JPH0122963Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cylinder control device devised for remotely controlling an engine governor, etc., which can be applied to engine governor control, variable pump flow rate control, etc.

FIG. 1 shows the configuration of a conventional cylinder control device, in which a cylinder 5 is connected to an electrically controlled solenoid valve 6.
, a position detector 9, a piston 5a, and a return spring 5b. The solenoid valve 6 is actuated by a current controlled by a controller 8 to move the piston 5a, and the position detector 9 and comparator 7 act to stop the piston 5a at an arbitrary position.

However, the conventional cylinder control device shown in FIG. 1 requires a position detector 9 and a comparator 7 in order to control the cylinder 5 as described above, resulting in a complicated structure and high cost. Ta.

In the conventional speed governor proposed in Japanese Patent Publication No. 47-47051, the pressure oil from the pump enters the hydraulic chamber through a solenoid valve, and then returns to the tank port through an orifice. When compared with the conventional example shown in Fig. 4, it corresponds to an arrangement in which the variable orifice 2 (electromagnetic valve) and orifice 3a in Fig. 4 are reversed, and is functionally the same as the conventional example shown in Fig. 4. , and the pressure Pa in the hydraulic chamber is P _a = δ″ (P ₁ − P ₀ ) − _{P 0.} If the solenoid valve and orifice are the same as those of the present invention shown in Fig. 2, then The flow coefficient δ″≒δ, which is exactly the same as the conventional example shown in FIG.

As a result, pressure fluctuations become large and unstable, requiring feedback from a rotational speed detector and a comparator, resulting in disadvantages such as a complicated and expensive structure.

The present invention was proposed in order to eliminate the above-mentioned conventional drawbacks, and in a control device that moves the piston of a cylinder to an arbitrary position, a fixed orifice is provided at the hydraulic oil inlet of the pressure chamber of the cylinder. A variable orifice is provided at the outlet, and a pulse signal is applied to the variable orifice to intermittent the oil flowing through the fixed orifice to control the pressure in the pressure chamber. It is an object of the present invention to provide a cylinder control device that has a simple structure and can reduce costs so as to suppress pressure fluctuations by providing an orifice.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram of a cylinder control device showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram of control pulses.

In the figure, 1 is a cylinder incorporating a return spring 1b, 1a is a piston, 2 is a solenoid valve, 3a and 3b are throttles, and 4 is a controller incorporating a pulse generator. It is possible to change the duty (the ratio of the pulse period t ₀ in Figure 3 to the time t ₁ during which the current flows).

Next, to explain the operation, when the lever of the controller 4 is moved to excite the solenoid valve 2, the solenoid valve 2 is excited by the current of its duty, the average pressure Pa of the chamber 1c increases, and the piston 1a is activated by the return spring 1b. moves to the left against the spring force F, F=Pa・s
to move to a balanced position and stop. However, s
is the cross-sectional area of the piston.

When a pulse signal is applied to solenoid valve 2, the pulse is
Since it is excited and pressure oil flows during the ON time, and does not flow during the OFF time, it can be considered as a variable orifice with a flow path area _A1 that changes depending on the duty of the pulse. Therefore, orifice 3 is installed only on the solenoid valve inlet side.
a, as shown in the circuit diagram of the explanatory diagram in Fig. 4, the average pressure P _a in the cylinder chamber 1c is the orifice pressure P a and the relief pressure of the circuit is P ₁ and the pressure of the drain port is P ₀ . 3a and the variable orifice 2, the pressure is intermediate between _P1 and _P0 , and by changing the duty of the solenoid valve 2 and changing the flow path area, it can take an arbitrary value. Furthermore, considering the flow coefficient δ including the orifice 3a and the variable throttle of the solenoid valve 2, the average pressure P _a changes depending on the duty.

P _a = δ (P ₁ − P ₀ ) + P ₀ Therefore, by changing the duty, change the value of P ₀ ,
It can be controlled to any position by balancing with the return spring 1b.

However, the solenoid valve 2 is turned on by the pulse.
Since it is OFF, the pressure in the chamber 1c is fluctuating, and if the rate of fluctuation is ε, then ε=P ₁ −P ₀ /P _a =1/δ+P ₀ /(P ₁ −P ₂ ). If this fluctuation rate is large, it will be difficult to control and there is a risk that vibration will occur. In addition, the vibration rate ε
is the ratio between the difference between the maximum pressure and the minimum pressure in the chamber 1c and the control pressure, and represents the magnitude of pressure fluctuation. Therefore, it is meaningless unless the comparison is made using the same value of control pressure P _a . If the orifice 3a is removed, the pressure in the chamber 1c will always be _P1 , making it impossible to control the cylinder.

Therefore, if another orifice 3b is placed in the conduit between the solenoid valve 2 and the drain port, the pressure between the solenoid valve 2 and the orifice 3b will be Since there is the same orifice 3b, P _b is higher than P ₀ , and chamber 1c
The average pressure P _b ' is a pressure between P ₁ and P _b as described above, and changes depending on the duty of the solenoid valve 2.

Also, considering the flow rate coefficient δ' as above, P _a ′
is P _a ′=δ′(P ₁ −P _b )+P _b , and similarly, the pressure fluctuation rate ε′ at this time is ε′=P ₁ −P _b /P _a =1/δ′+P _b /( P ₁ −P _b ).

Here, if we compare the magnitude of fluctuation rate ε and ε′ at the same average pressure (when P _a = P _a ′), we find that ε′/ε=δ+[P ₀ /P ₁ −P ₀ ]/δ′+[ P _b /(P ₁ −P _b
)] = δ(P ₁ −P _b )(P ₁ −P ₀ )+P ₀ (P ₁ −P _b )/δ′(P ₁ −P ₀
)(P ₁ −P _b )+P _b (P ₁ −P ₀ ).

Here, the flow coefficient is determined by the shape, so if the same solenoid valve is used, it can be considered that δ≒δ', and if we compare the numerator and denominator of the above equation, P ₁ > P _b > P ₀ . , P ₀ (P ₁ −P _b )<P _b (P ₁ −P ₀ ), ε′/ε<1, and finally ε′<ε, which means that placing the aperture 3b at the outlet reduces the fluctuation. It can be seen that the amount decreases and becomes stable.

Therefore, even with a simple structure and low cost method as in the present invention, if the orifice 3b is used, it is possible to easily control the position of the piston 1a.

As explained in detail above, in the present invention, a fixed orifice is provided at the hydraulic oil inlet of the pressure chamber of the actuator, and a variable orifice is provided at the outlet of the pressure chamber. However, this problem does not occur with the present invention, and another orifice is provided in the drain oil path between the variable orifice and the drain tank, so the rate of fluctuation of the pressure in the pressure chamber is kept small and the piston pressure is controlled. Position control can be facilitated, and the conventional rotation speed detector, position detector, comparator, etc. are not required, so the structure is simple and there is no disadvantage of high cost.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an example of a conventional cylinder control device, Fig. 2 is a circuit diagram of a cylinder control device showing an embodiment of the present invention, Fig. 3 is an explanatory diagram of control pulses, and Fig. 4 is a conventional cylinder control device. FIG. 5 is a circuit explanatory diagram of the present invention. Explanation of the main parts of the figure, 1...Cylinder, 1a...
... Piston, 2... Solenoid valve, 3a, 3b... Throttle, 4... Pulse generator.

Claims (1)

[Scope of utility model registration request] In a control device that moves the piston of a cylinder to an arbitrary position, a fixed orifice is provided at the hydraulic oil inlet of the pressure chamber of the cylinder, a variable orifice is provided at the outlet of the pressure chamber, a pulse signal is given to the variable orifice, and the A cylinder control device, characterized in that the pressure in the pressure chamber is controlled by intermittent oil flowing through the orifice, and another orifice is provided in a drain oil path between the variable orifice and the drain tank.