JPH0421048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention provides a method for controlling a device to be controlled when the rotational speed of a prime mover such as an engine or a motor becomes lower or higher than a predetermined value. The present invention relates to an actuator drive pressure control device for a hydraulic system used to switch and control operating states using a hydraulic actuator.

<Prior art> This type of device basically supplies hydraulic oil from the hydraulic pump 2 by driving the hydraulic pump 2 with a variable rotational speed prime mover 1, as shown in FIG. 1 or FIG. The hydraulic oil is supplied to the hydraulic actuator 5 through the pressure oil path 4, and the hydraulic actuator 5 is driven by the hydraulic pressure of this hydraulic oil, so that the hydraulic actuator 5 is controlled and driven in accordance with the rotational speed of the prime mover 1.

Conventionally, as a structure for switching and operating the hydraulic actuator 5 at a predetermined rotation speed,
In the above basic structure, the hydraulic actuator 5 is simply communicated with the hydraulic pump 2 through the pressure oil passage 4, so that the hydraulic actuator 5 is controlled and driven by the working oil pressure. That is, as shown in FIG.
The discharge pressure of the hydraulic pump 2 corresponds to the rotational speed N of
P ₀ changes, but the hydraulic oil pressure P ₅ that continuously changes in proportion to this discharge pressure Po is transmitted to the hydraulic actuator 5 as it is, and the hydraulic actuator ₅ is driven by this hydraulic oil pressure P 5. It was composed.

<Problems to be Solved by the Invention> In the conventional structure described above, when switching the hydraulic actuator 5 at a predetermined rotational speed, the hydraulic actuator 5 cannot be switched instantly;
There was a problem with low operating accuracy.

That is, to explain the case where, for example, a spring return type hydraulic cylinder is used as the hydraulic actuator 5, the tension of the return spring 5a changes in a constant width as the hydraulic cylinder 5 changes to expand or contract, and this tension change range causes the hydraulic cylinder to The driving pressure range _P6 required for the expansion/contraction switching is determined. Further, in order to ensure the stability of the operation of the hydraulic cylinder 5, it is necessary to set the tension of the return spring 5a to be strong, and accordingly, the tension change range and the switching drive pressure range _P6 become relatively wide.

In the above conventional structure, since the working oil pressure P ₅ that drives the hydraulic cylinder 5 changes continuously and gently with respect to the rotational speed N of the prime mover, the switching driving pressure region
The switching rotational speed range No. for P ₆ becomes wider.

Within the switching rotational speed range No., hydraulic cylinder 5
Since the operation of the hydraulic cylinder 5 becomes unstable, the wider the switching rotational speed range No., the more likely the operation of the hydraulic cylinder 5 will become unstable.

Furthermore, if the switching rotational speed range No. is wide, the hydraulic cylinder 5 cannot be switched instantly.

In addition, hydraulic equipment has accumulation errors due to manufacturing errors in each part, and this accumulation error causes switching drive pressure range P ₆
As the rotational speed shifts, the switching rotational speed region No. is largely biased toward the high rotational side or the low rotational side.

The present invention solves the above problems, shortens the switching rotational speed range that causes poor hydraulic actuator control, and
The purpose is to reduce deviation in the switching rotational speed region.

<Means for Solving the Problems> The present invention provides, for example, as shown in FIG. Connect these relief valves 6,
7 are set to different values, and the on-off switching valve 3 is interposed in the communication path 4a between the low-pressure relief valve 7, which has a small relief pressure setting value, and the pressure oil line 4, and the on-off switching valve 3 is used for opening. The spring 3a opens the opening/closing switching valve 3, and a hydraulic pressure on the upstream side of the connection position of the relief valves 6 and 7 is applied to the switching valve 3, and this hydraulic pressure on the upstream side increases as the rotational speed of the prime mover 1 increases. This feature is characterized in that when the pressure exceeds the set pressure, the opening/closing switching valve 3 is closed by overcoming the valve opening spring 3a.

<Effect> The invention works as follows.

The hydraulic pump 2 is driven by the prime mover 1 to supply hydraulic oil to the hydraulic actuator 5 through the pressure oil path 4, and also to the relief valves 6, 7 and the on-off switching valve 3 along the way.

At this time, with respect to the rotational speed N of the prime mover 1, the discharge pressure P ₀ of the hydraulic pump 2 and the operating pressure P _W of the on-off switching valve 3
The hydraulic pressure of the hydraulic oil supplied to the hydraulic actuator 5 to drive the actuator (that is, the actuator drive pressure) P _C is as shown in FIG. 4. Among these, the pump discharge pressure P ₀ is determined by the rotational speed N, and the switching valve operating pressure P _W is the value obtained by lowering the pump discharge pressure P ₀ due to the passage resistance of the pressure oil passage 4, and the actuator drive pressure P _C becomes the relief pressure of reliefs 6 and 7.

In the low speed region N _L where the rotational speed N of the prime mover 1 is lower than the predetermined rotational speed _N1 , the switching valve operating pressure _PW is lower than the valve opening setting pressure _P1 set by the valve opening spring 3a, so the switching valve is closed. 3 is in an open state, and the low pressure relief valve 7 is communicated with the pressure oil passage 4. This causes the actuator drive pressure P _C to decrease to the low pressure relief valve 7.
The relief pressure P ₃ is maintained lower than the switching drive pressure region P ₆ of the actuator 5, and the actuator 5 is in the returned position by the return spring 5a and is held in an inoperable state.

When the rotation speed 2 passes through the predetermined rotation speed N ₁ on the way from the low speed region N _L to the high speed region N _H , the switching valve operating pressure increases as the pump discharge pressure P ₀ increases.
P _W rises and reaches the valve opening set pressure P ₁ and the on-off switching valve 3 begins to close. Then, since the valve opening area is narrowed, the amount of hydraulic oil escaping from the low pressure relief valve 7 is suppressed, the valve operating pressure _PW increases rapidly, and the on-off switching valve 3 is instantly closed. Due to this closing operation of the on-off switching valve 3, the low pressure relief valve 7 no longer acts, and the actuator drive pressure P _C rises rapidly and instantly passes through the switching drive pressure region P ₆ , and the high pressure relief valve 6 acts, the relief pressure of the high pressure relief valve 6 is switched to _P4 , and the actuator 5 operates against the return spring 5a to extend the output rod 5b.

When moving from the high speed region _NH to the low speed region _NL , the operation is reversed to the above and the output rod 5b of the actuator 5 is switched to the contracted state.

<Examples> Examples according to the present invention will be described below based on the drawings.

FIG. 3 is a perspective view schematically showing a three-cylinder engine. In FIG. 3, reference numeral 2 denotes a booster pump which is interlocked and connected to the crankshaft 10 of the engine 1 and pumps hydraulic oil to required parts, and 11 denotes a booster pump 2.
12 is a piston connected to the main pressure oil passage 11 and drives the control shaft 13; 4 is a pressure oil passage branched from the main pressure oil passage 11; 5 is a pressure oil passage connected to the pressure oil passage 4; connected, 2
A hydraulic actuator 8 is provided in the pressure oil passage 4 to switch and drive the clutch 15 for swirl switching the valve intake head 14, and outputs actuator drive pressure P _C in a stepped manner to control and drive the hydraulic actuator 5. This is a pressure control means.

FIG. 1 shows a first embodiment of an actuator drive pressure control device according to the present invention, and FIG. 2 is a cross-sectional view of the pressure control means 8 in FIG.

In these figures, the pressure control means 8 includes a high pressure relief valve 6 provided in the pressure oil passage 4 and a low pressure relief valve connected to the pressure oil passage 4 on the downstream side of the high pressure relief valve 6 via a communication passage 4a. It is composed of a valve 7 and an on-off switching valve 3 that opens and closes the communication path 4a.

The on-off switching valve 3 pushes open the valve body 3b with a valve opening spring 3a so that the valve body 3b opens the communication passage 4a,
The valve-opening force of the valve-opening spring 3a can be adjusted with an adjustment tool 3c, and the pressure-receiving surface 3d of the valve body 3b is positioned in the oil passage upstream of the high-pressure relief valve 6 connection position of the pressure oil passage 4. and the rotational speed N of engine 1
Corresponding to the rise of the valve, the hydraulic pressure P _W at this position presses the valve body 3b, overcomes the opening force of the valve opening spring 3a, and closes the communication passage 4a.

In FIG. 2, the high pressure relief valve 6 has a valve body 6b.
By compressing the valve body 6b with the compression spring 6a so as to narrow the pressure oil passage 4, and adjusting the elastic force of the compression spring 6a to a required setting pressure (for example, 5 kg/cm ² ) with the adjusting tool 6c. , hydraulic oil is relieved to the relief path 6e according to the set pressure. Due to this relief action, the working pressure downstream of the position where the high-pressure relief valve 6 is connected is reduced to the high-pressure actuator drive pressure required to control the hydraulic actuator 5.
It is configured to be P ₄ .

Furthermore, the low pressure relief valve 7 is configured in the same manner, and when the low pressure relief valve 7 acts, the working oil pressure of the pressure oil passage 4 downstream from the position where this low pressure relief valve 7 is connected is changed to the required low pressure actuator driving pressure P. ₃
(For example, 2.5Kg/cm ² ).

Therefore, as shown in FIG. 4, the engine rotation speed N
A stepped actuator drive pressure P _C can be obtained correspondingly, and the hydraulic actuator 5 can be controlled and driven using this actuator drive pressure P _C .

FIG. 5 is a schematic diagram showing a second embodiment of the actuator drive pressure control device according to the present invention, and in this figure, the same reference numerals as in FIG. 1 indicate the same members.

A high pressure relief valve 6 is connected to the pressure oil passage 4 from the upstream side.
and a plurality of low pressure relief valves 7a, 7b, 7c are connected to each other via communication passages 4a, 4b, 4c in order of decreasing set pressure of the relief pressure, and these communication passages 4a, 4b, 4c are connected to on-off switching valve 3
A is provided, and this on/off switching valve 3A opens the communication passage 4a of the low pressure relief valve 7a with the lowest set pressure by the valve opening spring 3a, and opens the pressure oil passage in accordance with the increase in the rotational speed N of the engine 1. The working hydraulic pressure P _W on the upstream side of the high pressure relief valve 6 of No. 4 overcomes the opening force of the valve opening spring 3a and pushes the communication passage 4a to close, and in the same way, the relief valves 7b, 7c, and
6 to open the hydraulic pressure as shown in Fig. 6.
It is configured such that a stepped actuator drive pressure P _C can be obtained with P _W . In this case,
The switching position of one hydraulic actuator can be controlled in multiple stages in response to the pressures of multiple low-pressure relief valves, and the switching position of multiple hydraulic actuators can be controlled in multiple stages in response to different rotational speeds of the engine 1. This is convenient for multi-stage control because it can be controlled sequentially.

<Effects of the Invention> As described in the <Operation> section, the present invention automatically operates the on-off switching valve when the prime mover passes through a predetermined rotational speed by changing the hydraulic pressure corresponding to the rotational speed of the prime mover. It can be switched automatically.

Due to the automatic switching operation of this on-off switching valve, the relief pressure of the pressure oil path is rapidly switched, so that the pressure of the hydraulic fluid supplied to the hydraulic actuator, that is, the actuator drive pressure P _C exceeds the switching drive pressure region P ₆ . It can be passed instantly.

Furthermore, since the switching rotational speed range with respect to the switching drive pressure range is very narrow, the operation of the actuator that is driven in accordance with the rotational speed of the prime mover is
This eliminates the possibility of an unstable state and allows the hydraulic actuator to be switched instantaneously by changing the working oil pressure. This is advantageous, for example, if the clutch is to be switched by means of this hydraulic actuator.

In addition, it is possible to almost eliminate control drive failures of the actuator that is driven in accordance with the rotational speed of the prime mover, and even if the switching drive pressure region deviates due to integration errors in the hydraulic system, this region can be used to control the low pressure relief valve. The switching speed range can be set between the low actuator drive pressure P ₃ set by the high-pressure relief valve and the high actuator drive pressure P ₄ set by the high-pressure relief valve. The hydraulic actuator can be accurately switched and operated at a predetermined prime mover rotation speed without deviation.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention, FIG. 2 is a sectional view taken along the arrow - in FIG. 1, and FIG. 3 is a conceptual diagram of a three-cylinder diesel engine to which the present invention is applied. FIG. 4 is a graph showing the relationship between engine rotational speed and working oil pressure/control oil pressure according to the first embodiment, FIG. 5 is a schematic diagram showing the second embodiment of the present invention, and FIG. 6 is a graph showing the second embodiment. A graph showing the relationship between engine rotation speed and working oil pressure/control oil pressure,
FIG. 7 is a hydraulic circuit diagram showing the prior art, and FIG. 8 is a graph showing the relationship between engine rotational speed and operating oil pressure/control oil pressure according to the prior art. 1...Variable rotational speed prime mover (engine), 2...
Hydraulic pump, 3... Open/close switching valve, 3A... Multiple on/off switching valve, 3a... Valve opening spring, 4... Pressure oil path, 4
a, 4b, 4c...Communication path, 5...Hydraulic actuator, 6...High pressure relief valve, 7, 7a, 7b, 7c
...Low pressure relief valve.

Claims (1)

[Claims] 1. By driving the hydraulic pump 2 with the variable rotational speed prime mover 1, hydraulic oil is supplied from the hydraulic pump 2 to the hydraulic actuator 5 through the pressure oil path 4, and the hydraulic pressure of this hydraulic oil is used to drive the hydraulic actuator. In the actuator drive control device for a hydraulic system configured to control and drive the hydraulic actuator 5 in accordance with the rotational speed of the prime mover 1 by driving the hydraulic actuator 5, the pressure oil passage 4 is provided with a high pressure relief valve 6 and a low pressure relief valve. 7, and these relief valves 6, 7
The on-off switching valve 3 is interposed in the communication path 4a between the low-pressure relief valve 7, which has a small relief pressure set value, and the pressure oil passage 4, and the on-off switching valve 3 has a valve opening spring. 3a, and both relief valves 6,
A working hydraulic pressure upstream of the connection position 7 is applied, and this upstream working hydraulic pressure exceeds the set pressure as the rotational speed of the prime mover 1 increases, thereby overcoming the valve opening spring 3a. 1. An actuator drive pressure control device for a hydraulic system, characterized in that the on-off switching valve 3 is closed when the actuator is closed. 2 Multiple low pressure relief valves 7 with sequentially different set pressures
a, 7b, 7c are connected to a plurality of communication paths 4a, 4, respectively.
b, 4c to the pressure oil passage 4, and these communication passages 4a, 4b, 4c are connected to the multiple on-off switching valve 3A.
An actuator drive pressure control device for a hydraulic system according to claim 1, wherein the actuator drive pressure control device is configured to sequentially switch to open and close the actuator.