JPS6220256Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a driving device for a barrel containing concrete in a concrete mixer truck.

As shown in the first diagram, a conventional drive device of this type has a hydraulic motor a that rotates a barrel i in forward and reverse directions, and a closed circuit b.
Generally, a double-discharge type variable displacement hydraulic pump c is connected through the closed circuit b, and a fixed displacement replenishment pump d is connected to replenish the fluid in the closed circuit b, and the flow rate of the closed circuit b and its flow are The direction of the control piston e of the variable displacement hydraulic pump c is connected to the servo valve f,
It is controlled by controlling the valve g and the joystick valve h. The variable displacement hydraulic pump c and the replenishment pump d are the driving motor j of the mixer truck.
Therefore, when the prime mover j is in an idling state, the replenishment amount of the replenishment pump d is likely to be insufficient, and there is a risk of cavitation in the closed circuit b, and the oil temperature is likely to rise due to the replenishment pump d, which is undesirable. Furthermore, even if the control piston e is controlled to reduce the discharge amount to zero, the variable displacement hydraulic pump c still discharges some fluid into the closed circuit b, so it is inconvenient that the hydraulic motor a cannot be completely stopped. be.

The purpose of this invention is to solve the inconveniences and inconveniences of such a barrel drive device.The purpose of this invention is to connect the barrel A of a concrete mixer truck to a hydraulic motor 2 driven by a variable displacement hydraulic pump 1 for forward and reverse rotation. , the discharge circuit 3 and suction circuit 4 of the variable displacement hydraulic pump 1 are connected to the operating circuits 6 and 7 of the hydraulic motor 2 via a spool-type switching valve 5 having a flow rate adjustment function, A replenishment circuit 9 connected to a tank 8 is connected to the suction circuit 4.

An embodiment of the present invention is shown in the second figure, in which the switching valve 5 is connected to a discharge circuit 3 and a suction circuit 4.
and a neutral position 5 that interrupts communication with the operating circuits 6 and 7.
a, a switching position 5b connected to the discharge circuit 3 and the suction circuit 4 operating circuits 6 and 7 in forward and reverse directions and connected to the hydraulic motor 2 to perform forward rotation for sucking concrete and reverse rotation for concrete discharge; 5c, and a low rotation position 5d provided with a throttle to rotate the hydraulic motor 2 normally at a relatively low speed when the mixer truck is running.
The opening area is changed according to the moving distance at the intermediate position between the two positions, and the flow rate adjustment function is performed by distributing the corresponding flow rate. I made it. Further, the variable displacement hydraulic pump 1 has a swash plate and other means for varying its displacement operated by control pistons 11 and 12 that move in opposite directions. In this case, the pressure of the discharge circuit 3 is introduced into one control piston 11, and the other control piston 12 has a larger pressure receiving area than the control piston 11, and the pressure of the discharge circuit 3 is introduced therein via the servo valve 13. Alternatively, tank pressure is introduced selectively, and when the pressure of the discharge circuit 3 acts on both pistons 11 and 12, the control piston 12, which has a large pressure-receiving area, directs means such as a swash plate in the direction of decreasing the discharge amount. The control piston 11 is tilted against the spring 11a, and when tank pressure acts on the control piston 12, the pressure of the discharge circuit 3 acting on the other control piston 11 causes the control piston to move in the direction of increasing the discharge amount. It is made to tilt against 12 springs 12a. Further, when the pressure in the discharge circuit 3 exceeds a set pressure, the servo valve 13a introduces the pressure to the control piston 12 to reduce the pump discharge amount and prevent waste of pump power.
When the pressure in the discharge circuit 3 exceeds the sum of the higher pressure in the operating circuits 6, 7 extracted via the shuttle valve 16 and the force of the spring 14, the pilot circuit 15 to the control piston 12 is activated. and a second servo valve 13b connected to the tank to increase the pump discharge amount.

In the device of the present invention, when the switching valve 5 is in the neutral position 5a shown in the figure, the operating circuits 6 and 7 are not connected to the discharge circuit 3 and the suction circuit 4, and the hydraulic motor 2 and the barrel A are connected to each other.
The rotation of the hydraulic pump 1 is stopped, and the hydraulic pump 1 is closed to the servo valve 1.
3, the discharge amount is automatically controlled to zero. The switching valve 5 changes from the neutral position 5a to the switching position 5b.
Or, when it is slid in the direction 5c, the connection area between the operating circuits 6, 7, the discharge circuit 3, and the suction circuit 4 gradually increases, and the rotational speed of the hydraulic motor 2 and the barrel A gradually increases. In this case, the flow rate that is insufficient due to oil leakage in the circuit, etc. is self-suctioned by the hydraulic pump 1 via the replenishment circuit 9, so even if the prime mover 17 of the mixer truck that drives the pump 1 is in an idling state and the rotation speed drops, there will be no shortage of flow. You can continue to replenish the amount.

In this way, the present invention connects the operating circuits 6 and 7 of the hydraulic motor 2 that rotates the barrel A to the discharge circuit 3 and suction circuit of the variable displacement hydraulic pump 1 via the spool-shaped switching valve 5 having a flow rate adjustment function. 4, the barrel A can be stopped by operating the switching valve 5, preventing unnecessary consumption of power, and the suction circuit 4 is connected to the tank 8 via the replenishment circuit 9. Therefore, the insufficient flow rate in the circuit can be automatically replenished, and the drawbacks of replenishing with a conventional replenishment pump can be overcome.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a conventional barrel drive device, and FIG. 2 is a diagram of an embodiment of the present invention. A... Barrel, 1... Variable displacement hydraulic pump,
2... Hydraulic motor, 3... Discharge circuit, 4... Suction circuit, 5... Switching valve, 6, 7... Operating circuit, 8...
...tank, 9...replenishment circuit.

Claims (1)

[Scope of utility model registration request] The barrel A of a concrete mixer truck is connected to a hydraulic motor 2 driven by a variable displacement hydraulic pump 1 for forward and reverse rotation, and the discharge circuit 3 and suction circuit 4 of the variable displacement hydraulic pump 1 are connected to a hydraulic motor 2 driven by a variable displacement hydraulic pump 1. is connected to the operating circuits 6 and 7 of the hydraulic motor 2 via a spool-shaped switching valve 5 having a flow rate adjustment function, and a replenishment circuit 9 connected to a tank 8 is connected to the suction circuit 4. barrel drive.