JPH0351409Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention provides two fluid pressure pumps for driving fluid pressure motors attached to each of the left and right traveling devices, and one of the pumps is connected to one of the pumps for driving one of the traveling devices. A fluid pressure motor for the device is connected to the other pump, and a fluid pressure motor for the other traveling device is connected to the other pump, and a fluid pressure pump for driving the earth removal work device is connected, separately from both fluid pressure pumps for the traveling device. This invention relates to a fluid pressure circuit for a backhoe equipped with an earth removal device.

This type of excavator equipped with an earth removal device is used for earthwork work on extremely uneven ground using an earth removal device.
When leveling the ground or transporting vehicles in areas with relatively good road conditions, there is a desire to change the running speed of the vehicle considerably, so conventionally, (a) the fluid pressure circuit for the left and right traveling devices is A shift valve mechanism that switches between a first state in which fluid from both pumps is separately supplied to the left and right travel system and a second state in which combined fluid from both pumps is serially supplied to the left and right travel system. By switching the valve mechanism, the oil discharged from both hydraulic pumps for the traveling device is supplied in series or in parallel to the hydraulic motor of the traveling device, and the speed is changed to two stages. (For example, Japanese Utility Model Application Publication No. 54-72289) (b) A pump for driving the earth removal work device, which is provided separately from the fluid pressure pump for driving the traveling device, is merged with the fluid pressure pump for driving the traveling device. The technology of (a) and (b) above is configured so that it can be freely switched between a state where the merging occurs and a state where the merging is canceled, and the gears are shifted in two stages, high and low. Although it was used, the former (a)
According to the technology, in the first state, the vehicle can travel straight even on uneven ground, and in the second state, it can travel at high speed, but the speed difference between high and low gears is It is determined by the capacity of the hydraulic pump for travel, so if you increase the size of the fluid pressure pump itself and try to make the high speed side sufficiently high for high speed travel, it will be necessary to sufficiently reduce the travel speed on the low speed side for safe travel. However, in the opposite case, it is difficult to obtain sufficient high speed.

In addition, according to the latter technology (b), the discharged oil from the fluid pressure pump for the soil removal work equipment, which does not have a large capacity, is distributed and supplied to the fluid pressure motors for driving both traveling equipment. There was a problem that it was difficult to obtain a sufficient speed difference.

The present invention is designed to improve the hydraulic circuit of the above-mentioned excavator equipped with an earth-ejecting device so that sufficient high-speed and low-speed operation can be achieved while avoiding the increase in cost such as adding a separate hydraulic pump. The purpose is to widen the range of changes in traveling speed compared to a backhoe equipped with a device.

The characteristic configuration of the present invention for achieving the above object is that two fluid pressure pumps are provided for driving the fluid pressure motors attached to each of the left and right traveling devices, and one of the pumps has the following features: The fluid pressure motor for one traveling device is connected to the other pump, and the fluid pressure motor for the other traveling device is connected to the other pump. In the fluid pressure circuit of a bucket hoe with an earth removal device provided with a fluid pressure pump, the fluid pressure circuit for the left and right traveling devices has a first state in which fluid from both the pumps is separately supplied to the left and right traveling device systems; A speed change valve mechanism is provided for switching to a second state in which the combined fluid from both pumps is serially supplied to the left and right travel device system, and a fluid pressure circuit for the earth removal work device is provided with A merging valve mechanism is provided for switching the fluid from the fluid pressure pump to a state where the fluid is merged and supplied to the merging fluid when the earth removal device is not in use, and further, a merging supply flow path from the valve mechanism is connected to the merging fluid. It is connected to the upper side of the flow path than the speed change valve mechanism, and this configuration provides the following functions and effects.

That is, a first state in which the fluid pressure motors of the left and right traveling devices are driven at low speed by supplying fluid from two pumps separately, and a first state in which fluid from both pumps is supplied in series to drive them at high speed. There are three types of drive modes: a second state, and a third state in which the supply fluid from the drive pump to the earth removal work device when not in use is combined to drive the earth removal device at a higher speed.
This was achieved without adding a special drive pump.

In other words, with this type of backhoe equipped with an earth removal device, work is generally performed in the first state, which is the slowest speed, and the second state, which is faster. The reason for this is when transporting equipment that does not require earth removal work or when driving on the road in non-working conditions, and at this time the earth removal equipment is usually not in use.
By effectively utilizing the drive pump for the earth removal equipment when it is not in use, we were able to achieve even higher speed travel without increasing the size or number of travel drive pumps. It was possible to rationally achieve this diversification.

Further, a confluence circuit is provided in the fluid pressure circuit to the earth removal work device for switching the fluid from the fluid pressure pump to the earth removal work device to a state where it is combined and supplied to the combined fluid when the earth removal work device is not in use. By providing a valve mechanism for excavation work with a bathoe, after the earth removal work equipment is placed in a tensioned position, the fluid supply to the earth removal work equipment side is cut off and the excavation work with a bathoe is performed. It is also possible to supply as much fluid as possible to various work devices and perform backhoe work efficiently.

Furthermore, a first state in which fluid from a pump for driving the earth removal work device and fluid from both pumps for left and right traveling devices are separately supplied to a traveling fluid pressure motor, and a combined fluid from both pumps is supplied to both traveling devices. Since it merges on the flow path upstream side of the speed change valve mechanism that switches to the second state where fluid pressure is supplied in series to the fluid pressure motor, for example, the fluid pressure is connected to the downstream side of the flow path of the valve mechanism and when the left and right traveling In order to merge the fluid from the pump for driving the earth removal work equipment to the fluid pressure motor for left and right travel, such as when the fluid from the pump for driving the work equipment is joined to the downstream side of the flow path from the control valve for the fluid pressure motor. It is also advantageous in that the two pipings are not required and piping can be omitted.

Hereinafter, embodiments of the present invention will be described based on the drawings.

As shown in Figures 1 and 2, the hydraulic motor
A rotating base 2 is mounted on a traveling machine base equipped with a pair of left and right traveling crawlers 1a and 1b that can be driven separately at Ma and Mb.
is mounted so that it can be driven and rotated around the vertical axis _X1 by a hydraulic motor Mc, an engine 3 is mounted on the rear of the swivel base 2, and a cabin 5 with a driver's seat 4 is mounted on the left side of the swivel base 2. A bracket 7 for supporting the backhoe device 6 is attached to the horizontal center of the front side of the swivel base 2 so that it can be driven and oscillated around the vertical axis _X2 by a hydraulic cylinder 8.
, the boom 9 is installed so that it can be driven up and down around the horizontal axis by a hydraulic cylinder 10, and the boom 9 is
The arm 11 is attached to the arm 11 so as to be swingable around the horizontal axis by a hydraulic cylinder 12, and the bucket 13 is attached to the arm 11 so as to be swingable around the horizontal axis by the hydraulic cylinder 14. A support arm 16 for an earth removal plate 15 as an earth removal work device is attached to the front part of the table so that it can be moved up and down by a hydraulic cylinder 17, and can also be used as a dozer that can perform dozer work and backhoe work. It is configured as a backhoe work vehicle.

For driving the various hydraulic actuators, a second
As shown in the figure, two main pumps Pa, Pb and 1
Auxiliary pumps Pc are provided directly connected to the engine 3,
One main pump Pa has a control valve V ₁ for the hydraulic motor Ma for the left running roller 1a, a control valve V ₂ for the hydraulic motor Mc for the swivel base 2, a control valve V ₃ for the arm hydraulic cylinder 12, and a boom. A state in which the speed-increasing drive control valves V ₄ of the hydraulic cylinders 10 are connected in parallel, and pressure oil from the one main pump Pa is directly supplied to these control valves V ₁ . A merging valve _V5 is provided as a shift valve mechanism for switching the pressure oil from the main pump Pb to the pressure oil of the other main pump Pb.
The right traveling crawler 1b is connected to the other main pump Pb.
Connect the control valve V ₆ of the hydraulic motor Mb to the right motor Mb, and connect each of the control valve V ₇ of the bucket cylinder 14 and the control valve V ₈ of the boom cylinder 10 to the right motor control valve V ₆ . The pressure oil is connected in parallel so that the control valve V ₉ for speed increasing drive of the arm cylinder 12 is supplied to the control valve V ₇ for the bucket and the control valve V ₈ for the boom in their neutral state. They are connected in parallel so that they can be supplied. Furthermore, the control valve _V10 of the bracket cylinder 8 and the control valve _V11 of the earth removal plate cylinder 17 are connected in parallel to the auxiliary pump Pc.

By operating the merging valve _V5 , the first state in which pressure oil from both main pumps Pa and Pb is separately supplied to both motors Ma and Mb, and the combined fluid from both main pumps Pa and Pb are both changed. The configuration is such that it is possible to adopt a traveling drive mode according to various work situations while switching to the second state in which the power is supplied to the motors Ma and Mb.

However, 18 in the figure is a rotary joint.

Further, the pressure oil discharged in the neutral state from the control valve V ₁₀ for operating the bracket and the control valve V ₁₁ for operating the earth removal plate is supplied to the main pump for the right traveling crawler 1b via the flow path R ₁ . Pb discharge flow path
A _{flow path opening/closing valve V 12 as a merging valve mechanism for opening and closing the merging supply flow path R 1 is} provided so as to be operable simultaneously with the merging valve V ₅ . In the second state, the fluid from the auxiliary pump Pc is combined with the fluid from the two main pumps Pa and Pb so that the fluid can proceed at a sufficiently high speed.

Next, another example will be described.

The flow path opening/closing valve 12 for the auxiliary pump Pc described in the above embodiment may be provided in a freely operable manner separately from the merging valve _V5 . In other words, if this configuration is adopted, in addition to the 2-speed high and low speed change using the merging valve _V5 ,
The opening/closing valve _V12 allows the vehicle to be shifted one more step, and the traveling speed can be changed to three steps.

The present invention is applicable not only to dozer-cum-backhoe work vehicles, but also to dozer-only work vehicles, backhoe work vehicles, and the like. In other words, the present invention can be applied to various work vehicles equipped with two fluid pressure pumps Pa and Pb for traveling and a fluid pressure pump Pc for driving the work equipment. The configuration of the valve mechanism _V5 for switching between the first and second states can be changed in various ways, and the configuration of the valve mechanism _V12 for supplying the fluid from the working device driving pump Pc to the combined fluid can also be changed in various ways.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the fluid pressure circuit of a backhoe with an earth removal device according to the present invention, and FIG. 1 is a side view of the backhoe working vehicle, and FIG. 2 is a circuit diagram. 1a, 1b...Traveling device, Ma, Mb...Fluid pressure motor, Pa, Pb...Fluid pressure pump for traveling drive,
Pc...Fluid pressure pump, V5...Speed valve mechanism,
V12... Merging valve mechanism, R1... Merging supply channel, 2, 9, 11, 13... Working device, Mc, 1
0, 12, 14...Fluid pressure actuator, 15
...Earth removal work equipment.

Claims (1)

[Scope of Claim for Utility Model Registration] Two fluid pressure pumps Pa and Pb are provided for driving fluid pressure motors Ma and Mb respectively attached to the left and right traveling devices 1a and 1b, and these pumps Pa and Pb are provided.
One of the pumps Pa is connected to one of the traveling devices 1a.
The fluid pressure motor Ma for the traveling device 1b is connected to the other pump Pb, and the fluid pressure motor Mb for the other traveling device 1b is connected to the other pump Pb. In a fluid pressure circuit of a backhoe equipped with an earth removal device that is provided with a fluid pressure pump Pc for driving the working device 15, fluid from the pumps Pa and Pb is supplied to the fluid pressure circuit to the left and right traveling devices 1a and 1b. A shift valve that switches between a first state in which the left and right traveling devices 1a and 1b systems are supplied separately, and a second state in which the combined fluid from the pumps Pa and Pb is serially supplied to the left and right traveling devices Ma and Mb systems. A mechanism V5 is provided, and the fluid from the fluid pressure pump Pc for the earth removal work device 15 is connected to the fluid pressure circuit to the earth removal work device 15 to join the combined fluid when the earth removal work device 15 is not in use. A soil removal device is provided with a merging valve mechanism V12 for switching to a supply state, and further has a merging supply flow path R1 from the valve mechanism V12 connected to the upper side of the flow path than the speed change valve mechanism V5. Fluid pressure circuit for backhoe.