JPH0849783A - Motor-driven valve output shaft turning-stop mechanism - Google Patents

Abstract

PURPOSE:To reduce friction loss in the turning-stop part of an output shaft and convert the torque of a rotor efficiently into the thrust of the output shaft. CONSTITUTION:A valve part 2 and a step motor 3 are connected by a bolt 16 through a spacer 4. An output shaft 22 provided with a male screw 22a to be screwed with a female screw 21a provided at the center part of a rotor 20 is connected to a valve stem 10 through connecting mechanism 24. The connecting mechanism 24 is disposed more on the valve housing 5 side than the bearing 18 of the output shaft 22. Engaging parts are formed at coupling members 25, 26 constituting the connecting mechanism 24. A guide member 30 having locking claws 30a engaged with the engaging parts so as to regulate the rotation of the output shaft 22 while allowing the axial movement of the output shaft 22 is fixed to the valve housing 5 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a valve portion having a valve body axially reciprocating in a valve housing, and a male screw threadedly engaged with a female thread provided at the center of a rotor. The present invention relates to a rotation stop mechanism for an output shaft of a motor-driven valve having an output shaft that linearly moves by a stop mechanism and a step motor that drives the valve element.

[0002]

2. Description of the Related Art In recent years, with the development of car electronics, motor driven valves that use linear motion type motors have been used to drive intake and exhaust valves. For example, as a system for reducing harmful components such as NOx in exhaust gas discharged from automobile engines, an exhaust gas recirculation (hereinafter referred to as EGR) system for recirculating exhaust gas containing unburned gas to an intake system is available. is there. As an EGR valve used in this EGR system, one having a structure shown in FIG. 22 (a) is known (for example, Japanese Patent Laid-Open No. 4-23).
1661). In this EGR valve, a step motor 72 constituting a motor portion is fixed downward to an upper end portion of a valve housing 71 constituting a valve portion via a connecting cover 73. The valve housing 71 includes an inlet port 74a and an outlet port 74b, and a shaft 76 is supported at a position facing the output shaft 75 of the step motor 72 so as to be axially slidable via a bearing 77.
A valve body 78 is fixed to the tip of the shaft 76.
Can be moved toward and away from the valve seat 80 provided in the passage 79 by the reciprocating movement of the shaft 76.

A female screw 82 is formed inside the rotor 81 of the step motor 72, and a male screw 83 that is screwed into the female screw 82 is formed at the base end side of the output shaft 75. A stopper pin 75b is fixed to the base end of the output shaft 75, and a stopper 81a engageable with the stopper pin 75b is provided at the end of the rotor 81 so as to project. As shown in FIG. 22B, the output shaft 75 has a cross section D on the tip side from the position where the male screw 83 is formed.
Cut into a shape, and the D-cut portion 75a is the D-cut portion 7
The oil-impregnated bearing 84 having a hole 84a having the same shape as the cross-sectional shape of 5a is slidably inserted and non-rotatably supported. Then, the output shaft 75
Is reciprocated in the axial direction.

A first coupling 85 is provided at the lower end of the output shaft 75, and a second coupling 8 is provided at the upper end of the shaft 76.
6 are fixed to each other, and the couplings 85 and 86 are engaged with each other to connect the output shaft 75 and the shaft 76. A coil spring 87 is interposed between both couplings 85 and 86, and both couplings 8
5 and 86 are capable of slightly moving in the vertical direction against the biasing force of the coil spring 87. A coil spring 89 that urges the coupling 86 toward the valve housing 71 is interposed between the housing 88 of the step motor 72 and the second coupling 86.

When this EGR valve is assembled, the stopper pin 75b of the output shaft 75 is replaced by the stopper 81 of the rotor 81.
The male screw 83 is screwed into the female screw 82 to a position where it abuts against a, and in this state the valve body 78 is assembled so as to abut the valve seat 80. And that state becomes the origin (reference position),
A control device (not shown) for the EGR valve sequentially controls the demagnetization of the coils 90 of each phase of the stator with the origin as a reference, and rotates the rotor 81 by a predetermined angle.

Further, Japanese Patent Laid-Open No. 61-103077 discloses an electric valve having a structure in which a needle valve is reciprocally moved by a step motor. As shown in FIG. 23, the motor-operated valve has a valve shaft 91 having a needle-shaped valve 91a formed at the tip thereof and is integrally rotatably fixed to a rotor (rotor) 92 at an intermediate portion thereof. The valve shaft 91 has a first male screw 93 formed on the front end side and a second male screw 94 formed on the base end side. The first male screw 93 is screwed into the female screw of the bearing 96 fitted and fixed to the valve body 95, and the second male screw 94 is screwed into the stopper nut 97. The stopper nut 97 is slidably supported along a pair of pins 99 fixed to the lid 98a of the case 98. Then, when the rotor 92 rotates, the valve shaft 91 rotates integrally, and the bearing 96 and the stopper nut 97 cannot rotate. Therefore, the valve shaft rotates with the rotor 20 and approaches the valve seat 95a. Go straight to separate.

[0007]

When the D-cut portion 75a of the output shaft 75 is fitted in the hole 84a of the oil-impregnated bearing 84, D
A clearance is provided between the peripheral surface of the cut portion 75a and the wall surface of the hole 84a. Therefore, the D-cut portion 75a does not come into contact with the wall surface of the hole 84 over the entire outer circumference thereof, but comes into line contact with two corner portions of the D-cut portion 75a and the opposite side portion thereof. Further, since the D-cut portion 75a is generally formed by cutting with a milling machine, milling lines and burrs remain, and the frictional force becomes large in combination with the high contact pressure (contact pressure) due to line contact. As a result, the loss in converting the rotational force of the rotor 81 into the thrust of the output shaft increases. In addition, if the processing accuracy is poor, biting occurs and causes a malfunction. The loss decreases when the milling and burrs are removed by polishing, but the loss is still high because the basic condition of line contact is the same. In addition, the cost of polishing becomes high.

Further, since the distance from the center of the output shaft to the D-cut portion 75a is short, the D-cut portion necessary to generate a moment against rotation of the output shaft 75 against the torque applied to the output shaft 75. The force acting on 75a increases,
As a result, the friction when the output shaft 75 moves increases.
Further, since there is a clearance between the peripheral surface of the D cut portion 75a and the wall surface of the hole 84a, the output shaft 75 does not move straight while the output shaft 75 is rotated by the clearance. If the clearance is the same, this rotation angle becomes larger as the diameter of the D cut portion 75a becomes smaller. However, it is not preferable to increase the diameter of the D cut portion 75a because the step motor becomes large.

Further, when the D-cut portion 75a is processed, it is necessary to perform special processing for preventing the output shaft 75 from being deformed due to bending, which makes the processing of the output shaft 75 troublesome. On the other hand, in the motor-operated valve disclosed in Japanese Patent Laid-Open No. 61-103077, the valve shaft 91 and the rotor (rotor) 92 rotate integrally, and the rotor 92 moves forward and backward together with the valve shaft 91. Therefore, a rotation stopping mechanism for the valve shaft 91 corresponding to the output shaft 75 is unnecessary. The stopper nut 97 plays a role in smoothly moving the valve shaft 91 when the valve shaft 91 is moved to the opening side even if the needle valve 91a firmly contacts the valve seat 95a at a position where the valve shaft 91 has advanced to the closed position. It is a thing. And
The stopper nut 97 is rotatably supported by a pair of pins 99 and movably supported in the axial direction. Therefore, also in the EGR valve, it is conceivable to form a large-diameter detent portion inside the rotor 81. However, if a rotation stopping portion having a sufficiently large diameter is provided inside the rotor 81, there is a problem that the entire step motor becomes large.

The present invention has been made in view of the above problems, and an object thereof is to prevent rotation of the output shaft at a position having a diameter sufficiently larger than the diameter of the output shaft, and to prevent friction in the rotation preventing portion. An object of the present invention is to provide a detent mechanism for an output shaft of a motor-driven valve that can reduce loss and efficiently use the rotational force of a rotor as thrust on the output shaft.

[0011]

In order to achieve the above object, according to the invention as set forth in claim 1, a valve portion having a valve element axially reciprocated in a valve housing and a central portion of a rotor are provided. A motor-driven valve having a step motor for driving the valve element, the output shaft having a male screw screwed with a provided female screw, and an output shaft that linearly moves by a rotation-stopping mechanism, facing a valve housing of the step motor. A bearing that supports the output shaft is provided on the side of the output shaft, and the rotation preventing member is fixed to the valve housing side of the bearing of the output shaft, and the rotation preventing member has a radial distance from the center of the output shaft of the output shaft itself. At least one engaging portion is provided at a position larger than the maximum value up to the outer peripheral surface, and engages with the engaging portion to restrict rotation of the output shaft and to move the output shaft in the axial direction. It provided on the valve housing side or the motor housing side so as to extend along the guide portion for containers in the axial direction of the output shaft.

According to a second aspect of the present invention, a plurality of the engaging portions and the guide portions are provided at rotationally symmetrical positions about the output shaft. According to a third aspect of the present invention, in the first or second aspect of the invention, the detent member and the guide portion are formed by press working parts, and at least one of the detent member and the guide portion is bent. The formed flat surface portion constitutes a sliding portion.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the guide portion is formed integrally with a tubular cover member that covers the output shaft at the portion protruding from the bearing.

According to the invention of claim 5, claim 4 is
In the invention described in (3), the guide portion is bent and formed so as to protrude inward over the entire length of the cover member.

Further, in the invention described in claim 6,
In the invention described in (3), the guide portion is a rib bent inward along a window formed in the peripheral wall of the cover member.

According to the invention described in claim 7, claim 1
The output shaft is connected to a valve shaft having a valve element axially reciprocally moved in a valve housing via a connecting mechanism, and the engaging portion is formed at a predetermined position of the connecting mechanism. A guide that is thinner toward the tip side is integrally formed at the tip of the guide portion that extends along the axial direction of the output shaft.

According to the invention described in claim 8, claim 1
In the invention described in (1), the output shaft is connected to a valve shaft having a valve body that is axially reciprocated in a valve housing via a connecting mechanism, and the connecting mechanism is a first shaft fixed to the output shaft. The coupling member and the second coupling member fixed to the valve shaft are connected to each other with a part of their flanges overlapping, and the engaging portion is formed between the end portions of the flanges of both coupling members. Each flange is integrally formed with a guide piece that extends obliquely toward the gap.

According to the invention of claim 9, claim 1
In the invention described in (1), the output shaft is connected to a valve shaft having a valve element axially reciprocally moved in a valve housing via a connecting mechanism, and a bearing for supporting the valve shaft in the valve housing is provided via a packing. The guide portion is formed integrally with a pressing washer that presses with a pressure.

According to a tenth aspect of the invention, in the invention of the ninth aspect, the pressing washer is fixed to a support member for supporting the bearing for the valve shaft so as to sandwich the bearing.

[0020]

According to the invention described in claims 1 to 10, the output shaft is supported by a bearing provided on the side of the step motor facing the valve housing, and the engaging portion of the detent member fixed to the output shaft. Is always held in engagement with the guide portion, and its rotation is restricted. When the rotor is rotated, the output shaft is axially reciprocally moved in accordance with the forward and reverse rotations of the rotor, the valve element in the valve housing is moved, and the flow path is opened and closed. The engaging portion moves along the guide portion. Since the engaging portion is provided between the step motor and the valve housing, its position can be set so that the radial distance from the center of the output shaft is much larger than the maximum value to the outer peripheral surface of the output shaft itself. As a result, the wear loss of the detent portion is reduced, and the rotational force of the rotor is efficiently converted into the thrust of the output shaft. Further, even if the clearance between the engaging portion and the guide portion is the same as the clearance between the bearing and the output shaft, the rotation angle of the output shaft due to the clearance is small, so the hysteresis during reciprocating movement of the valve body is small. , The accuracy will improve.

According to the second aspect of the present invention, in addition to performing the same operation as described above, the plurality of engaging portions and the plurality of guiding portions are arranged at rotationally symmetrical positions, so that the guiding portion with respect to the engaging portion. The force acting from is uniform and the uneven wear of the engaging portion and the guide portion is suppressed.

The invention described in claim 3 has the same operation as the invention described in claim 1 or 2. Further, although the anti-rotation member and the guide portion are composed of press-worked parts for cost reduction, at least one of the sliding portions is a bent flat surface portion, so that the sliding resistance is reduced.

The invention described in claims 4 to 6 has the same operation as that of the invention described in claim 3. Furthermore, since the guide portion is formed integrally with the tubular cover member, the strength is increased.

The invention described in claim 7 has the same operation as the invention described in claim 1. The engaging portion is formed at a predetermined position of a connecting mechanism that connects the output shaft and the valve shaft.
During assembly, the tapered guide formed at the tip of the guide portion extending along the axial direction of the output shaft first enters the engaging portion, and the subsequent guide portion surely engages with the engaging portion. Becomes

The invention described in claim 8 has the same operation as the invention described in claim 1. The first fixed to the output shaft
The coupling member and the second coupling member fixed to the valve shaft are connected to each other in a state where a part of their flanges overlap with each other, and a gap is formed between the ends of the flanges of both coupling members. Then, at the time of assembly, the guide portion is securely guided to a position where the guide portion engages with the engaging portion while engaging with the guide piece extending obliquely toward the gap.

[0026]

【Example】

(Embodiment 1) A first embodiment in which the present invention is embodied in an EGR valve will be described below with reference to FIGS. As shown in FIG. 1, a motor-driven valve 1 as an EGR valve
Has a configuration in which the valve portion 2 and the step motor 3 are connected via a spacer 4.

A valve housing 5 constituting the valve section 2
Comprises a chamber 6 having an inlet 5a and an outlet 5b. A valve seat 7 is fitted and fixed to the inlet 5a on the chamber 6 side. A hole 5c communicating with the chamber 6 is formed in the valve housing 5 on the side facing the inlet 5a, and a support plate 9 for supporting the carbon bearing 8 is provided on the upper surface of the valve housing 5 so as to cover the hole 5c. There is. 2 support plates 9
It is composed of individual sheet metal parts, and both parts are fixed so as to sandwich the carbon bearing 8. In the chamber 6, the valve shaft 10
Is pierced through the carbon bearing 8 and the support plate 9 so as to be slidable in the axial direction, and the valve body 11 is fixed to the valve seat 7 at the first end of the valve shaft 10 so as to be able to come into contact with and separate from the valve seat 7.

On the side of the valve housing 5 facing the step motor 3, a plurality of (three in this embodiment) female screw portions 12 are formed at rotationally symmetrical positions. The spacer 4 is formed in a cylindrical shape and is fitted into the annular projection 13a formed on the cover member 13 by press fitting. Flange 14a of motor housing 14 of step motor 3
A bolt insertion hole 15 is formed at a position facing each female screw portion 12 of the valve housing 5. Then, the step motor 3 is tightened so as to penetrate the bolt insertion hole 15, the annular protrusion 13 a, the spacer 4 and the support plate 9 in a state where the support plate 9, the spacer 4 and the cover member 13 are arranged between the step motor 3 and the valve housing 5. It is connected to the valve housing 5 via bolts 16 as means.

As shown in FIG. 2A, the cover member 13
Is formed in a shape in which three portions of a bottomed tubular body are cut out, and an annular protrusion 13a is formed at a position corresponding to the cutout portion 13b. Further, as shown in FIG. 1, an inner cover 17 is fixed inside the cover member 13. The inner cover 17 is formed in a cylindrical shape with a bottom, and a housing portion 19 of the bearing 18 is formed in the center of the bottom portion thereof and a hole 17a is formed therein. Further, a total of three windows 17b are formed on the peripheral wall of the inner cover 17 at a position shifted by approximately 60 ° from the notch 13b of the cover member 13. Both the cover member 13 and the inner cover 17 are formed by sheet metal working of a metal plate (for example, a stainless plate).

As shown in FIG. 1, a rotor 20 having a female screw 21a is integrally rotatably fixed to the rotor 20 of the step motor 3. A male screw 22a to be screwed with the female screw 21a is formed on the proximal end side of the output shaft 22 of the step motor 3. The output shaft 22 has a male screw 22a.
The stop pin 23 is projected from the formation position of the base end side,
When the stop pin 23 engages with the hooking portion 21b provided on the first end of the rotating body 21, the output shaft 22 is restricted from rotating relative to the rotating body 21, that is, the rotor 20. ing. The position where the stop pin 23 engages with the hooking portion 21b is set as the reference position of the output shaft 22, and the step motor 3 is drive-controlled with the reference position as the origin. The output shaft 22 is slidably inserted into the bearing 18 so that the tip end side projects into the inner cover 17.

A first coupling member 25 constituting a connecting mechanism 24 is fixed to the tip of the output shaft 22 and a second coupling member 26 is fixed to the second end of the valve shaft 10 by welding. . Both coupling members 25 and 26 serving as rotation preventing members are formed in the same shape, and as shown in FIG. 3, they are formed at a rotationally symmetrical position of a main body 27 formed in a cylindrical shape with a bottom and an opening peripheral edge portion thereof. 3 flanges 2
8a, 28b. Each flange 28
The a and 28b are formed such that the circumferential length thereof is slightly shorter than the distance between the adjacent flanges, and both end edges thereof extend in the radial direction.
A notch 27a is formed on one side of the base portion for the.

As shown in FIGS. 1 and 2B, the coupling members 25 and 26 are fixed to the output shaft 22 and the valve shaft 10 with the main bodies 27 facing each other.
A coil spring 29 as an urging member is arranged inside the main body 27, and the notches 27a of the flanges 28a and 28b are engaged with each other so that both coupling members 25 and 26 are engaged.
The respective flanges 28a and 28b are connected in a state in which they partially overlap with each other. In this state, as shown in FIG. 5B, a predetermined gap δ serving as an engaging portion is formed between the edges of the flanges 28a, 28b opposite to the notches 27a. The gaps δ are formed at an angle of 120 ° to each other.
A hook claw 30a of the guide member 30 is slidably fitted in each gap δ. The latch claw 30a functions as a guide portion that engages with the engaging portion and restricts the rotation of the output shaft 22. Both coupling members 25 and 26 form a detent member. That is, the connecting mechanism 24 for connecting the output shaft 22 and the valve shaft 10 constitutes a part of the rotation stopping mechanism for the output shaft 22.

The guide member 30 is formed by sheet metal working, and as shown in FIG. 4, three hooks 30a are parallel to each other at the rotationally symmetrical position of the ring-shaped support piece 30b, and with respect to the support piece 30b. It is projected so as to extend vertically. Each of the latching claws 30a is formed to be thinner toward the tip end side thereof, and flat surface portions 30c which are in sliding contact with the flanges 28a and 28b are bent and formed on both sides thereof so as to extend longer than the linear movement distance of the valve body 11. Then, as shown in FIG. 1, the guide member 30 is mounted on the upper surface of the support plate 9 to the output shaft 2.
2 and the support plate 9 is fixed to the valve housing 5 by the bolts 16, so that each hook claw 30a is output shaft 22 at a predetermined position in the inner cover 17.
Are arranged so as to extend parallel to the axial direction of the.

The stop pin 23 is provided so as to project at a position where it comes into contact with the engaging portion 21b when the step motor 3 is driven a plurality of steps after the valve body 11 has come into contact with the valve seat 7. Further, as shown in FIG. 1, the valve shaft 10 is interposed between the flange 28 b of the second coupling member 26 and the inner cover 17 via the second coupling member 26.
A coil spring 31 as an urging means for urging the valve element 11 in a direction in which the valve element 11 approaches the valve seat 7 is interposed.

Next, the operation of the motor-driven valve 1 constructed as described above will be described. First, the assembly procedure will be described. When connecting the output shaft 22 and the valve shaft 10, the coupling members 25 and 26 are arranged so as to face each other with the output shaft 22 and the valve shaft 10 positioned on the same straight line. This assembly is performed with the output shaft 22 assembled to the rotating body 21. Then, after arranging the coil spring 29 inside the main body 27, as shown in FIG. 5A, the flanges 28a and 28b are located between the flanges 28b and 28a of the coupling members 26 and 25 on the opposite side. Place it at the position corresponding to. Next, the output shaft 22 and the valve shaft 10 are moved toward each other against the spring force of the coil spring 29. The flanges 28a, 28b are flanges 28 of the coupling members 26, 25 on the opposite sides of each other.
Both coupling members 25 and 26 are rotated so that the notches 27a facing each other are engaged with each other in a state of being located closer to the main body portion 27 side than b and 28a. As a result, the flanges 28a and 28b of the coupling members 25 and 26 partially overlap with each other, and a gap is formed on the side opposite to the notch 27a.

From this state, the support plate 9, the spacer 4, the cover member 13 and the flange 14a are laminated on the hole 5c side of the valve housing 5, and the bolt 16 is moved from the bolt insertion hole 15 side of the flange 14a to the female screw portion 12. The step motor 3 is screwed in and tightened and fixed to the valve portion 2. At that time, the connecting mechanism 24 is moved to the base end side of the latch claw 30a in a state where the latch claw 30a corresponds to the gaps δ at the three locations. As a result, as shown in FIG.
The flat portion 30c of "a" is brought into engagement with the end portions of the flanges 28a, 28b, the relative rotation of the coupling members 25, 26 becomes impossible, and the output shaft 22 and the valve shaft 10 are guided along the hooks 30a. Can be moved linearly.

The size of the gap δ formed between the flanges 28a and 28b of both coupling members 25 and 26 is such that the clearance between the flat surface portion 30c of the hook 30a and the end portions of the flanges 28a and 28b is as small as possible. Is set. However, since the tapered guide is formed at the tip of the latch claw 30a, the flat portion 30 of the latch claw 30 is formed.
c is securely and easily inserted into the gap δ between the flanges 28a and 28b.

Next, the operation of the motor-driven valve 1 will be described. The step motor 3 is driven from the state where the output shaft 22 is arranged at the reference position. When the step motor 3 is driven, the rotor 20 is rotated, and with the rotation of the rotor 20,
Female screw 21a of the rotating body 21 and male screw 22 of the output shaft 22
A rotational force acts on the output shaft 22 via a. However, the coupling member 2 fixed to the tip of the output shaft 22
The output shaft 22 is not rotated because the rotation of the hook 5 is prevented by fitting the hook 5 with the hook 30a. As a result, the rotational movement of the rotor 20 is converted into the linear movement of the output shaft 22, and the output shaft 22 is moved in the axial direction. With the movement of the output shaft 22, the first coupling member 25
Moves along the flat surface portion 30c of the hook 30a. When the rotor 20 rotates in the normal direction, the output shaft 22 protrudes, that is, the valve seat 7
The output shaft 22 is moved in the retracted direction, that is, in the direction away from the valve seat 7 when the rotor 20 rotates in the reverse direction.

As described above, the rotational force of the rotor 20 is regulated by the engagement between the hooks 30a and the flanges 28a and 28b, and is converted into the linear motion of the output shaft 22. At that time, the frictional force of the sliding portion reduces the efficiency in converting the rotational force into the thrust. The conversion efficiency improves as the frictional force decreases. If the distance from the center of the output shaft 22 to the engaging portion that prevents the rotation is small, the force required to prevent the rotation is large, and if the distance is large, the force required to prevent the rotation is small. Compared with the conventional one in which a part of the output shaft 22 is cut to form an engaging portion, the rotation preventing member fixed to the output shaft 22 is provided with the engaging portion, so that the center of the output shaft extends to the engaging portion. The distance will be much larger.
As a result, the frictional force acting on the engaging portion is reduced, and the rotational force of the rotor 20 is efficiently converted into the thrust of the output shaft 22.

Further, in this embodiment, both coupling members 2
5, 26 and the guide member 30 are formed of sheet metal parts, but the flat surface portion 30 is bent and formed on both sides of the hook 30a.
The flanges 28a and 28b slide while c is engaged with the flanges 28a and 28b. That is, since one of the sliding portions is a flat surface, the frictional force per unit area of the sliding portion is small and the durability is improved.

Further, since the distance from the center of the output shaft 22 to the engaging portion is large, the flat portion 30c and the flanges 28a, 28 are formed.
Even when the clearance with b is the same as the clearance between the D-cut portion of the conventional output shaft and the fitting insertion hole of the bearing, the rattling of the output shaft 22 becomes very small. As a result, the amount of movement of the valve body 11 can be controlled accurately. This is because the output shaft 22 moves linearly in response to the rotation of the rotor 20 in a state where the rotation of the output shaft 22 is blocked, and as a result, when the rotor 20 rotates while the rotation of the output shaft 22 is not blocked, Therefore, the output shaft 22 does not move linearly. Even with the same clearance, the larger the distance from the center of rotation, the smaller the angle formed with the center, and the amount of rotation of the rotor 20 and the output shaft 2
The linear movement amount of 2 corresponds to the state with high accuracy. That is, there is little play when changing the moving direction of the output shaft 22 from the open side to the closed side or from the closed side to the open side,
It is possible to control the opening and closing of valves with small hysteresis.

In FIG. 1, the valve body 11 contacts the valve seat 7 and the inlet 5
The state where it has been arrange | positioned in the closed position which closes a is shown. When the rotor 20 is driven in reverse from this state, the output shaft 22
1 is moved in the upward direction of FIG. 1 (inset direction), the valve shaft 10 is moved together with the output shaft 22 via both coupling members 25 and 26, and the valve element 11 is arranged at the open position. When the rotor 20 is driven in the forward direction from the state in which the valve body 11 is arranged in the open position, the output shaft 22 is moved in the protruding direction, the valve shaft 10 is moved together with the output shaft 22, and the valve body 11 is in the closed position. Will be placed. When the rotor 20 is further driven in the forward direction after the valve body 11 is disposed at the position where it abuts on the valve seat 7, the valve shaft 10 cannot move. However, the output shaft 22 can be moved until the flanges 28a and 28b of both coupling members 25 and 26 come into contact with the body portions 27 of the other coupling members 26 and 25. That is, FIG.
Since only the distance L shown in (b) can be moved, the rotor 2
0 can rotate without difficulty.

In this embodiment, the valve body 11 is fixed to the valve shaft 10 connected to the output shaft 22 via the connecting mechanism 24. 22 can be moved to the closed side by a plurality of steps, which increases the degree of freedom during assembly.

Connection mechanism 2 for connecting the output shaft 22 and the valve shaft 10
4 is covered and protected by the inner cover 17 and the cover member 13. Since the EGR valve controls the flow rate of high-temperature exhaust gas, the temperature of the valve housing 5 becomes high and the heat is transmitted to the step motor 3 side. However, since the valve portion 2 and the step motor 3 are connected via the spacer 4, heat transfer is suppressed. The cover member 13 serves as a heat dissipation plate in addition to the role of protecting the output shaft 22 and the connection mechanism 24. The air inside the inner cover 17 is easily replaced with the outside air through the cutout portion 13b of the cover member 13 and the window 17b of the inner cover 17 to prevent heat from being trapped inside the inner cover 17. The heat of the step motor 3 is also radiated from the cover member 13. As a result, overheating of the step motor 3 is prevented.

(Embodiment 2) Next, a second embodiment will be described with reference to FIGS.
It will be described according to 0. In this embodiment, the structure of the coupling member and the support structure for the bearings of the output shaft 22 and the valve shaft 10 are different from those of the above embodiments. The same parts as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The valve shaft 10 is slidably inserted in the carbon bearing 8 fitted in the support member 32 fitted in the hole 5c. As shown in FIG. 8, the support member 32 has bolt insertion holes 32a formed at three locations which are rotationally symmetrical.
A recess 32b is formed in the center of the support member 32, and three grooves 33 for communicating the recess 32b with the outer peripheral surface are radially arranged in a rotationally symmetrical position having a phase difference of 60 ° with the bolt insertion hole 32a. It is formed to extend.

In the guide member 30, the support piece 30b is fitted in the concave portion 32b and each hook claw 30a corresponds to the groove 33 so that the support piece 30b functions as a washer for pressing the packing 34 against the carbon bearing 8. It is fixedly attached to the support member 32 in the state of being. Support member 32 of guide member 30
As shown in FIGS. 8 (a) and 8 (b), a part of the supporting member 32 is caulked to fix the caulking portion 32c to the supporting piece 3 as shown in FIGS.
It is performed by making it protrude above 0b. Instead of caulking, inert gas arc welding such as TIG welding or MIG welding or laser welding may be used.

Bearing 3 into which the output shaft 22 is slidably inserted
5 is fitted and fixed to a support member 36 that supports the bearing 20a of the rotor 20. The cover member 37 is formed in a cylindrical shape, and is fixed to the lower surface of the support plate 36 a that supports the support member 36 by welding. Windows 37a are formed on the cover member 37 at three locations which are rotationally symmetrical.

As shown in FIGS. 9 (a) and 9 (b), the first coupling member 38 has substantially the same shape as the first coupling member 25 of the first embodiment, but the flange 28a is not cut. An engaging piece 40a is formed in a bent shape at the end edge opposite to the notch 27a. As shown in FIGS. 10A and 10B, the second coupling member 39 is the first coupling member 3
8 and the structure of the main body 39a are different. That is, the main body 39a is not cylindrical with a bottom, but is provided with an annular recess 39b that serves as a receiving portion for the coil spring 29. The flange 28b is provided with an engaging piece 4 at the end opposite to the cutout 27a.
0b is bent and formed.

Both coupling members 38 and 39 are connected in the same manner as the coupling members 25 and 26 of the first embodiment. That is, in the state where the coil spring 29 is disposed between the coupling members 38 and 39, the notches 27a are engaged with each other and the engagement pieces 40a and 40 are engaged as shown in FIG.
b are assembled so as to face each other at an interval substantially equal to the interval between the flat portions 30c of the hooks 30a. Then, the flat portion 30c is arranged between the engaging pieces 40a and 40b.

Therefore, also in this embodiment, the same operational effect as that of the first embodiment is exhibited, and the output shaft 22
The engaging pieces 40a and 40b of the flanges 28a and 28b slide on the flat surface portion 30c of the hook 30a during the reciprocating movement of. Since the end surfaces of the flanges 28a and 28b have a higher surface roughness than the flat surface portion, when the end surfaces directly contact the flat surface portion 30c, the frictional resistance becomes large. However, the engagement piece 40
When a and 40b are brought into contact with the flat surface portion 30c, they are brought into contact with each other in a portion having a small surface roughness and the contact area is increased, so that the frictional force per unit area is reduced and the durability is further improved. To do. Further, since the sliding resistance is also reduced, the load on the step motor 3 is reduced.

Further, in this embodiment, since the packing retainer and the rotation stop guide are integrally formed, the number of parts and the number of assembling steps are reduced, and the manufacturing cost is reduced. or,
In this embodiment, a groove 33 that communicates with the outside is formed on the upper surface of a support member 32 that supports the carbon bearing 8 of the valve shaft 10. Therefore, when muddy water enters the cover when an automobile equipped with the motor-driven valve 1 travels in a water pool, or when water drops adhere to the inside of the cover member 37 due to dew condensation when not in use, The water is discharged from the groove 33. As a result, maintenance becomes easy.

(Third Embodiment) Next, a third embodiment will be described with reference to FIGS.
This will be described with reference to FIG. In this embodiment, the connection mechanism 24
And the structure of the detent mechanism are different from those of the above-described embodiments. The same parts as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The valve portion 2 and the step motor 3 are connected by a bolt 16 via a spacer 41 at a predetermined interval. The valve shaft 10 is slidably inserted in the carbon bearing 8 fitted in the support member 32 fitted in the hole 5c. The cover member 42 is fixed by welding to the lower surface of a support plate 44 that supports a bearing 43 through which the output shaft 22 is slidably inserted. As shown in FIG. 14A, the cover member 42 has windows 42a at three positions which are rotationally symmetrical.
Are formed. On both sides of each window 42a, a pair of ribs 42b as guide portions of the rotation stopping mechanism are formed by bending so as to extend inward along the window 42a.

As shown in FIGS. 12A and 12B, the first coupling member 45 fixed to the tip of the output shaft 22.
Is a main body portion 45a formed in a bottomed cylindrical shape, and a main body portion 4
Engaging arms 45 as three engaging portions formed at rotationally symmetrical positions of the end of 5a and extending continuously in the axial direction and the outside.
and b. An engaging piece 45c, which is a flat surface portion capable of engaging with the facing surface of the rib 42b, is bent and formed at the tip of each engaging arm 45b.

As shown in FIGS. 13A and 13B, the second coupling member 46 fixed to the base end of the valve 10.
Is provided with a body portion 46a formed in a disc shape and having ribs formed on the peripheral edge thereof, and a plurality of engagement grooves 46b formed at rotationally symmetrical positions near the outer periphery of the body portion 46a and extending in the circumferential direction. There is. Each engaging groove 46 near the outer periphery of the main body 46a
At a position corresponding to the open end of b, a retaining hook 46c for retaining that can be engaged with the engaging arm 45b engaged with the engaging groove 46b is provided to protrude toward the valve shaft 10 side.

Then, as shown in FIG. 11, with the coil spring 29 interposed between the coupling members 45 and 46, the engagement arm 45b engages with the engagement groove 46b and prevents the slip-out. The hooking portion 46c is arranged at a position where it engages with the engaging arm 45b. Further, between the second coupling member 46 and the support plate 44, a coil spring 47 that urges the second coupling member 46 downward in FIG. 11, that is, in a direction to bring the valve body 11 closer to the valve seat 7. Is installed. In this state, both coupling members 45, 46
The spring force of the coil spring 29 holds the engaging arm 45b in contact with the main body portion 46a of the second coupling member 46. As a result, both coupling members 4 move in the direction in which the engagement arm 45b is disengaged from the engagement groove 46b.
Even if 5 and 46 try to rotate relative to each other, the retaining hook 46c is engaged with the engaging arm 45b to prevent relative rotation.

In the detent mechanism of this embodiment, the sliding portion when the output shaft 22 is linearly moved is in contact with another surface as in the second embodiment, as shown in FIG. 14B. Therefore, similarly to the above, the durability is improved and the load on the step motor 3 is reduced as compared with the first embodiment.

Further, in this embodiment, since the rib 42b as a guide portion is formed on the cover member 42 without providing the guide member 30, the number of parts and the number of assembling steps are reduced, and the manufacturing cost is reduced. . Further, since the guide member 30 does not receive a large external force after assembling, it is a thin plate press part, so that the strength is weak, and it is easily deformed by an external force when it is handled as a single item, so that it requires careful handling. However, in this embodiment, the rib 42b formed by bending a part of the cylindrical cover member 42 functions as a guide portion, so that it is robust and easy to handle. Further, the shape is simpler than that of the guide member 30, and the window 42a that is formed at the same time when the rib 42b is formed by bending functions as a window for replacing the air inside and outside the cover member 42, so that the manufacturing is easy. The cost will be lower. Further, it is only the engagement arm 45b of the first coupling member 45 that engages with the rib 42b that constitutes the rotation preventing mechanism of the output shaft 22, and the engagement arm 45b is the rotation preventing portion of the output shaft 22. Make up a part. That is, unlike both the above-described embodiments, the second coupling member 46 does not engage with the rotation stopping mechanism. Then, even if the output shaft 22 and the valve shaft 10 are misaligned, the clearance is absorbed by the clearance between the engagement groove 46b and the engagement arm 45b. Then, along with the linear movement of the output shaft 22, the valve shaft 10 is guided by the carbon bearing 8 and accurately moved in the axial direction. As a result, the valve body 11 accurately abuts the valve seat 7 from the orthogonal direction.
Therefore, in the case of this embodiment, the output shaft 22 and the valve shaft 1
Even if there is some misalignment with 0, carbon bearing 8,
Uneven wear of the valve seat and the valve body 11 is prevented, wear of the sliding portion is reduced, and the sealability between the valve body 11 and the valve seat 7 is improved.

(Fourth Embodiment) Next, a fourth embodiment will be described with reference to FIG. In this embodiment, both coupling members 2
The shapes of 5, 26 and the hook 30a are slightly different from those of the first embodiment, and the other structures are the same. That is, on each of the flanges 28a, 28b, a guide piece 48a extending obliquely toward the gap δ on the side opposite to the notch 27a,
48b are integrally formed. Also, the hook 3
The tip of 0a is not tapered but is formed flat. When assembling the coupling members 25 and 26 of this embodiment, FIG.
5 (a) and 5 (b), the coupling members 25 and 26 move downward in FIG. 15 (b) and the latching claw 30a moves upward from the temporarily assembled state where the flanges 28a and 28b are slightly overlapped. Move relatively to face. Then, the guide piece 4
8a and 48b are pushed by the hooks 30a, so that the flanges 28a,
The gap δ of 28b is expanded, and the flat surface portion 30c is formed on each flange 2
It is arranged so as to engage with the edges of 8a and 28b. That is, even with the configuration of this embodiment, the rotation stopping mechanism can be easily assembled as in the first embodiment.

As shown in FIG. 16A, the latch claw 30a
The tip of each of the flanges 28a,
When the guide pieces 48a and 48b are formed on 28b, the assembling of the rotation stopping mechanism becomes easier. Also, FIG.
As shown in (b), the positions corresponding to the end edges of the flanges 28a, 28b are bent downward to form flat surface portions 49a, 49b that engage with the flat surface portion 30c, and guide pieces 48a, 48b are formed continuously therefrom. You may form. In this case, the sliding resistance of the detent portion when the output shaft 22 moves linearly becomes small.

(Fifth Embodiment) Next, a modification of the cover member will be described with reference to FIG. The cover member 50 is formed in a substantially cylindrical shape, and the windows 50a are formed at three rotationally symmetrical positions.
Are formed. The cover member 50 is formed with a protrusion 51 forming a guide portion of the rotation stopping mechanism that is bent at a position shifted by approximately 60 ° from the window 50a so as to protrude inward over the entire length of the cover member 50. Protrusion 51
Are formed by pressing the cover member 50.

When the cover member 50 is used in the motor driven valve 1 of the second embodiment in place of the guide member 30, as shown in FIG. 18, the engaging pieces 40a, 40b.
Engages with both side surfaces of the protrusion 51 and slides in a surface contact state. Therefore, even when the cover member 50 of this embodiment is provided, the frictional resistance can be reduced and the structure of the guide portion of the rotation stopping mechanism can be simplified.

The present invention is not limited to the above embodiments, but may be embodied as follows. (1) In the third embodiment, as shown in FIG. 19A, the shape of the engaging piece 45c bent and engaged with the tip of the engaging arm 45b is engaged with the outer surface of the rib 42b of the cover member 42. It may have a possible shape. Further, the guide member 30 of the first embodiment may be used as the rotation preventing member of the coupling mechanism that employs the coupling members 45 and 46 of the third embodiment.
Then, as shown in FIG. 19B, the engaging arm 45b
The shape of the engaging piece 45c bent and formed at the tip may be a shape that holds both flat surface portions 30c from the outer surface thereof. Also in these cases, the frictional resistance when the first coupling member 45 moves together with the output shaft 22 becomes small, and the load on the step motor 3 becomes small.

(2) When a coupling member having a plurality of flanges 28a and 28b is used as in the first and second embodiments, the guide portion for preventing rotation is constituted by the cylindrical guide rod 52, and the output It may be fixed to the support plate 9 or the support member 32 so as to extend parallel to the shaft 22. Then, an engaging hole 53 as an engaging portion into which the guide rod 52 is inserted may be formed in a portion where the flanges 28a and 28b overlap each other. Also in this case, since the position of the engaging portion is far from the center of the output shaft 22, the same effect as that of the first embodiment is exhibited. Moreover, the structure of the guide portion is extremely simple.

(3) While omitting the connecting mechanism 24,
The output shaft 22 is extended to be integrated with the valve shaft 10. As a rotation stopping mechanism, as shown in FIG.
A disk-shaped flange 54 is concentrically attached to the
The engaging portion 54a is formed on the peripheral edge of the No. 4 substrate. The engaging portion 54a is composed of a pair of engaging pieces that are bent and engaged. Then, the output shaft 22 is engaged with the engaging portion 54a by engaging the engaging portion 54a.
A guide portion 55 for guiding in the axial direction is provided. Guide part 5
Reference numeral 5 denotes the hook 30a and the cover member 4 of the above embodiment.
The ribs 42a formed on the cover 2 and the protrusions 51 formed on the cover member 50 are appropriately used. Also in this case, the engaging portion 54
Since the position of a is far from the center of the output shaft 22,
The rotational force of the rotor 20 can be efficiently converted into the thrust of the output shaft 22 and the durability is improved. Further, since there is no connecting mechanism, the structure is simpler, and the number of steps and costs for forming and assembling the connecting mechanism 24 are reduced.

(4) As shown in FIG. 21B, an engaging piece 57 as an engaging portion engaged with a material different from that of the flange 56 is fixed to the outer peripheral surface of the disk-shaped flange 56. Good.
As a material of the engagement piece 57, a material having good lubricity (for example,
Materials with excellent wear resistance such as oil-impregnated sintered bearings) and materials with low frictional resistance are preferred. In this case, the cost is reduced by using only the part that is easily worn as a material having excellent wear resistance, compared with the case where the entire material is made of wear resistance.

(5) Even when the connecting mechanism is provided, the connecting mechanism is provided with only the connecting function of the output shaft 22 and the valve shaft 10, and the detent mechanism having the structure shown in FIGS. You may equip things.

(6) Various surface treatments such as chromium plating, nitriding treatment, carburizing treatment, and titanium nitride treatment may be performed in order to enhance the wear resistance of the engaging portion and the guide portion of the rotation preventing mechanism.

(7) Coupling members 25, 26, 3
The number of the flanges 28a, 28b of 8, 39, the engaging arms 45b of the coupling members 45, 46, and the engaging grooves 46b are three.
The number is not limited to one, and may be one, two, or four or more. Also in this case, the same effect as that of each of the above-described embodiments is exhibited.

(8) A flat portion 30c is not formed on the hook 30a of the guide member 30, and both sides of the hook 30a and the guide portion are configured to slide in an engaged state, or are engaged. The engaging piece 45c may not be formed at the end of the arm 45b, and both sides of the engaging arm 45b may be engaged with the ribs 42b of the cover member 42. Also, the cover members 13, 37, 42
The shape of the inner cover 17 is not cylindrical, but triangular, square,
It may be a rectangular tube such as a pentagon or hexagon.

(9) It may be applied to valves other than the EGR valve. (10) Instead of the coil spring 29 as a biasing member, a leaf spring, a bamboo shoot spring, or an elastic body such as rubber may be used. Even in this case, the same effect is exhibited. When using an elastic body such as rubber, use it under the condition that the temperature does not rise.

Inventions other than those described in the claims that can be grasped from the respective embodiments and modifications will be described below together with their effects. (1) In the invention according to claim 10, a groove extending in the radial direction and communicating with the outside is formed on the upper surface of the support member. In this case, it is easy to discharge moisture and dew condensation water that have entered the inside of the cover member of the coupling mechanism to the outside.

(2) In the invention described in claim 1, the detent member is a disk fixed concentrically to the output shaft,
The engaging portion is formed on the peripheral portion thereof. In this case, the manufacturing is simple and the cost is low.

(3) In the invention described in claim 8, both coupling members are formed into a rotationally symmetrical shape by sheet metal working. In this case, the manufacturing is simple and the cost is low, and the biasing means can be supported in a stable state.

[0076]

As described in detail above, the first to the first aspects of the invention are described.
According to the invention described in 0, the output shaft can be prevented from rotating at a position sufficiently larger than the diameter of the output shaft, friction loss in the rotation preventing portion can be reduced, and the rotational force of the rotor can be efficiently output. Can be the thrust of. Further, even if the clearance between the engaging portion and the guide portion is the same, it is possible to control the opening / closing of the valve with a small hysteresis.

According to the second aspect of the present invention, since the engaging portion and the guide portion are arranged at rotationally symmetrical positions, uneven wear of the engaging portion and the guide portion is suppressed. According to the third aspect of the invention, the rotation preventing member and the guide portion can be manufactured at low cost, and the sliding resistance is reduced.

According to the inventions of claims 4 to 6, the structure is simple and the strength is high, the number of parts and the number of assembling steps are small, the manufacturing cost is reduced, and the handling is easy. According to the invention described in claims 7 and 8, the assembling becomes easy. Further, claim 9 and claim 10
In the invention described in (3), the number of parts is reduced and the assembling is easy.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a first embodiment embodying the present invention.

2A is a perspective view of a cover member, and FIG. 2B is a front view of a state in which a coupling member is connected.

FIG. 3 is a perspective view of a coupling member.

FIG. 4 is a perspective view of a guide member.

FIG. 5 is a schematic view showing a positional relationship between a flange and a hook when connecting coupling members.

FIG. 6 is a partially cutaway front view of the second embodiment.

FIG. 7 is a plan view of the coupling member in the same connected state.

8A is a plan view of a support member to which a guide member is fixed, and FIG. 8B is a partial cross-sectional view of a crimped portion.

FIG. 9 also shows a first coupling member, (a)
Is a view as seen from the direction of arrow A in (b), and (b) is a sectional view taken along line IX-IX in (a).

FIG. 10 also shows a second coupling member,
(A) is a B arrow view of (b), (b) is the XX sectional view taken on the line of (a).

FIG. 11 is a partially cutaway front view of the third embodiment.

FIG. 12 also shows a first coupling member,
(A) is a view from the arrow C of (b), (b) is XII-XI of (a).
It is a sectional view taken along line I.

FIG. 13 also shows a second coupling member,
(A) is a view on arrow D of (b), (b) is XIII-XI of (a).
It is a II sectional view.

FIG. 14A is a schematic perspective view of a cover member, and FIG. 14B is a partial schematic perspective view showing an engagement state of an engagement arm and a cover member.

15A is a schematic plan view showing the relationship between the coupling member and the latching claw of the fourth embodiment, and FIG. 15B is a partially omitted front view thereof.

FIG. 16A is a partially omitted front view showing a modification example of the latch claw, and FIG. 16B is a partially omitted front view showing another modification example.

FIG. 17 is a schematic perspective view showing a cover member of the fifth embodiment.

FIG. 18 is a schematic perspective view showing the same operation.

FIG. 19 is a partial schematic perspective view showing the relationship between the engagement arm and the guide portion of a modified example.

FIG. 20 is a schematic plan view showing a relationship between a flange and a guide rod according to another modification.

FIG. 21 is a schematic perspective view showing a relationship between a rotation preventing member and a guide portion according to another modification.

22A is a partially cutaway front view of a conventional example, and FIG. 22B is a cross-sectional view showing a relationship between an output shaft and a bearing.

FIG. 23 is a cross-sectional view showing another conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Motor drive type valve, 2 ... Valve part, 3 ... Step motor, 5 ... Valve housing, 7 ... Valve seat, 10 ... Valve shaft, 11 ... Valve body, 18 ... Bearing, 20 ... Rotor (rotor), 21 ... Rotating body, 21a ... Female screw, 22 ... Output shaft,
22a ... Male screw, 24 ... Connection mechanism, 25, 38, 45 ...
A first coupling member that constitutes a rotation stopping member, 2
6, 39, 46 ... Second coupling member, 29 ... Coil spring as biasing member, 30 ... Guide member, 30a ...
Hooking claws as guide parts, 30b ... Supporting pieces as pressing washers, 30c ... Planar part, 32 ... Supporting members, 34 ... Packing, 37, 42 ... Cover members, 40a, 40b ... Engaging pieces as engaging parts , 42b ... Ribs as guide portions,
45b ... Engaging arm as engaging part, 45c ... Engaging piece as flat part, 52 ... Guide rod as guide part,
δ: A gap as an engaging portion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Yuzuru Ikeda, 2-chome, Toyota-cho, Kariya city, Aichi Stock company, Toyota Industries Corporation (72) Inventor, Shinichi Kusakabe, 2-chome, Toyota-cho, Kariya-shi, Aichi Stock company Toyota Automatic Loom Works

Claims (10)

[Claims] 1. A valve body having a valve body axially reciprocating in a valve housing, and a male screw threadedly engaged with a female screw provided at the center of the rotor, and a linear movement by a rotation stopping mechanism. A motor-driven valve having an output shaft for driving the valve body, wherein a bearing that supports the output shaft is provided on a side of the step motor that faces the valve housing, and a valve is provided from the bearing of the output shaft. While fixing the detent member to the housing side, the detent member is provided with at least one engaging portion at a position where the radial distance from the center of the output shaft is larger than the maximum value to the outer peripheral surface of the output shaft itself. The valve housing is configured to extend along the axial direction of the output shaft with a guide portion that engages with the engaging portion to restrict the rotation of the output shaft and allows the output shaft to move in the axial direction. The output shaft of the detent mechanism of the grayed-side or motor-driven valve provided on the motor housing side. 2. The rotation preventing mechanism for an output shaft of a motor driven valve according to claim 1, wherein a plurality of the engaging parts and the guide parts are provided at rotationally symmetrical positions about the output shaft. 3. The anti-rotation member and the guide portion are formed by press working parts, and at least one of the anti-rotation member and the guide portion is formed by a bent flat surface portion forming a sliding portion. The rotation stopping mechanism for the output shaft of the motor-driven valve according to claim 2. 4. The rotation preventing mechanism for an output shaft of a motor-driven valve according to claim 3, wherein the guide portion is integrally formed with a tubular cover member that covers a portion of the output shaft protruding from the bearing. 5. The rotation preventing mechanism for an output shaft of a motor-driven valve according to claim 4, wherein the guide portion is bent and formed so as to project inward over the entire length of the cover member. 6. The rotation preventing mechanism for an output shaft of a motor-driven valve according to claim 4, wherein the guide portion is a rib bent inward along a window formed in a peripheral wall of the cover member. 7. The output shaft is connected to a valve shaft having a valve body axially reciprocally moved in a valve housing via a connecting mechanism, and the engaging portion is formed at a predetermined position of the connecting mechanism. The detent mechanism for an output shaft of a motor-driven valve according to claim 1, wherein a guide that is thinner toward the tip side is integrally formed at the tip of the guide portion that extends along the axial direction of the output shaft. 8. The first shaft fixed to the output shaft, wherein the output shaft is connected to a valve shaft having a valve element axially reciprocated in a valve housing via a connecting mechanism.
Coupling member and the second coupling member fixed to the valve shaft are connected with part of their flanges overlapping, and the engaging portion is formed between the end portions of the flanges of both coupling members. 2. The rotation preventing mechanism for an output shaft of a motor-driven valve according to claim 1, wherein each flange is integrally formed with a guide piece that extends obliquely toward the gap. 9. The output shaft is connected to a valve shaft having a valve element axially reciprocated in the valve housing through a connecting mechanism, and a bearing for supporting the valve shaft in the valve housing is provided through a packing. The rotation stopping mechanism for an output shaft of a motor-driven valve according to claim 1, wherein the guide portion is formed integrally with a pressing washer for pressing. 10. The rotation preventing mechanism for an output shaft of a motor-driven valve according to claim 9, wherein the pressing washer is fixed to a support member that supports the bearing for the valve shaft so as to sandwich the bearing.