JPH02163502A - Actuator drive hydraulic circuit - Google Patents

Abstract

PURPOSE:To keep oil under low viscosity condition so as to increase responsiveness by providing a hydraulic actuator operated according to hydraulic pressure in an operation chamber and flow control means capable of adjusting oil quantity passing through a restriction provided at a discharge oil passage. CONSTITUTION:A multiple disc clutch 15 restricts differential motion by moving a piston 25 outwards according to hydraulic pressure in an operation chamber 27 to make an inner plate 19 contact with an outer plate 20 frictionally so as to connect a drum case 18 with an output shaft 14. Pressurized oil discharged from an pump 31 is returned to a reservoir tank 33 via a supply pipe 32, an inlet port 29, the operation chamber 27, an outlet port 30 and a discharged pipe 35 and is circulated like this. The back pressure of a restriction 34 is varied to drive hydraulic actuators 28R, 28L. Thus, the oil in a circuit can be kept under a high temperature and low viscosity condition to obtain high responsiveness.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a hydraulic circuit for driving an actuator.

(Prior Art) A hydraulic actuator guides pressure oil discharged by a pump or the like into an operating chamber, and operates according to the oil pressure within the operating chamber. Conventionally, such a hydraulic actuator connects a port opening into the working chamber to a drive hydraulic circuit, and this hydraulic circuit connects the port to both the pump and the reservoir tank in parallel via a control valve such as a directional control valve. do. The operation of the hydraulic actuator is controlled by selectively communicating the working chamber with the pump or the reservoir tank through the port by switching the directional switching valve of the hydraulic circuit.

(Problem to be Solved by the Invention) However, in the conventional dual hydraulic circuit for driving hydraulic actuators, the oil between the directional control valve and the working chamber (non-circulating part) is used to operate the directional control valve. Since the oil in the non-circulating portion only flows at certain times, the temperature of the oil in the non-circulating portion is difficult to rise in low-temperature environments and has a high viscosity, which causes a problem in reducing the responsiveness of the hydraulic actuator.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an actuator drive hydraulic circuit that can provide a hydraulic actuator with high responsiveness even in a low-temperature environment.

(Means for Solving the Problems) The actuator drive hydraulic circuit of the first invention is shown in FIG.
As shown in a), a hydraulic actuator in which an inlet port and an outlet port open into a working chamber independently and separated from each other, and are operated according to the hydraulic pressure in the working chamber;
A pump that pressurizes oil in a reservoir tank and discharges it from a discharge port, a supply oil path that connects the discharge port of the pump and the inlet port of the hydraulic actuator, and an OUT 1 knot port of the hydraulic actuator and the reservoir tank. The gist of the present invention is to have a discharge oil passage communicating with the discharge oil passage, a throttle interposed in the discharge oil passage, and a flow rate control means capable of adjusting the amount of oil passing through the throttle, and also, a second invention. As shown in FIG. 1(b), the actuator drive circuit includes a hydraulic actuator whose inlet port and outlet open into a working chamber independently and separated from each other, and which operates according to the hydraulic pressure in the working chamber, and a reservoir. A pump that pressurizes oil in a tank and discharges it from a discharge port, a supply oil path that connects the discharge port of the pump and an inlet port of the hydraulic actuator, and an outlet port of the hydraulic actuator and the reservoir tank. The gist is to have a discharge oil passage, a variable throttle interposed in the discharge oil passage, and an opening adjustment means capable of adjusting the opening of the variable throttle.

(Operation) According to the actuator drive hydraulic circuit according to the first invention, the pump is constantly driven to discharge pressure oil, and this pressure oil flows through the supply oil path, inlet port, working chamber, outlet port, and discharge oil path. The flow returns to the reservoir tank and circulates through the circuit, and the back pressure of the throttle is introduced into the operating chamber.Therefore, by adjusting the flow rate passing through the throttle using the flow rate control means, the operation of the hydraulic actuator can be controlled. Also,
By circulating the oil in the circuit, it is possible to maintain a relatively high temperature and low viscosity state even in a low temperature environment, resulting in low oil flow resistance and high responsiveness.

Further, according to the actuator drive hydraulic circuit according to the second invention, the operation of the hydraulic actuator can be controlled by adjusting the opening degree (flow path area) of the variable throttle using the opening adjustment means, and this is similar to the first invention. Since oil circulates throughout the system, oil flow resistance is reduced and high responsiveness is achieved.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing an actuator drive hydraulic circuit according to an embodiment of the first invention. This embodiment is applied to a differential of a vehicle that uses a hydraulic multi-disc clutch to control differential, and the hydraulic multi-disc clutch is driven by a hydraulic actuator.

In the figure, reference numeral 11 indicates a rear wheel differential, and the differential 11 has a housing 12 supported by a vehicle body (not shown). The housing 12 has an input shaft 13 at the front and hollow output shafts 1.4L, 14. R is rotatably supported, and multi-disc clutches 15L and 15R are housed therein. The input shaft 13 has a front end connected to a transmission via a propeller shaft or the like, and a drive gear 13 fixedly attached to a rear end. The output shafts 14L and 14R have joints 16L and 16R at their outer ends, respectively, and shafts 17L and 1.7
R is fitted and connected to the left and right rear wheels via a joint 16L16R and an axle (not shown).

The thermal multi-disc clutches 1.5L, 1.5R are provided with the aforementioned output shafts 14L, 14. R passes through the left and right sides so as to be rotatable and axially movable, and each output shaft 1
A plurality of inch plates 19L and 19R are provided on the outer periphery of the inner end of 4L and 1.4R, and a drum case 18
A plurality of outer plates 20L and 20R are divided into left and right groups on the inner periphery of the actuator brake 1-20L, which are connected by splines or the like so that they can rotate together and move in the axial direction. Inner plate 1 of shaft 14L
9L is also a group of outer plates 20 on the right side in the figure.
R and the inner brakes 1-19R of the output shaft 14R are alternately arranged so as to be able to make frictional contact with each other. Brakes 1-19L, 20L, 19R, and 2OR are pressed by a hydraulic actuator to be described later and come into frictional contact with these multi-disc clutches 15L1.5R, and transmit torque corresponding to the pressing force. The drum case 18 has needle bearings 21L and 21R on the inner wall of the housing 12 on both left and right sides, respectively.
The input shaft 1 is rotatably supported on the outer periphery.
Driven gear 18a that meshes with drive gear 13a of No. 3
is permanently installed.

The output shafts 1.4L and 14R each have a hollow cylindrical shape, and a collar 22 is rotatably fitted to the opposing inner end portions, so that the output shafts 1.4L and 14R are coupled to each other so as to be relatively rotatable.

Further, flanges 23L and 23R are fitted to the outer peripheries of the output shafts 14L and 14R, respectively, outside the housing 12. These flanges 23L, 23R are biased inwardly, that is, in a direction toward each other, by a spring (not shown), and a ball bearing 24. Substantially annular pistons 25L and 25R are rotatably provided via L and 24R. These pistons 25L, 25R are connected to annular grooves 26L, 26 formed on the side of the housing 12 described above.
Slideably fit into the hydraulic actuators 28L and 2.
It constitutes 8R. These hydraulic actuators 28L
, 28R are the pistons 25L in the annular grooves 26L, 26R.
, 25R define working chambers 27L, 27R, and the output shaft 1.4 L is adjusted according to the oil pressure in the working chambers 27L, 27R.
l, 4. Drive R in the axial direction. In addition, each multi-plate clutch 15L, 15R and hydraulic actuator 28L,
Since the configuration of 28R is the same, some illustrations are omitted,
In addition, the following description will be made using representative numbers without subscripts. The working chambers 27 of these hydraulic actuators 28 each have an inlet port 29 and an outlet port 30 formed in the housing 12 for approximately 180 degrees in the circumferential direction.
The inlet ports 1 and 29 are connected to the discharge port of a variable displacement oil pump 31 via a supply pipe 32, and the outlet port 30 is connected to a reservoir tank 33 via a discharge pipe 35 provided with a throttle 34. have been contacted.

The oil pump 31 is connected to a control device (not shown),
Pressurized oil is discharged at a discharge amount according to the drive signal output by the control device.

In the case of such a differential device, the piston 25 of the multi-plate clutch 15 moves outward according to the hydraulic pressure in the working chamber 27, and the inner plate 19 and the outer plate 20 come into frictional contact with each other. Frictional contact between the inner plate 19 and the outer plate 20 connects the drum case 18 and the output shaft 14 to limit differential movement. This differential device constantly drives the oil pump 31 at a predetermined discharge amount, and the pressure oil discharged by the pump 31 is transferred to the supply pipe 32, inlet port 29, working chamber 27, outlet port 30, and discharge pipe 35. The water is returned to the reservoir tank 33 for circulation. At this time, the working chamber 27 has a throttle 3 as shown in the formula below.
4, a back pressure P proportional to the square of the oil flow rate Q is applied, and the multi-disc clutch 15 is connected between the tram case 18 and the output shaft 14, that is, the human power shaft 13, with a fastening force according to the oil pressure P in the working chamber 27. and the output shaft 14.

PαQ2/A Therefore, the differential between the left and right rear wheels is limited in the region where the driving force, that is, the transmitted torque is smaller than the engagement force of the multi-disc clutch 15; Differentials are allowed in areas exceeding .

On the other hand, this differential device adjusts the discharge amount of the pump 31 according to vehicle conditions such as turning, and performs differential limiting control. That is, as is clear from the above equation, when the discharge amount Q of the pump 31 increases or decreases, the back pressure P of the throttle 34 also increases or decreases, so the multi-disc clutch 15 is engaged according to the back pressure P, that is, the oil pressure P in the working chamber 27. The force increases or decreases and differential limiting control is performed. Here, as described above, the pump 31 always discharges pressure oil, the pressure oil always flows in the entire circuit, and the pressure oil in the circuit is maintained at a relatively high temperature even in a low temperature environment.

For this reason, the pressure oil in the circuit has low viscosity and low flow resistance.
The multi-disc clutch 15 operates quickly and provides high control responsiveness.

In the above-described embodiment, a variable displacement pump 31 is used, but it goes without saying that the present invention can also be achieved using a flow rate control valve.

Further, the second invention is achieved by replacing the aperture 34 in the above-described embodiment with a variable aperture whose flow path area is variable. In this embodiment, as understood from the above equation, the multi-disc clutch 1 can be adjusted by adjusting the flow path area of the variable throttle.
5, the oil pressure in the working chamber 27 changes, and the tightening force also changes.

Note that since this aspect can be clearly understood from the above-mentioned FIG. 1(b) and the above-described embodiment, illustration and explanation will be omitted.

Further, in the embodiments described above, the multi-disc clutch of the differential gear is shown as a hydraulic actuator, but the present invention can also be applied to hydraulic cylinders of machine tools, etc.

(Effects of the Invention) As explained above, according to the present invention, the pressure oil discharged by the pump is constantly supplied to the working chamber of the hydraulic actuator from the inlet port 1, and the oil in the working chamber of the hydraulic actuator is supplied from the outlet port. The oil in the circuit can be maintained at a relatively high temperature and low viscosity state by circulating the flow through a throttle and changing the back pressure of the throttle to drive the hydraulic actuator, resulting in high responsiveness.

[Brief explanation of the drawing]

FIG. 1(a) is a circuit configuration diagram of an actuator drive hydraulic circuit according to the first invention, FIG. 1(b) is a circuit configuration diagram of an actuator drive hydraulic circuit according to the second invention, and FIG. 2 is an embodiment. FIG. 2 is a cross-sectional circuit diagram showing a mechanical part of the actuator drive hydraulic circuit of FIG. 11... Actuation device 15L, 15R... Multi-plate clutch 2SL, 28R... Hydraulic actuator 29... Inlet port 30... Outlet port 31... Oil pump 32... Supply pipe 33...
・Reservoir tank 34... Throttle 35... Discharge pipe

Claims (2)

[Claims] (1) An inlet port and an outlet port open into a working chamber independently and separated from each other, and a hydraulic actuator operates according to the hydraulic pressure in the working chamber, and a hydraulic actuator pressurizes oil in a reservoir tank and discharges it from a discharge port. a pump; a supply oil passage that communicates between a discharge port of the pump and an inlet port of the hydraulic actuator; a discharge oil passage that communicates an outlet port of the hydraulic actuator with the reservoir tank; and a discharge oil passage that is interposed in the discharge oil passage. An actuator drive hydraulic circuit characterized by comprising: a throttle having a diameter of 100 mm, and a flow rate control means capable of adjusting the amount of oil passing through the throttle. (2) A hydraulic actuator whose inlet port and outlet open into a working chamber independently and separated from each other, and which operates according to the hydraulic pressure in the working chamber; and a pump which pressurizes oil in a reservoir tank and discharges it from a discharge port. a supply oil passage that connects the discharge port of the pump and the inlet port of the hydraulic actuator; a discharge oil passage that connects the outlet port of the hydraulic actuator and the reservoir tank; and a discharge oil passage that is interposed in the discharge oil passage. An actuator drive hydraulic circuit comprising: a variable throttle; and an opening adjustment means capable of adjusting the opening of the variable throttle.