JPS6344260Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a traveling hydraulic circuit used in a self-propelled vehicle such as a self-propelled aerial work vehicle.

Conventionally, in self-propelled vehicles equipped with hydraulic motors that drive the left and right wheels, the left and right wheels always rotate at the same speed, so there is no problem when driving straight, but even when the vehicle turns, the left and right wheels do not rotate at the same speed. The problem was that the wheels would slip, making it difficult to turn smoothly.

This invention was developed in view of the above circumstances, and by differentially driving the left and right wheels when the vehicle is turning, it is possible to perform the turn smoothly, and when one wheel is lifted, the left and right wheels are The object of the present invention is to provide a travel hydraulic circuit that can always run smoothly by rotating the wheels at the same speed.

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the discharge pipe 18 of the pump 2 is connected to the switching valve 3, and the pipes 19, 20, 2
The left and right traveling hydraulic motors 6 and 7, which are connected in parallel by 1 and 22, and the switching valve 3 are connected by conduits 4 and 5. A diverting valve 23 is inserted into the connecting portion connecting the conduit 5 and the conduits 20 and 21 to distribute an equal amount of pressure oil to both the hydraulic motors 6 and 7 connected in parallel. It may also be inserted into a connecting portion that connects the pipes 19 and 22.

A pipe that supplies pressure oil to the hydraulic motor that drives the outer wheels, which have less load, than a pipe that supplies pressure oil to the hydraulic motor that drives the inner wheels, which have a higher load, when the vehicle turns right or left. Pressure oil flows through the road to differentially drive the left and right wheels, and when the right or left wheel floats, the load is removed from a pipe that supplies pressure oil to the hydraulic motor that drives the wheel that is not floating, which has a large load. In order to prevent pressure oil from flowing into the pipes that supply pressure oil to the hydraulic motors that drive the wheels that are slightly floating, and to rotate the left and right wheels at the same speed, the pipes 19 and 22 and the pipes 20, 21
The ports are connected in opposite directions through a pair of 2-port, 2-position pilot switching valves 8, 9, 10, and 11, each equipped with a check valve, and the outlet of each pilot switching valve 8, 9, 10, and 11 is connected in the opposite direction. Throttle valves 12, 13, 14, 15 are provided on each side, and each pilot switching valve 8, 9, 10, 11 is connected to a pilot pipe so that pilot pressure is taken from both sides of the pilot switching valve 8, 9, 10, 11. establish a road,
Each pilot switching valve 8, 9, 10, 11
are normally held at the a position to allow communication between the pipes 19 and 22 and between the pipes 20 and 21 via check valves, and the respective switching valves 8, 9, 1
When the pressure difference generated before and after each throttle valve 12, 13, 14, 15 exceeds a certain value due to an increase in the amount of pressure oil flowing through 0, 11, each pilot switching valve 8, 9, 10, 11 moves to position b. The communication between the pipes 19 and 22 or between the pipes 20 and 21 is cut off.

With the above configuration, when the switching valve 3 is switched from the neutral position b to the running position a or c, the pressure oil discharged from the pump 2 passes through the switching valve 3 to the pipe 4 and the pipes 19, 22 or the pipe 5. The same amount is supplied to both traveling hydraulic motors 6 and 7 through conduits 20 and 21. When the vehicle is traveling straight, the load applied to both hydraulic motors 6 and 7 is the same, so the pilot switching valves 8 and 9 or the pilot switching valve 1
Since no pressure oil flows through motors 0 and 11, both hydraulic motors 6 and 7 rotate at the same speed.

Also, when the vehicle turns to the left, a large load is applied to the hydraulic motor 6 that drives the left wheel, which is the inner wheel, and a load is applied to the hydraulic motor 7, which drives the right wheel, which is the outer wheel. As a result, the pressure in the pipe 22 or pipe 21 that supplies pressure oil to the left hydraulic motor 6, which is subject to a large load, is reduced to the pipe 19 or pipe 21 that supplies pressure oil to the right hydraulic motor 7, which has a small load. The pressure becomes higher than the pressure inside the pipe 20, and the pressure increases from the pipe 22 or the pipe 21 to the pipe 19.
Alternatively, pressure oil flows into the pipe line 20 via the pilot switching valve 8 or pilot switching valve 11, and the amount of pressure oil flowing to the right hydraulic motor 7 becomes larger than the amount of pressure oil flowing to the left hydraulic motor 6. The hydraulic motor 7 rotates faster than the left hydraulic motor 6, and the left and right wheels are differentially driven, allowing the vehicle to turn smoothly to the left without the wheels slipping. When the vehicle turns to the right, the hydraulic motor 7 drives the right wheel, which becomes the inner wheel when turning to the right.
A large load is applied to the hydraulic motor 6 on the left side, which is the outer wheel, and there is a difference in load between the hydraulic motor 6 on the left side and the hydraulic motor 7 on the right side on which a large load is applied.
The pressure in the pipe line 19 or pipe line 20 that supplies pressure oil to Line 20 to Line 2
2 or through the pilot switching valve 9 or pilot switching valve 10 to the pipe line 21, and the amount of pressure oil flowing to the left hydraulic motor 6 is larger than the amount of pressure oil flowing to the right hydraulic motor 7, so that the left side The hydraulic motor 6 rotates faster than the right hydraulic motor 7, and the right and left wheels are differentially driven, allowing the vehicle to turn smoothly to the right without the wheels slipping. In addition, the difference in load between the left and right hydraulic motors 6 and 7 increases due to the left wheel floating, etc., and the amount of pressure oil flowing through the pilot switching valve 9 or 10 increases, causing the throttle valve 13 or 14 to increase. When the pressure difference generated before and after exceeds a certain value, the pilot switching valve 9 or the pilot switching valve 10 is switched from the a position to the b position, and communication between the pipes 19 and 22 or between the pipes 20 and 21 is cut off. , the amount of pressure oil flowing to both hydraulic motors 6 and 7 becomes equal, the right wheel that is not floating is driven, and the vehicle can run smoothly. As the right wheel floats, etc., the difference in load between the left and right hydraulic motors 7 and 6 increases, and the amount of pressure oil flowing through the pilot switching valve 8 or pilot switching valve 11 increases, causing the front and back of the throttle valve 12 or 15 to increase. When the pressure difference generated between the
position, the communication between the pipes 22 and 19 or between the pipes 21 and 20 is cut off, the amount of pressure oil flowing to both hydraulic motors 6 and 7 becomes equal, and the left wheel that is not floating is driven, and the vehicle can run smoothly.

As described above, according to the present invention, there is provided a travel hydraulic circuit that can differentially drive the left and right wheels when turning, and can prevent the vehicle from being unable to travel due to the floating wheel idling when one wheel floats. provided,
The present invention is effective in improving the running performance of self-propelled vehicles that run using hydraulic pressure.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 shows a travel hydraulic circuit. 6, 7...Hydraulic motor for traveling, 8, 9, 10,
11... Pilot switching valve, 12, 13, 14,
15... Throttle valve, 19, 20, 21, 22... Pipe line, 23... Diversion valve.

Claims (1)

[Scope of utility model registration request] The travel hydraulic motors that drive the left and right wheels are connected in parallel via a diversion valve, and a pair of pipes are connected in opposite directions through pilot switching valves each equipped with a check valve between the pipes of the left and right hydraulic motors. A throttle valve is provided on the outlet side of each pilot switching valve, and each pilot switching valve takes pilot pressure from both sides of the pilot switching valve, so that normally the pipes of both hydraulic motors are communicated with each other. However, when the pressure difference generated before and after the throttle valve exceeds a certain value due to an increase in the amount of pressure oil flowing through the pilot switching valve, the pilot switching valve is switched.
A travel hydraulic circuit characterized in that communication between pipes of both hydraulic motors is cut off.