JPS6162626A - Hydraulic control valve - Google Patents

Abstract

PURPOSE:To vary output operating oil amount by opening an input port and an output port respectively on an oil chamber formed by a first and a second pistons provided on a spool, and relieving the operation oil in the oil chamber by displacement of the spool. CONSTITUTION:A spool 3 provided with a first piston 1 and a second piston 2 is put in a valve body 4,and an electric actuator 5 is connected to the right end of the spool 3. The pistons 1, 2 of the spool 3 form an oil chamber 6, and on this oil chamber 6, an input port 9 connected to a hydraulic source 8 via a throttle 7 and an output port 12 connected to an electromagnetic switch valve 10 and a pressure switch 11 are opened. And an oil chamber 13 connected to a drain tank is formed on the left direction of the first piston and an oil chamber whose diameter is larger than that of the oil chamber 6 and connected to the drain tank is formed on the right direction of the second piston.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a hydraulic control valve IS suitable for use in hydraulic control of a speed change clutch that changes speed of a transmission using planetary gears.

[Conventional technology]

As is well known, a transmission using a planetary gear is configured to change gears by selectively operating a shift clutch provided corresponding to each gear of the planetary gear.

In such a transmission device, when hydraulic oil from the shift clutch VC overlapped hydraulic pump is applied, the oil pressure in the cylinder of the clutch rapidly rises, resulting in a so-called shift shock. Conventionally, therefore, a so-called modulating valve that acts to gradually reduce the oil pressure in the cylinder of the clutch has been used to alleviate the shift shock.

[Problem that the invention seeks to solve]

However, the above-mentioned conventional modulating valve can only provide uniform hydraulic control characteristics determined by the constant of the built-in spring, and as a result, when changing gears, the vehicle may suddenly accelerate or decelerate due to load fluctuations. In this case, it was not possible to sufficiently suppress the shift shock.

[Means for solving problems]

The hydraulic control valve according to the present invention has a first hydraulic control valve provided on a spool.
By opening an input port and an output port in an oil chamber defined by a second piston, and displacing the spool with an electric actuator, the hydraulic oil in the oil chamber is caused to flow, resulting in the output. The amount of hydraulic oil output from the port is varied.

[Effect]

According to the present invention, the pressure oil in the oil chamber is drained as the spool is displaced, thereby changing the amount of hydraulic oil output from the output port.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of a hydraulic control valve according to the present invention applied to hydraulic control of a speed change clutch of a planetary gear type power shift transmission mounted on a construction vehicle.

As shown in the figure, in the hydraulic control valve according to this embodiment, a spool 3 having a first piston 1 and a second piston 2 is arranged in a valve body 4, and an electric actuator 5 is mounted on the right end of the spool. are connected.

Each piston 1, 2 of the spool 3 defines an oil chamber 6, and this oil chamber 6 has an input port 9 connected to a hydraulic pressure source 8 via a throttle 7, an electromagnetic switching valve 10, and a pressure The output ports 12 connected to the switch 11 are each opened. An oil chamber 13 connected to the drain tank is formed on the left side of the first piston, and an oil chamber 13 connected to the drain tank and having a larger diameter than the oil chamber 6 is formed on the right side of the second piston. An oil chamber 14 is formed.

A stopper 15 is formed on the inner peripheral surface of the valve body 4 located within the oil chamber 6 to prevent the second piston 2 from blocking the port 9.12. Further, below the oil chamber 13, there is an I for adjusting the output pressure of the hydraulic power source 8.
A J IJ-7 valve 16 is formed.

Clutch cylinders 17A and 17B operate clutches for changing speeds for different speed stages in a power shift transmission using planetary gears (not shown), and are selected by hydraulic oil supplied via electromagnetic valve 10. activated.

The electric actuator 5 has a mechanism for linearly moving a rod 18 connected to the spool 3 by a servo motor (not shown), and is driven via a servo amplifier based on a control signal output from a controller 19. Note that this actuator 5 is equipped with a position detector such as a button 2 thometer that detects the operating position of the rod 18, that is, the position of the spool 3, and the output of the detector is applied to the controller 19 as a position feedback signal. .

The pressure control valve according to this embodiment operates as follows.

Now, assuming that hydraulic oil is supplied to the clutch cylinder 17B and the speed change clutch for this cylinder is in an engaged state, the oil pressure at the 1st output port 12 is equal to the value P1 when the clutch is engaged, as shown in FIG. It shows.

When the solenoid valve 10 is switched by the output of the controller 19 to operate the clutch cylinder, the hydraulic oil in the cylinder 17B is drained through the valve 10, so the clutch for the cylinder 17B is It becomes a disengaged state. On the other hand, when the electromagnetic valve 10 is switched, the oil pressure at the output port 12 suddenly drops to a value P, as shown in FIG. This is cylinder 17
This is because hydraulic oil is supplied to the space existing in A and the pipe line connected to the cylinder. When the time (filling time) for filling the space and pipe with hydraulic oil has elapsed, the oil pressure at the output port 12 begins to rise as shown in FIG. It is arranged that the coefficient d<°engages≦l.

Now, assuming that the spool 3 is in the position shown in FIG. 1, the oil pressure at the output port 12, that is, the oil pressure in the clutch cylinder 17A, is approximately proportional to time as shown by the dotted line (A) in FIG. and eventually the value P
1 and press the clutch.

On the other hand, after the above feeling time, the '7EJ
) When the actuator 5 is actuated to move the spool to the right, the oil chamber 6 is communicated with the oil chamber 14 as shown in FIG. is drained through. Part of the hydraulic oil in the oil chamber 6 flowing into the oil chamber 14 suggests a decrease in the oil pressure in the output port 12, that is, the oil pressure in the clutch cylinder 17A,
Therefore, by operating the electric actuator 5, the hydraulic pressure increase characteristic of the clutch cylinder 17A can be changed. That is, for example, it is possible to obtain the curved oil pressure increase characteristic shown in FIG.

Note that the clutch engagement time for characteristic (ell(Dl) is significantly longer than that for characteristic (5).

Incidentally, the degree of shift shock changes depending on the gear position, vehicle weight alignment, throttle opening, etc.

The controller 19 outputs a control signal to the electric actuator 5 to reduce shift shock based on the output of the sensor that detects the state. For example, when the vehicle weight is large due to cargo, Even if the clutch engagement time is shortened, a shift shock does not occur, so the actuator 5 is controlled so that the oil pressure rises as shown in characteristic (8).On the other hand, if the vehicle weight is small, a shift shock is not generated. In order to prevent this, the actuator 5 is adjusted so that the hydraulic pressure rises as shown in the characteristic diagram.
control.

In this embodiment, the end point of the filling time is the pressure sensor 1 connected to the output port 12.
Judging from the output of 1.

In the above embodiment, a servo motor is used as the drive source for the electric actuator 5, but it is of course possible to use a plunger type solenoid or the like which can be proportionally controlled instead of this.

〔Effect of the invention〕

According to the present invention, the hydraulic oil pressure output from the output port can be arbitrarily controlled by an electric signal. Therefore, for example, by applying the present invention to the clutch pressure control of a power shift transmission as shown in the embodiment, it is possible to control the oil pressure so as not to generate a shift shock.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing an embodiment of the hydraulic control valve according to the present invention, Fig. 2 is a hydraulic pressure change characteristic diagram showing the action of the embodiment shown in Fig. 1, and Fig. 3 is a diagram showing the spool. It is a figure showing an example of a displaced state. 1.2... Piston, 3... Spool, 4... Valve body, 5... Electric actuator, 6, 13
, 14... Oil chamber, 7... Throttle, 8... Hydraulic source,
9...Input port, 10...TL magnetic valve, 11...
Pressure sensor, ]2... Output port, 17A, 17B.
...Clutch cylinder, 18...Rod, 19...
Controller, add...servo amplifier.

Claims (1)

[Claims] The spool includes a hydraulic pressure defined by first and second pistons provided on the spool, an electric actuator that displaces the spool, and an oil path that relieves hydraulic oil in the oil chamber as the spool is displaced. , a hydraulic control valve having an input port and an output port opened in the oil chamber.