JP3268843B2 - Variable spring constant linear actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable spring constant type linear actuator capable of freely adjusting a thrust in an output shaft direction in accordance with a required spring constant by adjusting an exciting current.

[0002]

2. Description of the Related Art As shown in FIG. 4, in a conventional pressure control valve, a fixed position of a spring 2 for urging a side surface of a spool 1 in a positive direction A of spool displacement is adjusted by operating a screw 3. Has become. In this pressure control valve, the pressure P (secondary pressure) of the oil flowing against the spool 1 can be adjusted by adjusting the screw 3. Q indicates the flow of the oil.

[0003]

However, in the pressure control valve as described above, the pressure P cannot be automatically adjusted because the oil pressure P is adjusted by the screw 3.

[0004] Therefore, the present invention provides a linear spring-constant linear system that can perform high-speed and high-precision pressure control when applied to a pressure control valve by electrically setting an arbitrary pressure. It is an object to provide an actuator.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a stator having left and right coils wound around opposed left and right center yokes, and a linear motor having both ends passing through both center yokes. In a linear actuator having an output shaft supported by a bearing and a mover disposed between opposing surfaces of both center yokes and fixed to the output shaft, a right side surface of a left center yoke and a mover opposed thereto Are provided on the left side surface thereof, and the left side permanent magnets are magnetized to have mutually repelling polarities, and the left side surface of the right center yoke and the right side surface of the mover opposed thereto are magnetized to have mutually repelling polarities. The right permanent magnets are provided, respectively, and the repelling polarity of the left permanent magnets is the same as the repelling polarity of the right permanent magnets. By adjusting a current value flowing in a predetermined direction to the left and right coils, a repulsion force due to the same left and right repulsion polarities is adjusted according to a desired spring constant. This is a variable spring constant linear actuator.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional explanatory view showing an example of applying a variable spring constant type linear actuator according to one embodiment of the present invention to a pressure control valve shown in a conventional example, FIG. 2 is a graph showing its characteristics, and FIG. It is a block diagram of a control circuit.

In FIG. 1, a linear actuator 4 of this embodiment has a stator 6 having center yokes 5L and 5R opposed to each other, and penetrates both center yokes 5L and 5R, and both ends are supported by linear bearings 7L and 7R. Output shaft 8
And a mover 9 fixed to the output shaft 8 and arranged so that both end faces thereof face the side faces of the center yokes 5L and 5R, respectively. One end of the output shaft 8 is connected to the spool 1 of the pressure regulating valve body VAL.

[0008] On the side face of each of the center yokes 5L and 5R,
Each of the center yokes 5L, 5L in the moving direction of the output shaft 8
Permanent magnets 10 magnetized in opposite directions with respect to R
L, 10R are provided. Further, on the side surface of the mover 9, permanent magnets 11L and 11R magnetized in the direction opposite to the magnetization direction of the permanent magnets 10L and 10R provided on the opposed center yokes 5L and 5R are provided. Further, each center yoke 5L, 5R has a coil 12L, which adjusts the repulsive force of the mover 9 and the permanent magnet provided in the center yokes 5L, 5R, that is, the force for holding the mover 9 at the center position. 12R are provided. Each of the coils 12L and 12R is wound so that magnetic fluxes Φ _L and Φ _R are generated in the direction of the mover 9 when the exciting current I flows through the coils 12L and 12R. An auxiliary pole 13 is provided at the center of the stator 6 by the mover 9. That is, the exciting current I flows through the coils 12L and 12R in one predetermined direction.

In the linear actuator 4 having the above structure, both side surfaces of the mover 9 and the center yokes 5L, 5L
On the side of R, the permanent magnets 10L, 11 repelling each other.
Since L, 10R, and 11R are provided, the displacement and thrust characteristics are linear characteristics with the center position of the mover 9 as the origin 0 as shown in FIG. In FIG. 2, the inclination can be freely adjusted by changing the exciting current I flowing through the coils 12L and 12R. That is, in FIG. 2, the mover 9 is at its center position (origin 0).
When more to the left, the coil 12L, increasing the exciting current I flowing in the 12R to 2I ₀ twice that from I _0, thrust also can be seen to increase accordingly.

Referring to FIG. 3, in the pressure control circuit of the present embodiment, a pressure setting terminal 14 is connected to a plus (+) input terminal of a pressure comparator 15. The output terminal of the comparator 15 is the amplifier 1
6 to output the exciting current I from the amplifier 16 to the coils 12L and 12R. Pressure control valve V
The secondary side pressure of AL is detected by the pressure sensor 17, and the detected value is fed back to the minus (-) input terminal of the comparator 15.

[0011] The structure of the above pressure control circuit, setting the predetermined pressure P ₀ to the pressure setting terminal, the excitation current I so that the pressure value P which is fed back to the comparator 15 reaches the set pressure is automatically adjusted. The set pressure P ₀ can be temporally changed arbitrarily.

With the combination of the pressure control circuit, the linear actuator 4 and the pressure control valve VAL, the terminal 1
4 is set to an arbitrary pressure P ₀ , the pressure control valve V
It can be always _{P 0} the secondary pressure P of the AL. Specifically, if the pressure difference P ₀ −P is large, the amplifier 16 controls the current I so as to reduce the difference (in the example of FIG. 1, the force applied to the spool 2 is reduced). Moreover, the set pressure P
_{Since 0} can be arbitrarily changed, it can correspond to various automatic controls. For example, in a hydraulic press machine,
For example, when the maximum press pressure or the like is to be changed according to the work, the maximum press pressure is automatically adjusted to suit the information on the work.

In the above embodiment, the example in which the linear actuator 4 of the variable spring constant type is connected to the hydraulic control valve VAL has been described, but the application example of the linear actuator 4 is not limited to this. For example, the present invention is applicable to an air controller and various pressure devices and systems to which mechanical pressure is applied.

[0014]

As described above, since the present invention is a linear actuator having a variable spring constant as described in the claims, the spring constant can be electrically and arbitrarily changed. When applied to a valve, pressure control can be performed at high speed and with high accuracy.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing a linear actuator according to an embodiment of the present invention in relation to a pressure control valve.

FIG. 2 is an explanatory diagram showing displacement and thrust characteristics of the linear actuator shown in FIG.

FIG. 3 is a block diagram of a pressure control circuit that controls the linear actuator shown in FIG.

FIG. 4 is a sectional view of a conventional hydraulic control valve.

[Explanation of symbols]

 Reference Signs List 1 spool 4 linear actuator 5L, 5R center yoke 6 stator 7L, 7R linear bearing 8 output shaft 9 mover 10L, 10R, 11L, 11R permanent magnet 12L, 12R coil I exciting current

Claims (1)

(57) [Claims] 1. A left and right center yoke (5L,
5R), the left and right coils (12L, 12R) are wound around the stator (6), and both ends are supported by the left and right linear bearings (7L, 7R) through both center yokes (5L, 5R). In a linear actuator including an output shaft (8) and a mover (9) disposed between opposing surfaces of both center yokes (5L, 5R) and fixed to the output shaft (8), a left center yoke ( 5L) and left permanent magnets (10L, 11L) magnetized to polarities repelling each other are provided on the right side surface of the mover (9) and the left side surface of the mover (9) opposed thereto, respectively. The left side permanent magnet (10R, 11R) is provided on the left side surface and the right side surface of the mover (9) opposed thereto, respectively, with the right side permanent magnets (10R, 11R) magnetized to have mutually repelling polarities. 1L) The repelling polarity between the right and left permanent magnets (10R, 11R) is the same as the repelling polarity between the right-side permanent magnets (10R, 11R). The right and left coils (12L, 12R) are determined in advance. A spring constant variable linear actuator characterized in that the current value flowing in one direction is adjusted so that the repulsion force due to the same left and right repulsion polarities is adjusted according to the required spring constant.