Link mechanism

Abstract

To provide a smooth motion of a part with simple means when two members are connected using a pin hole and a pin.SOLUTION: A link mechanism for transmitting a motion of an actuator to an external device that is operated by the actuator includes: one link member provided with a connection pin; and the other link member including a connection part in which a pin hole to which the connection pin is loosely fitted is formed. An inner diameter of an axial center part of the pin hole is smaller than an inner diameter of an opening of the pin hole.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a link mechanism. [Background technology]

[0002] Conventionally, various mechanisms for operating an external device by an actuator have been proposed (see, for example, Patent Document 1). Patent Document 1 discloses an actuator having a shaft that moves linearly in an axial direction. The linear motion of the shaft is transmitted to an external device via a connecting member. The shaft and the connecting member are connected via a joint having a pin. The joint is provided at an end of the shaft via a rotation mechanism. The rotation mechanism has a collar that is fitted onto the shaft, and two nuts that are fixed to the shaft with the collar sandwiched between them. The joint is loosely fitted onto the outer circumferential surface of the collar and is in a state of being freely rotatable around the axis of the shaft. The connecting member has a pin hole into which a pin provided in the joint is inserted. The connecting member is assembled to the joint by inserting the pin into the pin hole. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 042172 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when a pin of one member is inserted into a pin hole of the other member as a mode for connecting two members, it is considered that the machining accuracy and assembly accuracy of the members affect the operation of the connection part. In Patent Document 1, the joint connected to the connecting member is made rotatable around the axis of the shaft by the rotation mechanism. This is considered to reduce the sliding resistance between the pin hole and the pin, and to smooth the operation of the connection part. However, in the mechanism disclosed in Patent Document 1, it is necessary to prepare and attach a collar to form the rotation mechanism, which is troublesome.

[0005] Therefore, an object of the invention disclosed in this specification is to achieve smooth operation of the parts in question using simple means when two components are connected using a pin hole and a pin. [Means for solving the problem]

[0006] The above-mentioned object is achieved by a link mechanism that transmits the operation of an actuator to an external device operated by the actuator, the link mechanism including one link member provided with a connection pin and another link member having a connection portion formed with a pin hole into which the connection pin is loosely fitted, the inner diameter of the axial center of the pin hole being smaller than the inner diameter of the opening of the pin hole. Effect of the Invention

[0007] The invention disclosed in this specification makes it possible to realize smooth operation of two components connected using a pin hole and a pin using simple means. [Brief description of the drawings]

[0008] [Figure 1]Fig. 1(A) is a diagram showing a schematic configuration of an actuator and a wastegate valve connected by a link mechanism of an embodiment, showing a state in which the wastegate valve is closed, and Fig. 1(B) is a diagram showing a schematic configuration of an actuator and a wastegate valve connected by a link mechanism of an embodiment, showing a state in which the wastegate valve is open. [Diagram 2] Fig. 2(A) is a cross-sectional view taken along line A1-A1 in Fig. 1(A), and Fig. 2(B) is a perspective view of an actuator and a wastegate valve connected by a link mechanism according to an embodiment. [Diagram 3] Fig. 3(A) is an enlarged view of a first connection portion and a second connection portion of a second link member included in the link mechanism of the embodiment. Fig. 3(B) is a view of the second link member included in the link mechanism of the embodiment, seen from the second connection portion side located at one end along the longitudinal direction. Fig. 3(C) is a cross-sectional view of the second connection portion of the second link member taken along A2-A2 in Fig. 3(B). Fig. 3(D) is a schematic view showing the operation of a second connection pin inserted into a pin hole provided in the second connection portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the dimensions, ratios, etc. of each part may not be illustrated to be completely consistent with the actual ones. In addition, some details may be omitted in the drawings.

[0010] (Embodiment) 1(A) to 2(B), a link mechanism 230 of this embodiment connects an actuator 300 and a wastegate valve 201 serving as an external device. The wastegate valve 201 can be opened and closed by the operation of the actuator 300. The link mechanism 230 is a four-bar link mechanism including a first link member 231, a second link member 232, a third link member 233, and a fourth link member 234. The connection relationship of these link members will be described later.

[0011] [Actuator] The actuator 300 in this embodiment is a servo motor and includes a rotating shaft portion 301. Referring to Fig. 2(B), one end of a first link member 231 is fixed to the rotating shaft portion 301 to form a first joint portion 230A. The rotating shaft portion 301 swings the other end of the first link member 231 as indicated by an arrow 1a.

[0012] [Waistgate valve] Next, the wastegate valve 201 will be described. The wastegate valve 201 is attached to the turbine housing 110. As shown in Fig. 1(A) to Fig. 2(A), an exhaust bypass passage 111 that bypasses the turbine wheel 101 is formed in the turbine housing 110. The exhaust bypass passage 111 has a circular wastegate hole 111a that penetrates a wall body 110b of the turbine housing 110. The wastegate hole 111a communicates with the upstream side of the turbine wheel 101, i.e., the upstream side of the exhaust gas flow, and the exhaust gas outlet passage 110a. A valve seat 112 is provided on the peripheral portion of the wastegate hole 111a on the exhaust gas outlet passage 110a side.

[0013] The wastegate valve 201 includes a circular valve element 211 that opens and closes the exhaust bypass passage 111 by being seated on and released from a valve seat 112 provided in the turbine housing 110. The valve element 211 is fixed to a fourth link member 234 and attached to a swing arm 235 that operates integrally with the fourth link member 234. The valve element 211 can move between a valve closed position shown in Fig. 1(A) and a valve open position shown in Fig. 1(B) by the swing of the swing arm 235.

[0014] The valve body 211 is attached by a support pin 214 extending in a direction perpendicular to the swing arm 235. The valve body 211 is provided at the tip of the swing arm 235 so as to be slidable along the axial direction of the support pin 214. That is, the valve body 211 is attached to the tip of the swing arm 235 so as to be movable toward and away from the swing arm 235 in the valve opening and closing direction. A disc spring 213 is sandwiched between the valve body 211 and the tip of the swing arm 235. Movement of the valve body 211 in a direction away from the swing arm 235 is restricted by a stopper 215. When no pressing force is applied to the valve body 211 toward the swing arm 235, the valve body 211 abuts against the stopper 215 while being pressed toward the stopper 215 by the force of the disc spring 213. In this embodiment, the disc spring 213 is used, but other types of spring members or elastic members may be used instead of the disc spring 213. The stopper 215 may be, for example, a washer or a nut.

[0015] [Link mechanism] Referring to FIG. 2B, the link mechanism 230 includes a first joint portion 230A, a second joint portion 230B, a third joint portion 230C, and a fourth joint portion 230D.

[0016] The first joint portion 230A is a connection portion between the rotating shaft portion 301 and the first link member 231. The first link member 231 is fixed to the rotating shaft portion 301.

[0017] The second joint portion 230B is a connection portion between the first link member 231 and the second link member 232. The first link member 231 has a first connection pin 236 at an end opposite to the end fixed to the rotating shaft portion 301. The first connection pin 236 is fixed to the first link member 231. The second link member 232 has a first connection portion 232a at one end in the longitudinal direction and a second connection portion 232b at the other end. The first connection portion 232a and the second connection portion 232b each have a pin hole 250. In the second joint portion 230B, the first connection pin 236 is loosely fitted into the pin hole 250 provided in the first connection portion 232a. A washer 238 is attached to the first connection pin 236 inserted into the pin hole 250 to prevent the second link member 232 from falling off. The second joint part 230B forms a revolute pair with the first connection pin 236 and a pin hole 250.

[0018] The third joint portion 230C is a connection portion between the second link member 232 and the third link member 233. The third link member 233 has a second connection pin 237 at one end. The second connection pin 237 is fixed to the third link member 233. In the third joint portion 230C, the second connection pin 237 is loosely fitted into a pin hole 250 provided in the second connection portion 232b formed in the second link member 232. A washer 238 is attached to the second connection pin 237 inserted into the pin hole 250 so that the second link member 232 does not fall off. In the third joint portion 230C, a revolute pair is formed by the second connection pin 237 and the pin hole 250.

[0019] The fourth joint portion 230D is a connection portion between the third link member 233 and the fourth link member 234. The fourth link member 234 is fixed to an end portion of the third link member 233 opposite to the end portion where the second connection pin 237 is provided. The fourth link member 234 penetrates the wall body 110b of the turbine housing 110, and is rotatably supported by the wall body 110b of the turbine housing 110. As described above, the swing arm 235 is attached to the fourth link member 234. The swing arm 235 swings as indicated by the arrow 1b when the first link member 231 swings as indicated by the arrow 1a.

[0020] The link mechanism 230 transmits the operation of the actuator 300 to the wastegate valve 201, and opens and closes the valve body 211 of the wastegate valve 201.

[0021] Here, the first connecting portion 232a and the second connecting portion 232b of the second link member 232 will be described in detail with reference to Fig. 3(A) to Fig. 3(D). With reference to Fig. 3(A), the first connecting portion 232a and the second connecting portion 232b each have a pin hole 250. The pin hole 250 will be described below. The pin hole 250 provided in the first connecting portion 232a and the pin hole 250 provided in the second connecting portion 232b have the same configuration. Therefore, in the following description, the pin hole 250 provided in the second connecting portion 232b will be described as a representative.

[0022] As shown in FIG. 3(C), the pin hole 250 has an inner diameter Ri at the central portion 250a (see FIG. 2(B)) in the direction of the axis AX, and an inner diameter Ro at both openings 250b. Referring to FIG. 3(C), the inner diameter Ri of the central portion 250a is smaller than the inner diameter Ro of the openings 250b. As a result, a shape in which convex curved surfaces face each other appears on the A2-A2 cross section shown in FIG. 3(C). Such an R shape can be formed by chamfering the openings 250b.

[0023] As shown in FIG. 3(D), the second connection pin 237 is inserted into the chamfered pin hole 250. When the link mechanism 230 operates, it is assumed that the second connection pin 237 swings relative to the pin hole 250 as shown by the arrow 1c. The swinging second connection pin 237 comes into contact, for example, at a location indicated by reference symbol Y in FIG. 3(D). At this time, the second connection pin 237 and the pin hole 250 are in line contact or surface contact, and the surface pressure between the two when they come into contact can be reduced. As a result, smooth operation can be achieved in the second connection portion 232b. The shape of the convex curved surface can be appropriately determined so as to reduce the surface pressure between the two, taking into consideration the expected angle deviation of the second connection pin 237 relative to the pin hole 250.

[0024] In this embodiment, the external device operated by the actuator 300 via the link mechanism 230 is the wastegate valve 201. The link mechanism 230 operates in a high-temperature environment. For this reason, it is expected that the influence of the machining accuracy and assembly accuracy of the parts constituting the link mechanism 230 will be large. However, in this embodiment, by adopting the pin hole 250 in which the inner diameter Ri of the central portion 250a is smaller than the inner diameter Ro of the opening portion 250b, it is possible to realize smooth operation of the first connecting portion 232a and the second connecting portion 232b.

[0025] [effect] According to this embodiment, by the simple means of making the inner diameter of the axial center of the pin hole into which the connection pin is inserted smaller than the inner diameter of the opening of the pin hole, smooth operation of the pin hole can be achieved. This embodiment can achieve smooth operation of the link mechanism without the need for the effort of preparing and incorporating additional parts into the link mechanism.

[0026] In this embodiment, a four-bar link is used as the link mechanism, but the form of the link mechanism is not limited to this, and any form may be used as long as it is a mechanism having joints using pin holes and pins. Furthermore, the external device is not limited to a wastegate valve, and the link mechanism of this embodiment can be applied to any device that can be driven by an actuator via a link mechanism.

[0027] The above-described embodiments are merely examples for implementing the present invention, and the present invention is not limited to these. Various modifications of these embodiments are within the scope of the present invention. Furthermore, it is self-evident from the above description that various other embodiments are possible within the scope of the present invention. [Explanation of symbols]

[0028] 101 turbine wheel, 110 turbine housing, 112 valve seat, 201 wastegate valve, 211 valve body, 230 link mechanism, 230A first joint portion, 230B second joint portion, 230C third joint portion, 230D fourth joint portion, 231 first link member, 232 second link member, 232a first connection portion, 232b second connection portion, 233 third link member, 234 fourth link member, 235 swing arm, 236 first connection pin, 237 second connection pin, 250 pin hole, 250a central portion, 250b opening, 300 actuator, 301 rotating shaft portion

Claims

[Claim 1] A link mechanism that transmits an operation of an actuator to an external device operated by the actuator, A link member provided with a connection pin; another link member having a connection portion in which a pin hole into which the connection pin is loosely fitted is formed, The inner diameter of the pin hole at the axial center is smaller than the inner diameter of the opening of the pin hole. Link mechanism.

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