Spool valve
A spool valve capable of suppressing deterioration of position controllability of a spool due to misalignment includes: a housing including a spool hole; a spool inserted into the spool hole of the housing so as to be movable in an axial direction; and an electric actuator configured to move the spool in the axial direction. The electric actuator includes: an electric motor configured to rotate an output shaft; a linear-motion converting mechanism including a linear-motion member configured to be linearly movable, the linear-motion converting mechanism being configured to convert a rotational motion of the output shaft into a linear motion of the linear-motion member; and a coupling member coupling the linear-motion member and the spool moves in accordance with the linear motion of the linear-motion member. The coupling member allows one of tilt and eccentricity of an axis of the spool relative to an axis of the linear-motion member.
1. A spool valve comprising:
a housing including a spool hole;
a spool inserted into the spool hole of the housing so as to be movable in an axial direction; and
an electric actuator configured to move the spool in the axial direction, wherein:
the electric actuator includes
an electric motor configured to rotate an output shaft,
a linear-motion converting mechanism including a linear-motion member configured to be linearly movable, the linear-motion converting mechanism being configured to convert a rotational motion of the output shaft into a linear motion of the linear-motion member, and
a coupling member coupling the linear-motion member and the spool such that the spool moves in accordance with the linear motion of the linear-motion member;
the coupling member allows at least one of tilt and eccentricity of an axis of the spool relative to an axis of the linear-motion member, and
the coupling member includes:
a motor-side coupling portion provided at the linear-motion member and
a spool-side coupling portion provided at the spool,
wherein the motor-side coupling portion and the spool-side coupling portion are configured to be displaceable relative to each other in two directions which are perpendicular to each other and are perpendicular to the axial direction.
2. The spool valve according to claim 1 , wherein the coupling member allows the tilt of the spool relative to the linear-motion member in all directions perpendicular to the axial direction.
3. The spool valve according to claim 2 , wherein the coupling member is constituted by a ball joint including the motor-side coupling portion, the spool-side coupling portion, and a ball interposed between the motor-side coupling portion and the spool-side coupling portion to couple the motor-side coupling portion and the spool-side coupling portion, the motor-side coupling portion and the spool-side coupling portion being configured to rotate relative to each other about a center point of the ball.
4. The spool valve according to claim 3 , further comprising a biasing mechanism configured to apply biasing force against a load received by the spool from the electric actuator in the axial direction, wherein:
the spool moves toward a first side or a second side in the axial direction from a neutral position by the load applied from the electric actuator;
the electric actuator is coupled to one of axial end portions of the spool;
the biasing mechanism applies the biasing force to the spool against the load from the electric actuator such that the spool returns to the neutral position; and
the biasing mechanism is arranged close to the other axial end portion of the spool.
5. The spool valve according to claim 2 , wherein the coupling member allows the eccentricity of the spool relative to the linear-motion member in all directions perpendicular to the axial direction.
6. The spool valve according to claim 5 , further comprising a biasing mechanism configured to apply biasing force against a load received by the spool from the electric actuator in the axial direction, wherein:
the spool moves toward a first side or a second side in the axial direction from a neutral position by the load applied from the electric actuator;
the electric actuator is coupled to one of axial end portions of the spool;
the biasing mechanism applies the biasing force to the spool against the load from the electric actuator such that the spool returns to the neutral position; and
the biasing mechanism is arranged close to the other axial end portion of the spool.
7. The spool valve according to claim 2 , further comprising a biasing mechanism configured to apply biasing force against a load received by the spool from the electric actuator in the axial direction, wherein:
the spool moves toward a first side or a second side in the axial direction from a neutral position by the load applied from the electric actuator;
the electric actuator is coupled to one of axial end portions of the spool;
the biasing mechanism applies the biasing force to the spool against the load from the electric actuator such that the spool returns to the neutral position; and
the biasing mechanism is arranged close to the other axial end portion of the spool.
8. The spool valve according to claim 1 , wherein the coupling member allows the eccentricity of the spool relative to the linear-motion member in all directions perpendicular to the axial direction.
9. The spool valve according to claim 8 , further comprising a biasing mechanism configured to apply biasing force against a load received by the spool from the electric actuator in the axial direction, wherein:
the spool moves toward a first side or a second side in the axial direction from a neutral position by the load applied from the electric actuator;
the electric actuator is coupled to one of axial end portions of the spool;
the biasing mechanism applies the biasing force to the spool against the load from the electric actuator such that the spool returns to the neutral position; and
the biasing mechanism is arranged close to the other axial end portion of the spool.
10. The spool valve according to claim 1 , further comprising a biasing mechanism configured to apply biasing force against a load received by the spool from the electric actuator in the axial direction, wherein:
the spool moves toward a first side or a second side in the axial direction from a neutral position by the load applied from the electric actuator;
the electric actuator is coupled to one of axial end portions of the spool;
the biasing mechanism applies the biasing force to the spool against the load from the electric actuator such that the spool returns to the neutral position; and
the biasing mechanism is arranged close to the other axial end portion of the spool.
11. The spool valve according to claim 1 , wherein:
the coupling member includes a ball interposed between the motor-side coupling portion and the spool-side coupling portion to couple the motor-side coupling portion and the spool-side coupling portion;
the spool-side coupling portion includes an insertion groove extending toward a first side in the axial direction and penetrating in a perpendicular direction perpendicular to the axial direction;
the ball is fitted to the insertion groove;
the motor-side coupling portion includes a projecting portion inserted into the insertion groove;
the projecting portion includes a fitting hole in which the ball is fitted; and
the motor-side coupling portion and the spool-side coupling portion are coupled to each other by the ball in such a manner that with the ball fitted in the fitting hole, the projecting portion is inserted into the insertion groove of the spool-side coupling portion.