JPS5926796B2 - Regulator circuit of variable displacement hydraulic pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a regulator circuit for a variable displacement cedar hydraulic pump driven by an engine.

The regulator of a variable displacement cedar hydraulic pump driven by an engine is generally set so as to move along the Erohani line shown in FIG.

Here, the Rohm curve represents a constant hydraulic power curve, and this curve is equal to the maximum output of the engine.

In other words, in Figure 1, as the load increases, the pressure in the circuit increases, and when it reaches the point A, the engine output reaches its maximum value, and when the load pressure increases further beyond the point A, the hydraulic output increases. In order to prevent the pressure from becoming larger than the engine output, the regulator is operated to reduce the discharge amount of the hydraulic pump, and the horse power to low moves on a constant curve and reaches the relief pressure point C. .

The operation of this regulator will be explained in more detail using FIG.

In FIG. 2, 1 is an engine, and this engine 1 is equipped with a flywheel 1a for reducing torque fluctuations.

2 is a variable displacement cedar hydraulic pump, 3 is a cylinder, 4 is a piston, 5 is a housing, 6 is a sleeve, 1 is a spool, 8
1 is a rod, 9 is a pressure receiving pin, 10 is a spring, 13 is a hydraulic pressure source, 14.15 is a conduit, 16 is a time delay mechanism, 11 is a strainer, and 18 is a tank.

The time delay mechanism shown in FIG. 2 is composed of a throttle 16a, an accumulator 16b, and a check valve 16c.

At S in FIG. 2, when the load increases and the pressure in the main circuit 12 rises, the pressure passes through the conduit 11 to the pressure receiving pin 9.
spool 7 until it balances the force of spring 10.
Move to the left side of the diagram.

Therefore, the pressure oil from the hydraulic source 13 is transferred to the port 6 of the sleeve 6.
It flows from pipe 15 to cylinder 3 via port a, and pipe 14 leads to tank 18 via port 6c.

Therefore, the piston 4 moves to the right in the figure, and the rod 8 is moved in a direction that reduces the discharge amount of the hydraulic pump 2.

At the same time, the sleeve 6 moves to the left in conjunction with the rod, the spool 1 closes the ports 6a and 6b, and the piston 4 is held in that position.

When the pressure in the main circuit 12 decreases, the pressure acting on the pressure receiving pin 9 decreases, and the force of the spring 10 causes the spool 6 to
is moved to the right side of the figure, port 6b communicates with tank 18, and port 6c communicates with hydraulic source 13.

Therefore, the piston 4 moves to the left in the figure, and the rod 8 moves in the direction of increasing the discharge amount of the hydraulic pump 2.

Further, the movement of the rod 8 causes the sleeve 6 to move to the right, and the spool 7 closes the ports 6b and 6c to hold the piston 4 in that position.

In this way, the variable hydraulic pump has a mechanism that allows it to move on the constant horse curve Loha shown in Figure 1. In conventional variable hydraulic pumps driven by an engine, these movements are dependent on the discharge pressure. It is configured to work immediately in response to the engine pressure and to prevent the hydraulic output from exceeding the engine output.

By the way, engines are generally equipped with a flywheel, albeit a small one, in order to reduce torque fluctuations, and when considering all rotating parts such as the crankshaft, there is considerable inertial mass, and this is stored as rotational energy. ing.

Focusing on the rotational energy possessed by the engine itself as described above, in order to effectively utilize the stored rotational energy when a force greater than the engine output is momentarily required, from circuit 12) to Uzing 5. The conduit 11 leading thereto is equipped with a time delay mechanism 16.

In this way, when the pressure in the main circuit 12 increases, the pressure is transmitted to the pipe line 11, but this pressure does not immediately act on the pressure receiving bottle 9 of the housing 5, but instead
It acts on the pressure receiving bottle 9 of the housing 5 after a certain delay time set depending on the diameter of the accumulator 16b, the capacity of the accumulator 16b, or the sealing pressure.

Therefore, the behavior of the hydraulic pump is as shown by the dotted line in FIG.

In other words, when the pressure increases from point A, it reaches the point A, but because of the time delay mechanism 16, the discharge amount does not decrease even at this point, and reaches the load pressure point, and after a certain time delay, the discharge amount decreases. The horse power decreases and reaches a point on the constant curve.

FIG. 3 shows another example having a time delay mechanism.

In this example, when the pressure in main circuit 12 increases, conduit 1
1, the pressure oil from the hydraulic source 13 is conducted to the cylinder 3, but since there are throttles 20 and 21 in the pipes 14 and 15, the piston 4 moves slowly. This is designed to cause a delay.

In this case, although the diagram shows a case in which a throttle is used in both the conduits 14 and 15, it is also possible to use a throttle only on one side.

The regulator circuit of the conventional variable displacement cedar hydraulic pump as described above operates with a time delay after the discharge pressure rises, thereby adding the rotational energy due to the inertial mass of the rotating parts of the engine to the engine output and generating an instantaneous output. However, since the hydraulic pump driven by the engine operates at various rotational speeds, the amount of energy available varies depending on the rotational speed, and a certain time delay mechanism is required. In this case, the rotational energy of the engine cannot be fully utilized.

In other words, if a time delay mechanism adjusted for high speed rotation is used during low speed rotation, the delay time will be too large and there is a risk of engine stoppage.On the other hand, if the time delay mechanism is adjusted to be suitable for low speed rotation, the time delay mechanism will be delayed during high speed rotation. Energy cannot be fully utilized.

The present invention aims to improve such inconveniences, and as shown in FIG. A control mechanism for controlling the delay time of the time delay mechanism 16 is provided.

That is, in the case of this embodiment, the rotational speed detection device 19 is a device that generates oil pressure proportional to the rotational speed, and the aperture of the time delay mechanism 16 is set to the variable aperture 16a, and the lever that changes the amount of aperture is set to the rotation speed. A cylinder 16e connected to the number detection device 19 is coupled, and a spring 16d opposing the cylinder 16e is provided.

In this way, oil pressure proportional to the engine rotation speed is generated from the rotation speed detection device 19, and this is generated in the cylinder 16e.
The variable throttle is automatically adjusted to a point where the pressure is balanced with the spring 16d.

Therefore, when the engine speed is high, the aperture of the throttle becomes small, and when the engine speed is low, the aperture of the aperture becomes large, so that the delay time can be automatically adjusted.

Of course, this delay time is set to a value that allows effective extraction of rotational energy depending on the size and rotational speed of the rotating mass such as the engine.

As described above, the present invention controls the engine rotational energy release time according to the engine rotational speed, and adds the engine rotational energy to the engine output only within that time. Regardless of the situation, the effect is that a hydraulic output greater than the engine output can be obtained for a period of time corresponding to the rotational speed at that time, resulting in smooth operation.

[Brief explanation of drawings]

Fig. 1 is a constant force curve and pressure-flow characteristic diagram of a variable displacement hydraulic pump, Fig. 2 is a schematic explanatory diagram of a conventional variable displacement hydraulic pump, and Fig. 3 is the same (showing another conventional example). FIG. 4 is a schematic diagram showing an embodiment of the present invention in which the delay time is varied according to the engine speed. 1...Engine, 1a...Flywheel, 2...
・Variable displacement hydraulic pump, 3... cylinder, 4...
Piston, 5...Housing, °6...Sleeve,
7... Stool, 8... Rod, 9... Pressure receiving bottle, 10... Spring, 11, 14, 15... Pipeline, 12... Main circuit, 13... Hydraulic power source, 16...
・Time delay mechanism, 16a...Variable aperture, 16b・
...Accumulator, 16d...Spring, 16e
... cylinder, 17 ... strainer, 18 ... tank, 19 ... rotation speed detection device.

Claims (1)

[Claims] 1 A variable displacement cedar hydraulic pump driven by an engine, a regulator that detects the discharge pressure of the variable displacement cedar hydraulic pump and controls the flow rate so that the pump hydraulic output does not exceed the engine output, and a regulator based on the discharge pressure. In the regulator circuit of a variable capacity cedar hydraulic pump, which is equipped with a time delay mechanism that delays the operation of the engine, the engine rotation speed detection device and the delay caused by the time delay mechanism according to the increase or decrease in the engine rotation speed detected by the rotation speed detection device. A regulator circuit for a variable capacity cedar hydraulic pump characterized by having a control mechanism for increasing/decreasing time.