JP4811386B2 - Shaft support structure - Google Patents

Description

  The present invention relates to a shaft support structure and, for example, relates to a technique suitable for use in an electromagnetic valve that transmits an axial output of an electric actuator (such as a linear solenoid) to a valve body of a valve device.

As an example of adopting a shaft support structure, an electromagnetic valve including a shaft that transmits a driving force of a plunger of a linear solenoid to a valve body of a valve device is known (for example, see Patent Document 1).
The electromagnetic valve disclosed in Patent Document 1 includes a bearing that supports a shaft so as to be slidable in the axial direction. A space α on one side in the axial direction of the bearing is surrounded by a bearing and a plunger. The volume varies according to the displacement of the plunger.
The space β on the other side of the bearing in the axial direction is a chamber (oil discharge chamber, breathing chamber, etc.) that communicates with the outside, and the sliding between the shaft and the bearing is possible in order to allow the volume variation of the space α. A breathing groove that connects the space α and the space β is formed on the surface.

The breathing groove is formed on the inner peripheral surface of the bearing or the outer peripheral surface of the shaft.
(A) When the breathing groove is formed on the outer peripheral surface of the shaft, since the groove processing is performed on the outer peripheral surface of the shaft exposed to the outside, processing such as general cutting and grinding is possible.
(B) However, when the breathing groove is formed on the inner peripheral surface of the bearing, the inner peripheral surface of the hole must be grooved, and the cutting process for forming the breathing groove is difficult, and the processing cost is low. There is a problem that becomes high.

On the other hand, a linear groove or a spiral groove along the axial direction has been proposed as the shape of the breathing groove. However, the shape of the breathing groove in the prior art has the following problems.
(C) When the breathing groove is a straight groove, the amount of eccentricity of the shaft core with respect to the shaft core of the bearing is increased. Specifically, when a linear groove is formed on the inner peripheral surface of the bearing, a part of the outer peripheral surface of the shaft fits into the linear groove when viewed from the axial direction, resulting in an increased amount of shaft eccentricity. . In addition, even when a linear groove is formed on the outer peripheral surface of the shaft, since a part of the outer peripheral surface of the shaft is recessed by the linear groove when viewed from the axial direction, the linear groove matches the inner peripheral surface of the bearing. The amount of eccentricity of the shaft becomes large (for example, see FIG. 2 of Patent Document 1).
When the amount of eccentricity of the shaft increases, the sliding backlash of the shaft increases, which causes a poor sliding of the shaft.
(D) On the other hand, when the breathing groove is a spiral groove (see, for example, Patent Documents 1 and 2), a recess due to the provision of the breathing groove does not occur when viewed from the axial direction. For this reason, even if a breathing groove is provided, an increase in the amount of eccentricity of the shaft can be prevented.

For the reasons (a) to (d) above, as shown in FIG. 3, by forming the spiral groove 7 on the outer peripheral surface of the shaft 1, it is possible to obtain ease of processing and prevention of eccentricity of the shaft 1. .
However, when the shaft 1 slides in the axial direction, the spiral groove 7 formed on the outer peripheral surface of the shaft 1 has first and second bearing edges 4 and 5 at both ends of the bearing 2 (corner portions at the ends of the bearing 1). ). For this reason, when the shaft 1 is displaced in the axial direction, the edge of the spiral groove 7 is the first and second bearing edges 4 and 4 in the sliding ranges A and B of the shaft 1 with respect to the first and second bearing edges 4 and 5. 5 is likely to be caught on the shaft 1 and may cause a sliding failure of the shaft 1.
In particular, when a shape defect such as a cutting burr occurs in the first and second bearing edges 4 and 5 and the spiral groove 7, there is a high possibility that a sliding failure of the shaft 1 occurs.
JP 2004-301295 A JP-A-11-166635

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a shaft support structure that can easily process a breathing groove, prevent eccentricity of the shaft, and can prevent catching by the breathing groove. is there.

[Means of claim 1]
Since the breathing groove (spiral groove + first and second straight grooves) in the shaft support structure employing the means of claim 1 is provided on the outer peripheral surface of the shaft, the processing cost for forming the breathing groove is reduced. Can be suppressed.
In addition, since the breathing groove in the axial range C is a spiral groove formed on the outer peripheral surface of the shaft, a dent due to the provision of the breathing groove does not occur when viewed from the axial direction. For this reason, even if a breathing groove is provided on the sliding surface of the bearing and the shaft, the eccentric amount of the shaft due to the provision of the breathing groove is not increased.
Furthermore, the breathing grooves in the sliding ranges A and B are formed on the outer peripheral surface of the shaft and are first and second linear grooves along the axial direction of the shaft, and therefore intersect with the first and second bearing edges. Does not have an edge. For this reason, even if the first and second linear grooves slide in the sliding ranges A and B, the first and second bearing edges and the first and second linear grooves are not caught, and the shaft does not slide properly. Not invited.
That is, by adopting the means of claim 1, it is possible to obtain “ease of processing”, “prevention of shaft eccentricity”, and “prevention of catching by the breathing groove”, and the cost of the shaft support structure is low. Reliability can be increased.

[Means of claim 2]
The shaft support structure adopting the means of claim 2 is characterized in that at least one of the first straight groove and the second straight groove in the means of claim 1 is formed on the outer peripheral surface of the shaft and between the inner peripheral surface of the bearing. It is replaced with a small diameter part that forms a gap.
Since the small diameter portion is provided on the outer peripheral surface of the shaft, “ease of processing” can be obtained.
Further, since the breathing groove in the axial direction range C is a spiral groove, “shaft eccentricity prevention” can be obtained.
Furthermore, since the small diameter portion forms a gap with the inner peripheral surface of the bearing, the small diameter portion does not catch on the first and second bearing edges, and “preventing catching by the breathing groove” can be obtained.
That is, by adopting the means of claim 2, as in the means of claim 1, “ease of processing”, “preventing shaft eccentricity”, and “preventing catching by the breathing groove” can be obtained. The reliability of the shaft support structure can be increased at low cost.

The shaft support structure has a cylindrical bar shape, and includes a shaft that is reciprocated in the axial direction within a predetermined range, and a bearing that slidably supports the outer peripheral surface of the shaft.
Here, the space on one side in the axial direction of the bearing is α,
The space on the other side in the axial direction of the bearing is β,
The sliding range of the shaft relative to the first bearing edge at one axial end of the bearing is A,
The sliding range of the shaft relative to the second bearing edge at the other axial end of the bearing is B,
Let C be the axial range of the shaft between the sliding range A and the sliding range B and not overlapping each of the sliding range A and sliding range B.

The shaft support structure in the best mode includes a breathing groove that communicates the space α and the space β between the shaft and the bearing.
The breathing groove in the axial range C is a helical groove formed on the outer peripheral surface of the shaft.
The breathing groove in the sliding range A is a first linear groove that is formed on the outer peripheral surface of the shaft and extends along the axial direction of the shaft that communicates the space α with one end of the spiral groove.
The breathing groove in the sliding range B is a second straight groove formed on the outer peripheral surface of the shaft and extending along the axial direction of the shaft communicating with the space β and the other end of the spiral groove.
Note that at least one of the first linear groove and the second linear groove may be replaced with a small diameter portion that is formed on the outer peripheral surface of the shaft and forms a gap between the inner peripheral surface of the bearing.

A first embodiment will be described with reference to FIG.
A hydraulic circuit of an automatic transmission (AT) or a variable valve timing device (VVT) of an automobile is equipped with an electromagnetic valve that performs hydraulic pressure switching adjustment.
A solenoid valve is a combination of a valve device (open / close valve, three-way valve, four-way valve, five-way valve, etc.) and a linear solenoid (electromagnetic actuator) that drives this valve device. A shaft 1 for transmitting a directional output to the valve body of the valve device is provided.

The shaft 1 is a metal member having a cylindrical bar shape, and is reciprocally driven in the axial direction within a predetermined range by the operation of the linear solenoid and the biasing force (spring, fluid pressure, etc.) of the biasing means.
Specifically, the shaft 1 is displaced integrally with the plunger (movable element) of the linear solenoid and the valve body of the valve device. When the shaft 1 is provided integrally with the plunger on one end side of the shaft 1, the shaft 1 Is coupled to the plunger by press fitting or the like, the shaft 1 may be pressed against the plunger. Further, on the other end side of the shaft 1, the shaft 1 may be provided integrally with the valve body, the shaft 1 may be coupled to the valve body by press-fitting, or the valve body may be pressed against the shaft 1.

The electromagnetic valve includes a shaft support structure that supports the shaft 1 so as to be slidable in the axial direction. The shaft support structure includes a bearing 2 made of a metal member that slidably supports the outer peripheral surface of the shaft 1 that transmits the driving force of the linear solenoid to the valve body. The bearing 2 may be provided in a valve housing of a valve device or may be provided in a linear solenoid stator.
The bearing 2 includes an insertion hole 3 through which the shaft 1 passes in the axial direction. The outer peripheral surface of the shaft 1 is slidably supported by the inner peripheral surface of the insertion hole 3.

Spaces are formed on both sides of the bearing 2 in the axial direction. A space on one side of the bearing 2 in the axial direction (a space surrounded by the bearing 2 and the plunger) is α, and a space on the other side in the axial direction of the bearing 2 ( The space communicating with the outside on the valve device side) is referred to as β.
Further, the sliding range of the shaft 1 with respect to the first bearing edge 4 at one end in the axial direction of the bearing 2 (the end of the insertion hole 3 on the side close to the plunger) is A, and relative to the second bearing edge 5 at the other axial end of the bearing 2. The sliding range of the shaft 1 is B, the axial range of the shaft 1 between the sliding range A and the sliding range B in the axial direction and not overlapping each of the sliding range A and the sliding range B is C. Called.

The space α on the plunger side is a space surrounded by the bearing 2 and the plunger, and the volume varies according to the displacement of the plunger.
On the other hand, the space β on the valve device side is a chamber (oil discharge chamber, breathing chamber, etc.) communicating with the outside.
In the electromagnetic valve, a breathing groove that communicates the space α and the space β is formed on the sliding surface between the shaft 1 and the bearing 2 in order to enable the volume variation of the space α.

The breathing groove shown in this embodiment is provided as shown below.
The breathing groove is formed on the outer peripheral surface of the shaft 1 and communicates the space α and the space β.
The breathing groove in the axial range C is a spiral groove 7 formed on the outer peripheral surface of the shaft 1. That is, both ends of the spiral groove 7 do not reach the sliding range A and the sliding range B as shown in FIG.
The breathing groove in the sliding range A is a first linear groove 8 that is formed on the outer peripheral surface of the shaft 1 and communicates with the space α and one end of the spiral groove 7 along the axial direction of the shaft 1. There are no edges that intersect. Specifically, the end on the space α side of the first linear groove 8 is provided so as to always communicate with the space α in the sliding range of the shaft 1, and the space α and one end of the spiral groove 7 are always communicated. To do.
The breathing groove in the sliding range B is a second linear groove 9 that is formed on the outer peripheral surface of the shaft 1 and communicates with the space β and the other end of the spiral groove 7 along the axial direction of the shaft 1, and the second bearing edge There is no edge crossing 5. Specifically, the end on the space β side of the second linear groove 9 is provided so as to always communicate with the space β in the sliding range of the shaft 1, and the space β and the other end of the spiral groove 7 are always connected. Communicate.

The electromagnetic valve shown in the first embodiment has the following effects by adopting the shaft support structure described above.
Since the breathing groove that communicates the space α and the space β is the spiral groove 7 on the outer peripheral surface of the shaft 1 and the first and second linear grooves 8 and 9, it is formed by performing groove processing on the outer peripheral surface of the shaft 1. can do. That is, the spiral groove 7 forming the breathing groove and the first and second linear grooves 8 and 9 can be formed by general processing such as cutting and grinding. As a result, the processing of the breathing groove is facilitated compared to the case where the breathing groove is formed on the inner peripheral surface of the bearing 2, and the processing cost when forming the breathing groove can be suppressed.
-Since the breathing groove in the axial direction range C is the spiral groove 7 formed in the outer peripheral surface of the shaft 1, the dent by having provided the breathing groove does not occur seeing from the axial direction. For this reason, even if a breathing groove is provided on the sliding surface of the bearing 2 and the shaft 1, the eccentric amount of the shaft 1 is not increased due to the provision of the breathing groove. Thus, since the amount of eccentricity of the shaft 1 is not increased, it is possible to prevent the occurrence of sliding play and the occurrence of sliding failure of the shaft 1 due to the increase of the amount of eccentricity of the shaft 1. -Since the breathing grooves sliding in the sliding ranges A and B are the first and second linear grooves 8 and 9 along the axial direction, the edges intersecting the first and second bearing edges 4 and 5 are formed. do not have. Therefore, even if the first and second linear grooves 8 and 9 slide in the sliding ranges A and B, the first and second bearing edges 4 and 5 and the first and second linear grooves 8 and 9 There is no catch, and the occurrence of poor sliding of the shaft 1 due to the catch does not occur.

  That is, by adopting the present invention in a solenoid valve, it becomes possible to achieve “ease of processing”, “preventing eccentricity of the shaft 1”, and “preventing catching by the breathing groove”, and the reliability of the shaft support structure at low cost. Can increase the sex. That is, the reliability of the solenoid valve can be increased at low cost.

A second embodiment will be described with reference to FIG. In addition, the same code | symbol as the said Example 1 shows the same function thing.
In the second embodiment, the first and second linear grooves 8 and 9 shown in the first embodiment are replaced with first and second small diameter portions 11 and 12. The first and second small diameter portions 11 and 12 are formed on the outer peripheral surface of the shaft 1 and form a gap between the inner peripheral surface of the bearing 2 (the inner peripheral surface of the insertion hole 3) and the shaft. A range D of sliding on the bearing 2 on the outer peripheral surface of 1 is an inner side of the axial range C.

Specifically, the first small diameter portion 11 is not in contact with the first bearing edge 4 in the sliding range A, and is always a space α due to a gap between the first small diameter portion 11 and the inner peripheral surface of the bearing 2. And one end of the spiral groove 7 are communicated with each other.
Similarly, the second small diameter portion 12 is not in contact with the second bearing edge 5 in the sliding range B, and is always in space β due to the gap between the second small diameter portion 12 and the inner peripheral surface of the bearing 2. The other end of the spiral groove 7 is communicated.
Even if it provides in this way, the same effect as Example 1 can be acquired.

(Modification)
In the above embodiment, a linear solenoid is shown as an example of an actuator that drives the shaft 1, but an electric actuator (for example, a piezo actuator, an actuator that converts the rotation output of an electric motor into a linear output, and the like), fluid Other actuators such as a pressure actuator (for example, an actuator using hydraulic pressure or negative pressure) may be used.
In the above embodiment, an example in which the drive output of the actuator (linear solenoid in the embodiment) is given to the valve body of the valve device via the shaft 1 is shown, but the drive target (valve device in the embodiment) is limited. However, the present invention may be applied to other shaft support structures in which the shaft 1 is driven in the axial direction to communicate the spaces α and β on both sides of the bearing 2.

It is explanatory drawing of a shaft support structure, and sectional drawing in alignment with the II line (Example 1). It is explanatory drawing of a shaft support structure, and sectional drawing which follows the II-II line (Example 2). It is explanatory drawing of a shaft support structure, and sectional drawing which follows an III-III line (conventional example).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft 2 Bearing 4 1st bearing edge 5 2nd bearing edge 7 Spiral groove 8 1st straight groove 9 2nd straight groove 11 1st small diameter part 12 2nd small diameter part α Space of one side of axial direction of bearing β Bearing Space on the other side in the axial direction A The sliding range of the shaft with respect to the first bearing edge B The sliding range of the shaft with respect to the second bearing edge C Between the axial direction of the sliding range A and the sliding range B, and the sliding range A And the axial range of the shaft that does not overlap each of the sliding range B

Claims (2)

A shaft that has a cylindrical bar shape and is driven to reciprocate in the axial direction within a predetermined range;
In a shaft support structure comprising a bearing that slidably supports the outer peripheral surface of the shaft,
The space on one side in the axial direction of the bearing is α,
The space on the other side in the axial direction of the bearing is β,
A sliding range of the shaft relative to the first bearing edge at one axial end of the bearing is A,
The sliding range of the shaft relative to the second bearing edge at the other axial end of the bearing is B,
When the axial direction range of the shaft between the sliding range A and the sliding range B and does not overlap each of the sliding range A and the sliding range B is C,
The shaft support structure includes a breathing groove that communicates the space α and the space β between the shaft and the bearing,
The breathing groove in the axial range C is a spiral groove formed on the outer peripheral surface of the shaft,
The breathing groove in the sliding range A is a first linear groove that is formed on the outer peripheral surface of the shaft and that communicates with the space α and one end of the spiral groove along the axial direction of the shaft.
The breathing groove in the sliding range B is a second straight groove formed along the axial direction of the shaft that is formed on the outer peripheral surface of the shaft and communicates with the space β and the other end of the spiral groove. Shaft support structure.   The at least one of the first linear groove or the second linear groove according to claim 1 is formed on an outer peripheral surface of the shaft, and is replaced with a small diameter portion that forms a gap with the inner peripheral surface of the bearing. A shaft support structure characterized in that the shaft support structure is provided.

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