylinder are connected in a multiple valve type with center bypass, and a second pump is connected to the operating valve for the boom cylinder. In a fluid pressure circuit of a backhoe work vehicle with a dozer, in which a second traveling operation valve for a second motor of the left and right traveling devices is connected in a multiple valve type with a center bypass, one of the dozer or arm operation valve is connected A merging flow path with a check valve is located at the most upstream side of the center bypass and branched from the motor flow path on the downstream side of the second traveling operation valve;
A branch connection flow path that is connected to the operation boat of the dozer operation valve and the arm operation valve via a merging block, and has a first pump flow path branched on the upper side of the dozer operation valve or the arm operation valve, a block connected to the dozer operation valve or the arm operation valve and the operation port of the first travel operation valve, and connected to the branch connection flow path of the first pump to the dozer operation valve;
Each of the merging blocks to the arm operation valve is provided with a check valve that prevents fluid from being supplied from the merging channel to the other valve connected to the first pump, and from this configuration, the following can be achieved. It has the following effects.

That is, instead of using expensive merging valves and linking structures therefor, the improvement is made by simply incorporating into the fluid pressure circuit a merging block and a merging channel that have a simple structure and do not require linking operations.
As shown in the example, the dozer work is performed without causing skew, or the work of escaping from a wetland is performed by increasing the speed of the arm while traveling, and in addition, during the dozer work, the dozer cylinder stroke Even when the end is reached, the vehicle body does not turn, and as a whole, the fluid pressure circuit can be simplified in an extremely economical manner.

[Brief explanation of drawings]

The drawings show an embodiment of the fluid pressure circuit of a backhoe work vehicle with a dozer according to the present invention, and FIG. 1 is an overall side view of the work vehicle;
FIG. 2 is a fluid pressure circuit diagram, and FIG. 3 is a partial circuit diagram of fluid merging in a modified example. 14...Boom cylinder, 15...Arm cylinder, 16...Packet cylinder, 1
9... Dozer cylinder, 21... Check valve, a... Motor flow path, b... Merging flow path, C...・First pump flow path, d...
Branch connection flow path, B=-B2... Merging block, M□... First motor, M2... Second
Motor, P□... 1st pump, P2...
・Second pump, Vl...Dozer operation valve, V
2...First travel operation valve, v3...
Arm operation valve, V5...Packet operation valve, V6...Boom operation valve, ■8...
...Second traveling operation valve.

Claims (1)

[Claims for Utility Model Registration] The first pump P□ includes an operating valve V1 for the dozer cylinder 19, a first traveling operating valve V2 for the first motor M1 of the left and right traveling devices, an operating valve V3 for the arm cylinder 15, and a packet. The operating valve V5 for the cylinder 16 is connected in a multiple valve type with center bypass, and the operating valve V6 for the boom cylinder 14 is connected to the second pump P2, and the second motor M for the left and right traveling devices is connected to the second pump P2.
A fluid pressure circuit for a backhoe operator equipped with a dozer, in which a second travel operation valve V3 for the second traveling operation valve V3 is connected to the center bypass valve in a multiple valve type with a center bypass, and one of the dozer or arm operation valves V□, v3 is connected to the center bypass valve. The dozer operation valve V0 and the arm operation valve are located at the most upstream side of the bypass and are connected to the motor flow path a on the downstream side of the second travel operation valve V3, and a merging flow path with a check valve branched from a. For the operation port of V3, merge block B1. A branch connection flow path d, which is connected via Bll and branched off from the first pump flow path C on the upper side of the dozer operation valve V1 or the arm operation valve v3, is connected to the dozer operation valve ■1 or the arm operation valve V3 and the first pump flow path C. A block B□ connected to the operation port of the first travel operation valve V2 and connected to the branch connection passage d of the first pump P□ to the dozer operation valve V□, and a block for merging to the arm operation valve V3. B2, and another valve V connected to the first pump P1 from the merging channel to the first pump P1.
2. V. (2) A fluid pressure circuit for a backhoe operator equipped with a dozer, characterized in that it is provided with a check valve 21.21 for blocking fluid supply to the dozer.