Solenoid valve

A solenoid valve wherein a valve sleeve and a solenoid case can easily be formed coaxially and manufacturing costs are reduced. The solenoid valve of the present invention comprises a valve sleeve 41 provided with a spool 60 axially movable in said valve sleeve 41, a solenoid case 21 mounted to a case mounting groove 43 formed near an axial rear end of said valve sleeve 41, and a molded body 23 mounted inside said solenoid case 21 and provided with a coil 22 in said molded body 23, and a case opening portion 25 formed at an axial end of said solenoid case 21 is engaged with said case mounting groove 43, and a concave portion 29 is formed at an axial end of said molded body 23 and said axial rear end of said valve sleeve 41 is fitted to said concave portion 29.

TECHNICAL FIELD

The present invention relates to a solenoid valve preferably applied to hydraulic control, for example, for a hydraulic machinery and the like.

BACKGROUND ART

A conventional solenoid valve, for example, as shown in Japanese Patent Laid Open No. 2002-228036 (Patent Document 1), when a valve sleeve is fixed to a solenoid case, a flange shape convex portion is formed on the valve sleeve and a caulking piece provided on the solenoid case is caulked to the flange shape convex portion to fix it.

The solenoid valve having such constitution, there has been a disadvantage that, in order to form the flange shape convex portion on the valve sleeve, a diameter of the valve sleeve becomes larger and volume and weight of material of the valve sleeve also become larger. Also, since the valve sleeve and the solenoid case are fixed by caulking the caulking piece to the flange shape convex portion, there is risk that the valve sleeve rotates in a circumferential direction, and, that is, there is a disadvantage in fixing strength in a circumferential direction.

Therefore, when the flange portion is formed so as to fix to an electromagnetic portion as a conventional structure, since a diameter of aluminum material becomes larger, and, also in view of processing, since processing man-hours increase due to increase of portions to be cut, it has been disadvantageous in view of costs of manufacturing components. For this reason, in the valve sleeve with the flange portion made of aluminum, the valve sleeves is manufactured generally and commonly by forming an approximate shape by die casting, and then, completing it by cutting work.

Also, as shown in Japanese Patent Laid Open No. 2005-054974 (Patent Document 2), there is a solenoid valve wherein the valve sleeve and the solenoid case are fixed by using an engaging member.

In the solenoid valve having such constitution, since a number of components increases due to usage of the engaging member, there has been a disadvantage that manufacturing costs increase and assembling processes become complex.

Patent Document 1: Japanese Patent Laid Open No. 2002-228036

Patent Document 2: Japanese Patent Laid Open No. 2005-054974

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

The present invention has been made by considering above problems, a purpose thereof is to provide a solenoid valve wherein a valve sleeve and a solenoid case can easily be formed coaxially and manufacturing costs are reduced.

Means for Solving the Problem

In order to achieve the above purpose, a solenoid valve of the present invention is a solenoid valve comprising a valve sleeve provided with a spool axially movable in the valve sleeve, a solenoid case mounted to a case mounting groove formed near an axial rear end of the valve sleeve, and a molded body mounted inside the solenoid case and provided with a coil in the molded body, wherein a case opening portion formed at an axial end of the solenoid case is engaged with the case mounting groove, and a concave portion is formed at an axial end of the molded body and the axial rear end of the valve sleeve is fitted to the concave portion.

In the solenoid valve according to the present invention, the case opening portion formed at an axial end of the solenoid case is engaged with the case mounting groove formed near an axial rear end of the valve sleeve, so that the valve sleeve cannot be pulled out from the solenoid case. Also, the axial rear end of the valve sleeve is fitted to the concave portion formed at the axial end of the molded body in the solenoid case, so that coaxial properties of the valve sleeve, the solenoid case and the molded body are secured, and the valve sleeve is fixed in a rotating direction, and thus a rotating position is determined. Further, by having such constitution, the valve sleeve and the solenoid case are fixed without using any engaging member and the like, so that material costs can be reduced to manufacturing costs can be reduced.

Preferably, the case opening portion has a shape whose diameter in a first direction is longer than a diameter in a second direction, the axial rear end of the valve sleeve is formed as a shape which can be inserted into the case opening portion, and the case mounting groove is a groove that an edge portion of the case opening portion in the second direction is engaged with.

By forming the case opening portion and the axial rear end of the valve sleeve with such constitutions, and by forming the case mounting groove as a groove that the edge portion in the second direction at the case opening portion is to be engaged with, when the valve sleeve is rotated, for example, as 90° to the solenoid case, the edge portion in the second direction at the case opening portion is engaged with the case mounting groove, so that the valve sleeve cannot be pulled out from the solenoid case.

Preferably, a connector portion is formed on an outer circumference of the molded body, and the connector portion is fitted to a cutaway portion formed on the solenoid case. Also, preferably, the connector portion is formed integrally with the molded body.

By making such constitution, the molded body is caused not to rotate to the solenoid case.

Preferably, a center post is arranged inside the molded body, and a tip end of the center post is inserted inside a diameter bore formed in an axial direction in the valve sleeve.

By making such constitution, coaxial properties of the valve sleeve, the molded body and the solenoid case can be secured and backlash can be prevented.

Preferably, a lower plate is integrally formed with the molded body, and the tip end of the center post is inserted into an alignment bore formed on the lower plate.

By making such constitution, the coaxial properties of the valve sleeve, the molded body and the solenoid case can be secured more preferably and the backlash also can be prevented more preferably.

Also, in order to achieve the above purpose, a method for manufacturing a solenoid valve according to the present invention comprises steps of: inserting a case mounting groove formed near an axial rear end of a valve sleeve into a case opening portion formed at an axial end of a solenoid case; rotating the valve sleeve relatively to the solenoid case in a circumferential direction of the valve sleeve so as to be engaged with the case mounting groove to the case opening portion; and inserting a molded body inside the solenoid case so as to fit a concave portion of the molded body to an axial rear end of the valve sleeve.

By the method for manufacturing a solenoid valve having such steps, it is easy to assemble the valve sleeve and the solenoid case coaxially, and the manufacturing costs can be reduced.

BEST MODE FOR CARRYING THE INVENTION

Below, the present invention will be explained on the basis of embodiments shown in drawings.

FIG. 1is a cross sectional view of a solenoid valve according to an embodiment of the present invention,FIG. 2AandFIG. 2Bare cross sectional views showing a step for mounting a solenoid case to a valve sleeve shown inFIG. 1.FIG. 3AtoFIG. 3Care main section enlarged views precisely showing a case mounting groove and a case opening portion shown inFIG. 2AandFIG. 2B,FIG. 4AandFIG. 4Bare cross sectional views showing a step for mounting a molded body in the solenoid case shown inFIG. 1,FIG. 5is a plane view of the molded body shown inFIG. 4AandFIG. 4B,FIG. 6AandFIG. 6Bare cross sectional views showing a step for mounting a center post to the molded body shown inFIG. 1.FIG. 7is a cross sectional view showing a step for mounting a rod, a plunger and an end plate to the center post of the solenoid valve shown inFIG. 1.

As shown inFIG. 1, a solenoid valve10according to the embodiment of the present invention is a spool type solenoid valve to control hydraulic pressure, for example, for an automatic transmission and the like for a vehicle.

The solenoid valve10comprises a solenoid portion (linear solenoid)20as an electric driving portion, a valve body40and a retainer45. The solenoid portion20is mounted at one end (rear end) in an axial direction Z of the valve body40, and the retainer is mounted at another end (tip end) in the axial direction Z of the valve body40. The solenoid portion20comprises a molded body23provided with a coil22internally, a center post27, a spacer36, a side ring37, a rod26and a plunger24in a solenoid case21.

The coil22is integrally formed so as to be embedded inside the molded body23mounted on an inner circumferential side of the solenoid case21, and control voltage is provided from a connector which projects toward an outside of the solenoid case21to the coil22. The coil22generates a magnetic field with a desired strength and a desired direction and makes the plunger24generate driving force in the axial direction Z, so that the driving force is transmitted to the spool60via the rod26to becomes force for moving a spool60in an axial direction.

The side ring37, the spacer36and the center post27are fixed on an inner circumferential side of the molded body23. A plunger24is axially movably arranged on an inner circumference of the side rings37, and the rod26is axially movably arranged on an inner circumference of the center post27. The plunger24and the rod26are connected in a separable condition, a tip end of the rod26is in contact with a rear end of a spool shaft61of the spool60. The spacer36is a component composed by non-magnetic material so as to form a magnetic gap.

At a tip end of the spool60, a rear end of a spring42equipped inside the retainer45is coupled, and the spool60is constantly pressed to the rod26direction of the plunger24by elastic force of the spring42. Note that, the retainer45is caulked to a tip end of the valve sleeve41of the valve body40.

Although material of the valve sleeve41is not particularly limited, for example, aluminium, Fe, resin and the like are exemplified. Although material of the retainer45is not particularly limited, for example, Fe, stainless, resin and the like are exemplified.

On the valve sleeve41, an inlet port, a control port, a drain port and a feedback port, although they are not shown in the drawings, are sequentially formed from the tip end side to the rear end side as openings through a circumferential wall of the valve sleeve41.

The inlet port is a port that a controlling fluid (e.g., operating oil) supplied by a pump from a tank not shown in the drawings is flowed into. The control port is a port that the control fluid to a fluid requestor (load) such as the automatic transmission not shown in the drawings is supplied from. The feedback port and the control port communicate each other on the outside of the solenoid valve10, a part of the control fluid flowed out from the control port flows into the feedback port.

The spool60is almost arranged in the center of the valve sleeve41in a movable condition in the axial direction Z, and consists of a spool shaft61and first to third lands63to65formed in cylindrical shapes.

The first to third lands63to65are integrally formed with the spool shaft61sequentially from the spring42side end portion of the spool60in the axial direction Z with predetermined spaces.

Outer diameters of the first to third lands63to65are larger than an outer diameter of the spool shaft61. Also, though the outer diameters of the first land63and the second land64are almost same, the outer diameter of the third land65is smaller than the outer diameters of the first land63and the second land64.

On the inside of the valve sleeve41, a feedback chamber67is formed between the second land64and the third land65. Since there is a difference between the outer diameter of the second land64and the outer diameter of the third land65, areas on which the control fluid by the feedback acts to the spool60are different.

the feedback chamber67acting to the spool60. Therefore, with respect to the control fluid flowed out from the control port, desired output pressure can be obtained by a balance among three forces which are a feedback force generated by the difference of the areas (difference of the outer diameters of the land64and the land65), a spring force by the spring42and an electromagnetic force changed by amplitude of the electric current. For example, in a case of a type of control valve that the more the electric current is supplied to the solenoid portion20, the less the output pressure becomes, the balance of the three forces can be shown by the following formula;
[spring force]=[output pressure(=feedback force generated by outer diameters difference of lands)]+[electromagnetic force]  (1).

Also, in a case of a type of control valve that the less the electric current is supplied to the solenoid portion20, the more the output pressure becomes, the balance of the three forces can be shown by the following formula;
[spring force]+[output pressure(=feedback force generated by outer diameters difference of lands)]=[electromagnetic force]  (2).

One end of the spool60in the axial direction Z is in contact with the spring42, and the other end of the spool60in the axial direction Z is in contact with the rod24. Therefore, to the spool60, other than a pressing force (feedback force) of the control fluid in the feedback chamber67, a pressing force of the spring42(spring force) and a pressing force (electromagnetic force) due to the movement of the plunger24via the rod24are transmitted. The spool60slidingly moves in the valve sleeve41in the axial direction Z by these pressing forces.

In the solenoid valve10having such constitution, the spool60rests at a position where the pressing force (spring force) of the spring42, the pressing force (electromagnetic force) of the plunger24which presses the spool60caused by magnetic suction force in a magnetic field originated by an electric current supplied to the coil22, and the pressing force (feedback force) the spool60receives based on pressure of the control fluid in the feedback chamber67are balanced. Precisely, though these are statically balanced at the position to be balanced, practically, there are controlled by opening and closing the inlet port and the drain port frequently.

A position of the spool60in the valve sleeve41is controlled by the above mentioned force, and the inlet port and/or the drain port are opened or closed in desired states.

Also, an amount of the control fluid which flows from the inlet port51to the outlet port52is determined by an opening amount of the inlet port51. The opening amount of the inlet port51is determined by a position of the spool60on the inside of the spool41.

In the solenoid valve10configured like this, the coil22generates the magnetic field with desired strength and desired directions by supplying the electric current from a controlling circuit not shown in the drawings to the coil22of the solenoid portion20, so that the plunger24is moved by the magnetic suction force of the magnetic field, and the spool60moves in the valve sleeve41of the valve body40.

Therefore, in a case that an amount of the electric current supplied to the coil22increases and larger magnetic suction force is caused to act on the plunger24, the spool60moves to the spring42side in the valve sleeve41of the valve body40. When the spool60moves to the spring42side in the valve sleeve41, an amount of the control fluid flowing from the control port to the drain port increases.

On the other hand, in a case that an amount of the electric current supplied to the coil22is caused as smaller and the magnetic suction force which acts on the plunger24is reduced, the spool60moves to the solenoid portion20side in the valve sleeve41. When the spool60moves to the solenoid portion20side in the valve sleeve41, an amount of the control fluid flowing from the inlet port to the control port.

Next, a method for manufacturing the solenoid valve10will be explained.

As shown inFIG. 2A, a case mounting groove43is formed near a rear end in the axial direction Z of the valve sleeve. Also, as shown inFIG. 3A, the case mounting groove43is a groove extending in the circumferential direction. The case mounting groove43is engaged with a case opening portion25formed at an end in the axial direction Z of the solenoid case21as shown inFIG. 2B.

As shown inFIG. 3B, at the end in the axial direction Z of the solenoid case21, the case opening portion25with a shape whose diameter in a first direction X is longer than a diameter in a second direction Y. Also, as shown inFIG. 3A, a shape of the rear end41ain the axial direction Z of the valve sleeve41is formed almost the same as the case opening portion25. Therefore, as shown inFIG. 3C, the real end41A of the valve sleeve can be inserted into the case opening portion25. And then, by rotating the valve sleeve41relatively 90 degrees to the solenoid case21, the edge portion25ain the second direction in the case opening portion25is engaged with the case mounting groove43, so that the valve sleeve41cannot be pulled out from the solenoid case21.

Next, as shown inFIG. 4A, the molded body23is inserted inside the solenoid case21. At the tip end in the axial direction Z of the molded body23, a concave portion29is formed. As shown inFIG. 5, a shape of the concave portion29is almost the same as the rear end41aof the valve sleeve. Also, a lower plate35is integrally formed inside the molded body23, and an alignment bore30is formed at inside end portion in a diametrical direction on the lower plate. As shown inFIG. 4B, the rear end41aof the valve sleeve41is fitted to the concave portion29, so that coaxial properties of the valve sleeve41, the solenoid case21and the molded body23are secured, and the valve sleeve is fixed in a rotating direction, and thus a rotating position is determined.

Also, a cutaway portion31is formed on the solenoid case21. A connector28integrally formed on an outer circumference of the molded body23is fitted to the cutaway portion31, so that the molded body23is caused not to rotate to the solenoid case21.

After that, as shown inFIG. 6AandFIG. 6B, a center post27is arranged inside the molded body23. The center post27comprises a projection portion27aprojecting in the axial direction Z, and the projection portion27ais inserted into the insides of a diameter bore44and the alignment bore30, so that the diameter bore44and the alignment bore30are caused in the condition that they have the same inner circumferential faces. As a result, the coaxial properties of the valve sleeve, the molded body and the solenoid case can be secured more efficiently and backlash can be prevented.

Finally, as shown inFIG. 7, a side ring37, a spacer36, a rod26, a plunger24and an end plate33are mounted inside the molded body23, so that the solenoid valve10of the present embodiment is manufactured.

The solenoid valve10of the present embodiment, by having above mentioned constitution, it is easy to assemble the valve sleeve41and the solenoid case21coaxially, and the manufacturing costs can be reduced.

Note that, the present invention is not limited to the above mentioned embodiment, it can be modified within a scope of the present invention.