JPS6230308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a regulator for controlling the capacity of a so-called double tilting variable capacity hydraulic pump in which the discharge direction can be set on both sides.

Conventional regulators for controlling the capacity of variable displacement hydraulic pumps include one with a structure shown in FIG. 1 and one with a structure shown in FIG. 2. In the one shown in FIG. 1, when the operating lever is operated in the direction of the arrow, the spool of the regulator 4 is switched via the links 2 and 3, and the pressure oil from the hydraulic source 5 is passed through the pipe 6 or 7 to the variable displacement hydraulic pump 8. one swash plate 9 control actuator (piston) 10 or 11, and the other actuator to the oil tank 1.
2 to move the swash plate 9. Since the spool of the regulator 4 is connected to the swash plate 9 via the link 3, the amount of tilting of the swash plate 9 is controlled by the operating lever 1.
When the amount of tilt corresponding to the movement of the spool is reached, the spool returns to the neutral position and the swash plate 9 is held in that position, that is, the structure is such that a flow rate proportional to the amount of operation of the operating lever 1 is obtained. On the other hand, the variable displacement hydraulic pump 8 generates an amount of oil commensurate with the amount of tilting of the swash plate 9, and the amount of oil is
3 or 14 to act on the actuator (hydraulic motor) 15 to drive it.

In the above regulator, the hydraulic motor 15
The rotational speed of is proportional to the amount of operation of the operating lever 1, but when the load of the inertial load 16 connected to the hydraulic motor 15 is large and the pressure in the pipe 13 or 14 becomes high, the crossover relief valve 17 or 18 It opens to allow pressure oil from the high pressure side to flow to the low pressure side, protecting the circuit. The energy of the oil passing through the relief valve becomes lost energy and increases the temperature of the hydraulic oil.

2, the spool of the regulator 4 is connected only to the operating lever 1 via the link 19, and the pressure in the pipes 13 and 14 of the variable displacement hydraulic pump 8 is connected to the pilot pipes 20 and 21, respectively.
This structure provides feedback to both ends of the spool through the spool. That is, when operating the operating lever 1,
The regulator 4 causes pressure oil from the hydraulic source 5 to flow into the actuator 10 or 11 for controlling the swash plate 9 of the variable displacement hydraulic pump 8 via the pipe 6 or 7 according to the amount of operation thereof. The flow rate increases until pressure from pilot line 20 or 21 is fed back to the spool. When the pressure in the pipe 13 or 14 becomes higher than the pressure corresponding to the amount of operation of the operating lever 1, the pilot pipe 20 or 2
The spool of the regulator 4 is switched in the opposite direction by the pilot pressure fed back from the piping 6 or 7, thereby reducing the flow rate of the pressure oil flowing into the pipe 6 or 7. In the figure, 12 is an oil tank, 15 is an actuator, and 16 is an inertial load.

By the way, in construction machinery, the regulator shown in FIG. 1, which controls the speed of an actuator such as a hydraulic motor by the amount of operation of a control lever, is generally used. However, in the regulator shown in Figure 1,
As mentioned above, when the pressure in the circuit to the actuator exceeds the set pressure of the relief valve, there is a drawback that the energy of that pressure is dissipated via the relief valve. In addition, in the regulator shown in Fig. 2,
Although the above drawbacks can be solved, there is a drawback that the speed of the actuator changes depending on the pressure in the circuit, making it difficult to operate the actuator.

In order to solve the above-mentioned drawbacks, the present invention operates as a regulator for controlling the tilting amount of a variable displacement hydraulic pump when the pressure in the circuit is below the relief pressure, and as a pressure control regulator when it is above the relief pressure. An object of the present invention is to provide a regulator for controlling the capacity of a variable capacity hydraulic pump.

In the present invention, pressure receiving chambers are provided in the valve housing at both ends of the spool, the spool is displaced by the pressure in the pressure receiving chambers, and a port leading to a hydraulic power source is provided between the outer periphery of the land of the spool and the valve housing. A sleeve having a port leading to an actuator that controls a tilting mechanism that changes the capacity of the variable displacement hydraulic pump and a port leading to an oil tank is provided so as to be slidable relative to the spool, and the sleeve and the tilting mechanism are linked. The displacement of the operating lever is transmitted to the link, the displacement of the tilting mechanism and the position of the sleeve are determined using the transmission point as a fulcrum, and the actuator is controlled by the land of the spool, and the hydraulic The pressure of the two ports of the pump is guided to the pressure receiving chamber and the oil tank through relief valves, a restriction is provided between the relief valve and the oil tank, and when the relief valve opens, oil flows into the oil tank. When this happens, the spool is moved to a position balanced with the return spring by the increase in pressure caused by the throttle, and the position of the tilting mechanism is controlled by this movement.

Hereinafter, one embodiment of the capacity control regulator of the variable displacement hydraulic pump of the present invention will be described with reference to FIG. In the figure, reference numeral 22 denotes a double tilting variable displacement hydraulic pump, whose volume per revolution is given by the amount of tilting of a swash plate 23, which is controlled by pistons 24 and 25. Reference numeral 26 denotes a hydraulic motor for driving the inertial body 27. The hydraulic motor 26 is connected to the two ports 28 and 29 of the hydraulic pump 22 via piping 30 and 31, respectively.
It is driven by the amount of oil discharged from 2. 32 is a regulator, and the regulator 32 has a valve housing 34 provided with pressure receiving chambers 33a and 33b at both ends, and a pressure receiving pin 3 due to the pressure of the pressure receiving chambers 33a and 33b.
5 and 36, and a return spring 38 that returns the spool 37 to its original position.
and a sleeve 39 that is provided between the outer periphery of the land of the spool 37 and the valve housing 34 and is slidable relative to the spool 37. The sleeve 39 also has a port 41 communicating with the hydraulic power source 40 and a piston 2 for controlling the swash plate of the hydraulic pump 22.
It has ports 44, 45 that can communicate with piping 42, 43 that communicate with the oil tanks 4, 25, and ports 47, 48 that can communicate with an oil tank 46. Further, the sleeve 39 is connected to the swash plate 23 of the hydraulic pump 22 via a link 49, and the link 49 is connected to an operating lever 51 via a rod 50. 52 is a pipe that communicates with the pipe 30 of the hydraulic pump 22, and the pipe 52 has a relief valve 53 in the middle thereof and communicates with the pressure receiving chamber 33a of the regulator 32 and the oil tank 46, and also connects the oil tank 46 and the relief valve 53. A diaphragm 54 is provided between the two.
55 is a pipe that communicates with the pipe 31 of the hydraulic pump 22, and the pipe 55 has a relief valve 56 in the middle to communicate with the pressure receiving chamber 33b of the regulator 32 and the oil tank 46, and also connects the oil tank 46 and the relief valve 56. A diaphragm 57 is provided between the two.

Next, the operation of the control regulator of the variable displacement hydraulic pump of the present invention will be explained. In FIG. 3, the operating lever 51 is in the neutral position and the swash plate 23 of the hydraulic pump 22 is also in the neutral position. From this state, when the operating lever 51 is moved in the direction of the arrow as shown in FIG. 4, the displacement is transmitted to the link 49 via the rod 50. At this time, since the swash plate 23 of the hydraulic pump 22 connected to the link 49 is held by the pistons 24 and 25, the link 49 pushes the sleeve 39 leftward using the connection point A of the swash plate 23 as a fulcrum. As a result, the pressure oil from the hydraulic source 40 flows into the pipe 43 from the port 41 through the port 44 and acts on one of the swash plate control pistons 24 of the hydraulic pump 22. Also, the oil in the other piston 25 is in the pipe 4
2, port 45, and is returned to oil tank 46 from port 47. Therefore, the swash plate 23 of the hydraulic pump 22 is tilted counterclockwise and operated to increase the amount of discharge into the pipe 30. When the swash plate 23 is tilted, the link 49 is rotated about the connection point B with the rod 50, and the sleeve 39 is moved to the right. And finally ports 44 and 45 are connected to spool 3
7, the swashplate control pistons 24 and 2
5 is fixed, and the swash plate 23 is held in that position. That is, the swash plate 2 is adjusted to the value specified by the operating lever 51.
3 is retained.

When the pressure in the discharge side piping 30 of the hydraulic pump 22 becomes higher than the set pressure of the relief valve 53 while the hydraulic motor 26 is being driven by controlling the tilting of the swash plate 23 of the hydraulic pump 22 as described above, the first As shown in FIG. 5, the relief valve 53 opens and oil flows into the pipe 52. Before the oil reaches the oil tank 46, the pressure is increased by the throttle 54, and the pressure in the pressure receiving chamber 34 increases, which is transmitted to the pressure receiving pin 36, and the spool 3
7 is pushed to the left until it balances with the spring force of the return spring 38. Therefore, the pressure oil from the hydraulic source 40 acts on the swash plate control piston 25 via the port 45 and the piping 42, and the other piston 24 side acts on the piping 42.
3. It is connected to the oil tank 46 through ports 44 and 48, and the swash plate 23 is tilted clockwise.
Port 44 is connected to spool 37 using the same movement as described above.
45 is closed, the swash plate 23 is held, and the discharge amount of the hydraulic pump 22 is reduced to prevent relief. Then, when the relief valve 53 closes,
The pressure in the pipe 52 decreases, and the spool 37 returns to the right side due to the spring force of the return spring 38. With the same movement as described above, the piston 24 connects to the hydraulic pressure source 40, the piston 25 connects to the oil tank 46, and the spool 37 connects to the swash plate 23.
is tilted counterclockwise and returns to the position instructed by the operating lever 51 again.

The above is an explanation of the operation when the relief pressure is reached when driving the load. Next, the case where the hydraulic pump 22 is driven by the motor action due to the inertia of the load will be explained using FIG. 3. When the pressure in the suction side piping 31 increases and the relief valve 56 opens, the pressure receiving chamber is The pressure of 33b increases and the spool 3
Push 7 to the right. As a result, the piston 24 communicates with the oil pressure source 40, and the piston 25 communicates with the oil tank 46, respectively, and tilts the swash plate 23 counterclockwise to increase the discharge amount per revolution of the hydraulic pump 22. The pressure in the pipe 31 is reduced.

As described above, the capacity control regulator of the present invention, when controlling the actuator by the discharge amount of the double tilting variable displacement hydraulic pump, maintains the circuit pressure regardless of the load state, no matter what operation the operator performs. When the circuit pressure exceeds the overload relief pressure, the discharge amount is adjusted so that the circuit pressure becomes below the relief pressure, reducing energy loss due to overload relief, and when the circuit pressure is below the overload relief pressure, the flow rate is proportional to the amount of lever operation. This has the effect of making it easier to operate the actuator.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit diagrams showing a regulator for controlling the capacity of a conventional variable displacement hydraulic pump;
The figure is a cross-sectional view showing one embodiment of the capacity control regulator of the variable displacement hydraulic pump of the present invention, and FIGS. 4 and 5 are cross-sectional views showing the operation of the regulator of the present invention. 22...variable displacement hydraulic pump, 23...swash plate,
24, 25... Swash plate control piston, 26... Hydraulic motor (actuator), 28, 29... Port, 30, 31, 42, 43, 52, 55...
Piping, 32... Regulator, 33a, 33b...
... Pressure receiving chamber, 34 ... Valve housing, 35, 36 ... Pressure receiving pin, 37 ... Spool, 38 ... Return spring, 39 ... Sleeve, 40 ... Hydraulic pressure source, 41,
44, 45, 47, 48...port, 46...oil tank, 49...link, 50...rod, 51
...Operation lever, 53, 56...Relief valve, 5
4,57'...diaphragm, 58...valve housing.

Claims (1)

[Claims] 1. In a capacity control regulator for a so-called double tilting variable displacement hydraulic pump in which the discharge direction can be set on both sides, pressure receiving chambers are provided in the valve housing at both ends of the spool, and the spool is displaced by the pressure in the pressure receiving chambers. and between the outer circumference of the land of the spool and the valve housing, there is provided a sleeve having a port leading to a hydraulic power source, a port leading to an actuator that controls a tilting mechanism that changes the capacity of the hydraulic pump, and a port leading to an oil tank. The sleeve is provided to be slidable on the spool, and the sleeve and the tilting mechanism are connected by a link, and the displacement of the operating lever is transmitted to the link, and the displacement of the tilting mechanism and the sleeve are connected using the transmission point as a fulcrum. the actuator is controlled by the land of the spool, and the pressure of two ports of the hydraulic pump is guided to the pressure receiving chamber and the oil tank via relief valves, respectively, and the pressure of the actuator is controlled by the land of the spool. A throttle is provided between them, and when the relief valve opens and oil flows into the oil tank, the increase in pressure caused by the throttle moves the spool to a position where it balances the return spring, and this movement changes the position of the tilting mechanism. A regulator for controlling the capacity of a variable capacity hydraulic pump, characterized in that it is configured to control.