TECHNICAL FIELD

The present invention relates to a solenoid valve that switches a communication state among multiple ports by displacing a movable iron core due to the magnetic excitation of a solenoid portion and by moving a valve plug due to the displacement of the movable iron core.

BACKGROUND ART

A known solenoid valve is configured such that magnetic excitation of a solenoid portion of a valve actuation unit displaces a movable iron core, thereby moves a valve plug in the displacement direction of the movable iron core, and switches a communication state among multiple ports.

A solenoid valve of this type, which is disclosed in PTL 1, includes a valve body in which the valve plug is accommodated and a closed-end magnetic cover that has an opening at one end. The solenoid portion of the valve actuation unit is inserted in the magnetic cover from the opening thereof. The valve body and the magnetic cover are joined to each other while a pair of engagement holes formed at opposite sidewalls of the magnetic cover at the opening engage a pair of respective locking protrusions formed at opposite side surfaces of the valve body.

When the engagement holes of the magnetic cover engage the locking protrusions of the valve body in assembling the solenoid valve, the sidewalls of the magnetic cover at the opening temporarily run up onto the locking protrusions before engagement. This may cause plastic deformation of the magnetic cover and may lead to a decrease in a fixation rigidity between the valve body and the magnetic cover after assembly, which may cause play therebetween, for example.

To prevent the plastic deformation from occurring during assembly, the magnetic cover may be formed, by pressing a sheet of a magnetic metal, such as stainless steel, so as to include a bonnet wall having spring portions. The bonnet wall having the spring portions is integrally connected to edges of the sidewalls that are positioned opposite to the opening of the magnetic cover. Accordingly, when the sidewalls of the magnetic cover are opened due to the sidewalls at the opening running up onto the locking protrusions of the valve body, the spring portions may urge respective sidewalls in the closing directions.

This joining structure between the magnetic cover and the valve body, however, may not provide sufficient fixation rigidity therebetween because the fixation rigidity depends mainly on the rigidity of the spring portions of the connection wall.

CITATION LIST

Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 2017-207158

SUMMARY OF INVENTION

Technical Problem

Accordingly, a problem is to obtain sufficient fixation rigidity (i.e., rigidity of the assembly) between the valve body and the magnetic cover in the solenoid valve in which the valve body including the valve plug for switching the communication state among multiple ports is joined, by engagement of locking protrusions and engagement holes, to the magnetic cover that accommodates the solenoid portion of the valve actuation unit for moving the valve plug.

Solution to Problem

To solve the above problem, the present invention provides a solenoid valve, which extends in an axial direction, a width direction orthogonal to the axial direction, and an up-down direction orthogonal to the axial direction and has a first end and a second end positioned opposite to each other in the axial direction. The solenoid valve includes a valve body having multiple ports inside and also having a valve plug disposed inside so as to be able to move in the axial direction and to switch a communication state among the ports. The solenoid valve also includes a valve actuation unit that includes a solenoid portion and that is connected to an end portion of the valve body near the second end and configured to move the valve plug by moving a movable iron core in the axial direction due to magnetic excitation of the solenoid portion. The solenoid valve also includes a closed-end magnetic cover having an opening at an end thereof near the first end. The solenoid valve is formed by inserting the solenoid portion into the magnetic cover from the opening and by joining the valve body and the magnetic cover to each other. The magnetic cover is formed into a box having the opening by bending a magnetic metal sheet. The magnetic cover has first and second sidewalls that extend in the axial direction and oppose each other in the width direction, a bonnet wall that integrally connects edges of the first and second sidewalls near the second end, a top wall formed in such a manner that first and second bent portion extending from respective axially extending upper edges of the first and second sidewalls are bent toward a space between the first and second sidewalls, and a bottom wall formed between axially extending lower edges of the first and second sidewalls so as to oppose the top wall in the up-down direction. The valve body and the magnetic cover are joined to each other by engagement between locking protrusions and engagement holes that are formed at a pair of side surfaces of the valve body and at the first and second sidewalls of the magnetic cover. The solenoid valve further includes a first fastening member that fastens the first and second bent portions to each other in the width direction, and a second fastening member that fastens the first fastening member and the valve body to each other in the axial direction.

In the solenoid valve, it is preferable that the first bent portion have a first locking portion, the second bent portion have a second locking portion, and the valve body have a third locking portion. It is preferable that the first fastening member have a first engagement portion to engage the first locking portion of the first bent portion, a second engagement portion to engage the second locking portion of the second bent portion, and a fourth locking portion. It is also preferable that the second fastening member have a third engagement portion to engage the third locking portion of the valve body and a fourth engagement portion to engage the fourth locking portion of the first fastening member.

In addition, it is more preferable that the locking protrusions protrude from respective side surfaces of the valve body that are positioned opposite to each other in the width direction and that the engagement holes be formed respectively at the first and second sidewalls at positions near the first end in the axial direction. The first fastening member preferably has a first mount surface that opposes the top wall of the magnetic cover formed of the first and second bent portions and also has a pair of second mount surfaces that stand upward from respective edges of the first mount surface that are opposite to each other in the width direction. The first engagement portion and the second engagement portion are preferably formed at the first mount surface, and the fourth locking portions are preferably formed at respective second mount surfaces.

In the solenoid valve, it is still more preferable that the first and second engagement portions formed in the first fastening member protrude downward from the first mount surface and be formed as L-shaped hooks that are bent toward the first end. The first and second locking portions of the first and second bent portions are preferably formed as hook-receiving holes penetrating the first and second bent portions, and the L-shaped hooks preferably engage respective opening edges, near the first end, of the hook-receiving holes by inserting the L-shaped hooks into the hook-receiving holes and by sliding the L-shaped hooks toward the first end.

Here, multiple sets of the first and second locking portions and multiple sets of the first and second engagement portions may be disposed in the axial direction.

In the solenoid valve, it is still more preferable that the third locking portion of the valve body be formed as a pair of latching hooks that protrude from a top surface of the valve body at opposite end portions thereof in the width direction and that are bent so as to face in opposite directions. The second fastening member is preferably formed as a hollow cover having an opening at a bottom thereof so as to cover the first fastening member. Latching windows that serve as the third engagement portion are preferably formed through a peripheral wall of the hollow cover at opposite positions in the width direction. In addition, a lower end surface of the peripheral wall of the hollow cover preferably abuts the top wall of the magnetic cover and the top surface of the valve body.

Here, it is preferable that the latching hooks serving as the third locking portion be integrally connected to each other by a support wall formed therebetween and that a circuit board for actuating the valve actuation unit be accommodated in the hollow cover and the circuit board be supported by the first fastening member and the support wall.

In the solenoid valve, the bonnet wall of the magnetic cover is preferably formed of a pair of spring portions that extend in the up-down direction and are connected to respective edges of the first and second sidewalls near the second end and also of an abutment portion that connects the spring portions to each other. The spring portions are preferably formed as curved walls that bulge out toward the second end from respective opposite end portions of the abutment portion in the width direction, and an end surface of the solenoid portion near the second end is preferably pressed against the abutment portion of the bonnet wall from inside.

Advantageous Effects of Invention

As described above, the solenoid valve of the present invention is formed by joining the valve body that includes the valve plug configured to switch the communication state among multiple ports to the magnetic cover that accommodates the solenoid portion of the valve actuation unit for moving the valve plug. In the solenoid valve, the magnetic cover is formed as a box by bending a magnetic metal sheet. The first and second bent portions extend from axially extending upper edges of a pair of respective sidewalls, and the top wall of the magnetic cover is formed by bending the first and second bent portions toward a space therebetween. The valve body and the magnetic cover are joined to each other by engagement between the locking protrusions and the engagement holes that are formed at a pair of the side surfaces of the valve body and at a pair of the sidewalls of the magnetic cover. The first fastening member fastens the first and second bent portions to each other in the width direction, and the second fastening member fastens the first fastening member and the valve body to each other in the axial direction.

This makes the engagement between the engagement holes and the locking protrusions more reliable, which can produce sufficient fixation rigidity (rigidity of the assembly) between the valve body and the magnetic cover.

