JPH01261504A - Control valve structure - Google Patents

Abstract

PURPOSE:To make it possible to control, with a linear characteristic, an oil quantity by providing a valve body having a main pressure chamber and a back pressure chamber in an exhaust oil passage branched from the main oil passage and also providing a valve main body having a solenoid valve between a discharge oil passage having the main oil passage and a throttle and the back pressure chamber. CONSTITUTION:There is provided a valve body 18 having a main pressure chamber A and a back pressure chamber B in an exhaust oil passage 17 branched from a main oil passage 15. Between a discharge oil passage having the main oil passage 15, back pressure chamber B and a throttle 20, and a back pressure chamber B, there is provided a solenoid valve 23 for changing the intercommunication between the discharge oil passage and the back pressure chamber B. This enables the actuation of the solenoid valve 2 with a small capacity and a smooth actuation thereof with an intermitted signal of a high frequency. Besides, it is possible to control, with a linear characteristic, an oil quantity by adjustment of a duty cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control valve structure, and more particularly to a technique for slightly operating a hydraulic actuator such as a hydraulic cylinder by electrical control.

[Conventional technology]

To take an example of a system in which a hydraulic cylinder is electrically controlled, there is a conventional system in which a solenoid valve is interposed in a pressure oil supply system for a hydraulic cylinder (references not listed).

In addition, when attempting to slightly operate a hydraulic cylinder using the electric Tr 141 in this way, the solenoid valve is controlled by intermittent ON/OFF signals, and the ratio of ON/OFF, that is, Fine actuation of the hydraulic cylinder was possible by adjusting the duty cycle.

[Problem to be solved by the invention]

However, when trying to control a hydraulic cylinder with a solenoid valve, not only does the solenoid valve require a large capacity, which increases the manufacturing cost of the hydraulic system, but also the control signal to the solenoid valve requires a large current. control′
There are also disadvantages such as the inability to increase the capacity of the III signal system, so there is room for improvement.

Therefore, as shown in Fig. 4, it is conceivable to configure the structure with a small-capacity solenoid valve. In this configuration, the main oil path (15) from the hydraulic pump (11) to the hydraulic cylinder (5) is considered.
) is interposed with a check valve (16), and two oil drain passages (17) are formed at positions sandwiching the check valve (16), respectively.
A valve body (18) is provided which is urged by a spring (24) to close the valve body (17), and pressure from the oil drain passage (17) is applied in a direction to open the valve body (18). main pressure chamber (A) and an orifice (18) formed in the valve body (18).
A back pressure chamber (B) to which pressure oil from the main pressure chamber (A) is sent via a) is formed, and the oil from the back pressure chamber (B) is further guided to the drain oil path (19). The control valve includes a solenoid valve (30) which can be switched to a state in which oil from the back pressure chamber (B) is sealed off.

When supplying pressure oil to the hydraulic cylinder (5) with this control valve, the main pressure chamber (A) and back pressure are controlled by operating the respective solenoid valves (30) and (30) to the closed position. Room (B
) and the biasing force of the spring (24) acts, so the valve body (18) closes and pressurized oil is supplied. In addition, when slightly operating the hydraulic cylinder (5), the pressure in the back pressure chamber (B) is adjusted by driving the solenoid valve (30) on the supply side (lower side in the figure) with the intermittent signal (S). to obtain the desired control oil amount.

Incidentally, when draining oil from the hydraulic cylinder (5), this can be done by operating the solenoid valve (30) on the unloading side (upper side in the figure).

Moreover, according to the result of manufacturing and operating the control valve configured in this manner by the applicant, the pressure generated in the back pressure chamber (B) is caused by the orifice (18a) formed in the valve body (18). Hydraulic cylinder (5
Even if the solenoid valve (30) is driven with an intermittent signal for the purpose of slightly operating the As a result of draining oil from the pressure chamber (B), the valve body (18) operates in the opening direction more than necessary, and the control oil amount may be less than the desired value, so there is room for improvement. .

Although it is possible to obtain the required amount of control oil by lowering the frequency of the intermittent signal with this control valve, the amount of control oil relative to the amount of adjustment of the duty cycle of the intermittent signal is expressed non-linearly. There is room for improvement in this respect as well.

As mentioned above, the purpose of the present invention is to configure a control valve that operates with a small-capacity solenoid valve by providing a valve body in a drain oil passage branched from a main oil passage, and to provide a control valve that operates smoothly even with high-frequency intermittent signals. The object of the present invention is to obtain a structure of a control valve that can be operated in a linear manner and control the amount of oil with linear characteristics by adjusting the duty cycle.

[Means to solve the problem]

A feature of the present invention is that it includes a valve body that is biased in a direction to close an oil drain passage branched from the main oil passage, and that releases pressure from the main oil passage to the valve body to open the oil drainage passage. A main chamber is formed in which pressure is applied to the valve body to block the drain oil passage, and a back pressure chamber is formed in which pressure to block the oil drain passage is applied to the valve body. It comprises an electromagnetic valve that can be switched to a state in which oil is sent out, and a restrictor that suppresses the flow of oil sent out from the back pressure chamber, and its functions and effects are as follows.

[For production]

If the above characteristics are configured as shown in FIG. 1, for example, when the valve body (18) is operated in the closing direction, the pressure in the oil drain passage (17) is transferred to the back pressure chamber (B) via the solenoid valve (23). acts on,
Also, when operating the valve body (18) in the direction of opening, oil from the back pressure chamber (B) flows into the solenoid valve (23) and the throttle part (20
) to the drain oil passage (19).

In other words, in this structure, the pressure generated in the back pressure chamber (B) for the purpose of operating the valve body (1 day) in the direction of closing is sent from the hydraulic pump (11) side without passing through an orifice etc. Therefore, the movement of the valve body (18) in the direction of closing is quick, and the restriction part is used for draining oil from the back pressure chamber (B) for the purpose of moving the valve body (18) in the direction of opening. (20) acts, it is possible to suppress the steep movement of the valve body (18).

In addition, in a structure in which the valve body (18) is opened by pressure from the hydraulic pump (11), the opening operation is performed faster than the closing operation, so the opening and closing of the valve body (18) is By configuring the control system, opening and closing operation speeds are balanced and high-speed operation is also possible.

〔Effect of the invention〕

Therefore, by providing a valve body in the drain oil path branched from the main oil path, it is possible to operate with a small-capacity solenoid valve, operate smoothly with high frequency intermittent signals, and reduce the duty cycle. This resulted in a control valve structure that can control the oil amount with linear characteristics by adjusting the .

In particular, in the present invention, an experiment comparing the control valve shown in Fig. 4 revealed that the control valve shown in Fig. 4 causes slight vibrations to be disturbed by the human body during operation, whereas the control valve of the present invention has a high frequency setting. This also has the effect that slight vibrations are hardly disturbed during operation of the control valve.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 3 shows a side view of the rear part of an agricultural tractor equipped with the control valve according to the present invention. An output shaft (3) that drives the rear wheels (2) is protruded from both sides of the transmission case (1), and a pair of left and right lift arms (4), (4) are driven up and down on the upper part of the transmission case (1). A hydraulic cylinder (5) is housed therein, and a driver's seat (6) is arranged further above the hydraulic cylinder (5).

In addition, the lift arm (4) is located at the rear of the transmission case (1).
), (4) versus Riftrond (7), (7)
Lower links (8), (8) are provided which are connected via the lower links (8), (8) and the top link (9) provided on the rear surface of the transmission case (1). A device (R) is connected to the vehicle body.

As shown in the figure (a rolling cylinder (10) is interposed in the right lift iron (7), the rotary tillage bag W (R) is raised and lowered by the drive of the hydraulic cylinder (5), and , is configured to perform a rolling operation by driving this rolling cylinder (10).

The hydraulic system of this tractor is shown in FIG. 2, and the operation of the hydraulic cylinder (5) is controlled by a control valve (V) shown in the same figure.

In other words, inside this control valve (V), there is a pump boat (
A relief valve (
12), an unload valve (13) that opens when the amount of hydraulic oil becomes excessive, and this pump boat (
A flow priority valve (14) to which hydraulic oil is supplied from P), a main oil passage (15) that sends surplus flow from this flow priority valve (14), and this main oil passage (15)
The check valve (16) installed in the
6), which are branched from the main oil passage (16), and these oil drainage passages (17).
7) Valve bodies (18) and (18) provided respectively;
A drain oil passage (19) through which drained oil is sent from the valve bodies (18), (1B),
) A constriction part (20) provided correspondingly.

(20) and a control oil passage (21) that sends a control flow from the flow priority valve (14), and furthermore, the main oil passage (15) is connected to the hydraulic cylinder via the cylinder port 1-(C). (5), and the control oil passage (21) and drain oil passage (19) communicate with a rolling valve (22) attached to the outside of this control valve (V). ) from the rolling cylinder (1
An oil passage is formed so that the oil is sent to the drain oil passage (19
) is constructed so that oil can be drained through the drain port (D).

As shown in FIG. 1, the valve body (18) and the throttle part (20)
and a solenoid valve (23) which is driven and operated by an intermittent signal (S) to control this valve body (18), so that the hydraulic cylinder (5) can be controlled. ing.

That is, each valve body (18) is biased by a spring (24) so as to close the oil drain path (17), and this valve body (18)
) is provided with a main pressure chamber (8) on the side of the oil drain passage (17) for applying pressure from the main oil passage (15) to the valve body (18) in the direction of opening the oil drain passage (17). A back pressure chamber (B) is formed on the spring (24) side of the valve body (18) to apply pressure in the direction of closing the oil drain path (17).

As shown in the figure, each of the throttle parts (20) is composed of a poppet valve (20b) biased by a coil spring (20a), and the opening degree is changed according to the pressure of the main pressure chamber (A). is configured to do so.

Then, the solenoid valve (23) transmits the pressure from the main pressure chamber (A) to the back pressure chamber (B), and the pressure in the back pressure chamber (B) is transmitted to the drain oil through the constriction part (20). When slightly operating the hydraulic cylinder (5) in the upward direction, the solenoid valve (23) on the supply side (lower side in Fig. 1) Intermittent signal (
S), the pressure in the back pressure chamber (B) and the pressure in the main chamber (8) reach a substantially balanced state, and the valve body (1)
8) can supply pressure oil to the hydraulic cylinder while discharging a part of the pressure oil in the main oil passage (15), and when slightly operating the hydraulic cylinder (5) in the downward direction, unloading is possible. By driving the side solenoid valve (23) (upper side in Fig. 1) with the intermittent signal (S), the pressure in the back pressure chamber (B) and the pressure in the main pressure chamber (A) are approximately equal to each other as described above. When a balanced state is reached, the valve body (18) can send pressure oil to the drain oil path (19) while suppressing the pressure oil in the main oil path (15).

In addition, the intermittent signal for the solenoid valve (23) is in the ON state and in the OFF state.
The control valve (v) is configured to be able to adjust the ratio between the F state and the so-called duty cycle, and in this control valve (v), as the ratio of the ON state of the intermittent signal to the solenoid valve (23) increases, the valve body ( 18) is displaced in the opening direction.

Moreover, the poppet valve (20b) of the throttle part (20) is connected to the main pressure chamber (
As the pressure in A) decreases, the opening of the throttle part (20) is expanded, so even when the pressure in the main pressure chamber (A) is low, the pressure in the back pressure chamber (B) can be quickly reduced. This makes it possible to lower the frequency of the intermittent signal, and exhibits smooth control characteristics even in a wide range from a state in which the frequency of the intermittent signal is set low to a state in which it is set high.

Incidentally, this control valve (V) ensures the amount of oil in the hydraulic pump (11) so that the hydraulic cylinder (5) can be controlled even when the tractor engine is idling, and also increases the engine rotational speed. In this case, the unload valve (13) discharges excess hydraulic fluid.

[Another example]

In addition to the above-described embodiments, the present invention can be implemented in various ways, such as by being equipped with a vehicle or device other than a tractor, and by configuring the throttle part with a fixed orifice, or by incorporating it into a solenoid valve. The shape and structure of the valve body can also be implemented in various ways.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the control valve structure according to the present invention, FIG. 1 is a sectional view showing the main parts of the valve structure, FIG. 2 is a hydraulic circuit diagram of the valve structure, and FIG. 3 is a rear view of an agricultural tractor. FIG. 4 is a sectional view showing a comparative example of the valve structure. (15)... Main oil passage, (17)... Oil drain passage, (18)... Valve body, (20)...
・Aperture part, (23)...Solenoid valve, (A)...
...Main pressure chamber, (B)... Back B, chamber.

Claims (1)

[Claims] The valve body (18) is provided with a valve body (18) that is biased in the direction of closing the drain oil passage (17) branched from the main oil passage (15), and the pressure from the main oil passage (15) is transferred to the valve body (18). The main pressure chamber (A) acts in the direction of opening the oil drain passage (17) against the main pressure chamber (A).
and a back pressure chamber (B) that applies pressure to the valve body (18) to block the drain oil passage (17), and allows pressure oil from the main oil passage (15) to flow into the back pressure chamber (B). The operating conditions and the back pressure chamber (B
) A solenoid valve (23) that can be switched to a state where oil is sent out.
A control valve structure comprising: and a throttle section (20) that suppresses the flow of oil sent out from the back pressure chamber (B).