Butterfly exhaust throttle device

Abstract

A butterfly exhaust throttle device (1) comprises an electric actuator (42), a throttle body (21), a throttle valve shaft (23), and a four-bar link mechanism (3) that connects an output shaft (41) of the electric actuator (42) and the throttle valve shaft (23). The four-bar link mechanism (3) includes a driver (34), a follower (31), and an intermediate link (33). In the intermediate link (33), the bearing press-fit position of a rotational pair on the driver side and the bearing press-fit position of a rotational pair on the follower side are arranged at different positions relative to the axial direction of a bearing, and are inclined relative to a direction perpendicular to the axial direction of the bearing.

Description

Butterfly type exhaust throttle device

[0001] The present disclosure relates to a butterfly-type exhaust throttling device.

[0002] A butterfly-type exhaust throttle device is a device that uses driving force generated by an electric actuator to open and close a throttle valve that controls the exhaust flow rate of an internal combustion engine. For example, Patent Document 1 describes a throttle device that can be made smaller and lighter. The throttle device described in Patent Document 1 has an installation space for a reduction gear mechanism that transmits power from a motor to a throttle valve shaft, and a frame for attaching a gear cover that is formed to surround the installation space for the reduction gear mechanism, formed on one side of the side wall of the throttle body. Furthermore, the height of the frame is made lower so that it is lower than the installation height of a gear attached to one end of the throttle valve shaft, and a gear cover that covers the installation space for the reduction gear mechanism is attached to the frame.

[0003] Patent No. 3992928

[0004] The conventional technology described in Patent Document 1 has a problem in that heat conduction from the fluid passing through the flow passage formed in the throttle body when the internal combustion engine is operating limits the size and weight reduction of the throttle body. For example, when the internal combustion engine is operating, fluid of nearly 800°C passes through the flow passage. The temperature of the heat conducted from the high-temperature throttle body to the gear cover may exceed the melting point of synthetic resin, making it impossible to use synthetic resin as the material for the gear cover. In this case, a relatively large gear case is formed integrally with the throttle body, which increases the size and weight of the entire throttle body including the gear case.

[0005] The present disclosure is devised to solve the above-mentioned problems, and aims to provide a butterfly-type exhaust throttle device that enables the throttle body to be made smaller and lighter.

[0006] The butterfly-type exhaust throttle device according to the present disclosure is a butterfly-type exhaust throttle device for an internal combustion engine, and comprises an electric actuator that rotates an output shaft, a throttle body having a flow passage formed therein, a throttle valve shaft having a throttle valve attached thereto, and a four-bar link mechanism that connects the output shaft of the electric actuator to the throttle valve shaft, the four-bar link mechanism having a driver fitted onto the output shaft of the electric actuator, a driven link fixed to the throttle valve shaft, and an intermediate link that connects the driver and driven links and has bearings press-fitted into and fixed to the rotary pair on the driver side and the rotary pair on the driven side, respectively, and the intermediate link is inclined relative to the direction perpendicular to the axial direction of the bearing so that the bearing press-fit position of the rotary pair on the driver side and the bearing press-fit position of the rotary pair on the driven side are positioned at different positions relative to the axial direction of the bearing.

[0007] According to the present disclosure, the output shaft of an electric actuator and a throttle valve shaft are connected by a four-bar link mechanism. The four-bar link mechanism includes a driver attached to the output shaft, a driven member attached to the throttle valve shaft, and an intermediate member connecting the driver and driven members and having bearings press-fitted into both the driver-side and driven-side rotation pairs, and the intermediate member is inclined relative to a direction perpendicular to the bearing axial direction so that the bearing press-fit positions of the driver-side and driven-side rotation pairs are different from each other in the bearing axial direction. This allows the butterfly-type exhaust throttle device to have a smaller and lighter throttle body.

[0008] 1 is a block diagram showing the configuration of a butterfly-type exhaust throttle device according to a first embodiment. FIG. 2 is a perspective view showing the appearance of a throttle body. FIG. 3 is a cross-sectional arrow view showing a cross section of the throttle body taken along line A-A in FIG. 2. FIG. 4 is a top view showing the appearance of a throttle body and a four-bar linkage mechanism. FIG. 5 is a top view showing the appearance of a throttle body and a four-bar linkage mechanism having a linear intermediate link. FIG. 6 is a side view showing the appearance of an electric actuator and a driver link. FIG. 7 is a cross-sectional view showing a cross section of the output shaft, driver link, and driver link side pin of the electric actuator. FIG. 8 is a side view showing the appearance of an intermediate link. FIG. 9 is a front view showing the appearance of a butterfly-type exhaust throttle device having an intermediate link that is not inclined with respect to the axial direction of the bearing. FIG. 10 is a front view showing the appearance of a butterfly-type exhaust throttle device according to a first embodiment. FIG. 11 is a cross-sectional view showing a cross section of a rotation pair on the follower side of the intermediate link. FIG. 12 is a cross-sectional view showing a cross section of a rotation pair on the driver side of the intermediate link. FIG. 13 is a side view showing the appearance of a four-bar linkage mechanism. FIG. 14 is a cross-sectional view showing a cross section of a rotation pair on the follower side of the intermediate link and a follower. FIG. 1 is a cross-sectional view showing a cross section of a revolute pair on the driver side of the intermediate link and a driver link. FIG. 2 is a front view showing the appearance of a butterfly-type exhaust throttle device according to embodiment 1. FIG. 3 is a front view showing the appearance of a butterfly-type exhaust throttle device with a bracket attached. FIG. 4 is a rear view showing the appearance of a butterfly-type exhaust throttle device with a bracket attached. FIG. 5 is a top view showing the appearance of a four-bar link mechanism in a throttle body. FIG. 6 is a cross-sectional view showing the follower-side pin press-fitting into the revolute pair on the follower side of the intermediate link. FIG. 7 is a cross-sectional view showing the driver-side pin press-fitting into the revolute pair on the driver side of the intermediate link. FIG. 8 is a side view showing the appearance of a four-bar link mechanism of a butterfly-type exhaust throttle device according to embodiment 2. FIG. 9 is a cross-sectional view showing the follower-side pin press-fitting into the revolute pair on the follower side of the intermediate link of embodiment 2.

[0009] Embodiment 1. A butterfly-type exhaust throttle device according to embodiment 1 is a device that is mounted on an internal combustion engine of an automobile to control the flow of exhaust gas from the internal combustion engine, and uses a rotating disk-shaped throttle valve to open and close an exhaust flow path formed in a throttle body. The butterfly-type exhaust throttle device according to embodiment 1 will be described in detail below.

[0010] (Basic configuration of butterfly-type exhaust throttle device) Figure 1 is a block diagram showing the configuration of a butterfly-type exhaust throttle device 1 according to embodiment 1. As shown in Figure 1, the butterfly-type exhaust throttle device 1 comprises a throttle body 2, a four-bar linkage mechanism 3, and an actuator 4.

[0011] The throttle body section 2 is a component that includes a throttle body, a throttle valve, and a throttle valve shaft. The throttle valve shaft is connected to the actuator section 4 by a four-bar linkage. The throttle body has a flow path through which exhaust fluid passes, and a throttle valve attached to the throttle valve shaft is installed in the flow path, and the flow of fluid is adjusted by the throttle valve. The throttle valve opens and closes when rotational driving force generated by an electric actuator is transmitted to the throttle valve shaft by the four-bar linkage.

[0012] In the four-bar link mechanism 3, the driver, which is the input link attached to the output shaft of the electric actuator, which is the fixed link, performs rotational motion, and this rotational motion is transmitted to the follower, which is the output link, via the intermediate link, which is the connecting link. The fixed link is a fixed link that forms the foundation of the mechanism and is the part that serves as the reference for the overall movement. The input link is a link that receives power and performs oscillating motion. The output link is a link that moves in response to the movement of the input link and is responsible for the output of the mechanism. The connecting link is a link that connects the input link and output link and transmits the overall movement.

[0013] The actuator unit 4 is a component that includes an electric actuator. An electric actuator is a device that converts electrical energy into mechanical motion. The electric actuator includes a motor, a gearbox, an output shaft, a control unit, and a sensor. The motor converts electrical energy into rotational motion. The gearbox reduces the rotational speed of the motor and increases the torque. The output shaft is an axis that transmits the rotational motion of the motor to the outside. The control unit is an electronic circuit that controls the operation of the electric actuator, obtains sensor information from a position sensor or a speed sensor, and controls the motor based on the sensor information.

[0014] (Throttle Body) FIG. 2 is a perspective view showing the appearance of the throttle body 2. FIG. 3 is a cross-sectional arrow view showing the cross section of the throttle body 2 taken along line A-A in FIG. 2. As shown in FIGS. 2 and 3, the throttle body 2 is composed of a throttle body 21, a throttle valve 22, a throttle valve shaft 23, and a spring 24. The throttle body 21 is a cylindrical member in which an exhaust flow passage 21a is formed. A spring locking portion 21b is formed on the surface of the throttle body 21, and a full-open stopper 21c is formed at a position different from the spring locking portion 21b along the axial direction of the exhaust flow passage 21a. In addition, two threaded holes 21d are formed side by side on the surface of the throttle body 21 along the axial direction of the exhaust flow passage 21a.

[0015] The throttle valve 22 is provided in the exhaust flow passage 21a of the throttle body 21, and is fixed to a throttle valve shaft 23 by press-fitting a pin 22a. One end 23a of the throttle valve shaft 23 is a press-fit shaft end, and is press-fitted and fixed into a press-fit hole 31a formed in one end of a follower 31 that constitutes the four-bar linkage 3. A follower-side pin 32 is press-fitted and fixed into a press-fit hole formed in the other end of the follower 31.

[0016] The spring 24 is a coil spring as shown in Fig. 3, and is arranged between the throttle body 21 and the follower 31 so as to surround the portion of the throttle body 21 through which the throttle valve shaft 23 passes, with the spring 24 being compressed in the axial direction of the throttle valve shaft 23 from its natural state. Furthermore, as shown in Fig. 2, one end 24a of the spring 24 functions as a fixed end and is engaged with a spring engaging portion 21b provided on the throttle body 21. The other end 24b of the spring 24 functions as a free end and is engaged with a stopper engaging portion 31b provided on the follower 31. The spring 24 is attached to the throttle body 21 in a state twisted from its natural state, thereby urging the follower 31 and the throttle valve shaft 23 fixed thereto in the direction of opening the throttle valve 22.

[0017] Figure 4 is a top view showing the appearance of the four-bar linkage mechanism 3 having the throttle body 21 and the arc-shaped intermediate link 33. In Figure 4, the axial length of the throttle body 21 is L1. The intermediate link 33 has a node 33a connecting both end revolute pairs, which is an arc-shaped member when viewed from above. By making the node 33a arc-shaped, it is possible to prevent the node 33a from interfering with the spring 24. This makes it possible to position the end of the driving link 34 where the press-fit hole 34a is formed on the side indicated by arrow B.

[0018] 5 is a top view showing the appearance of a four-bar linkage having a throttle body 21A and a linear intermediate link 33A, illustrating a hypothetical butterfly-type exhaust throttle device 1A in which the intermediate link is linear. As shown in FIG. 5, in the linear intermediate link 33A, the end of the driving link 34 that is connected to the output shaft 41 must be positioned away from the plane indicated by arrow B in order to avoid interference between the spring 24 and the intermediate link 33A.

[0019] For this reason, when the position of screw hole 21d is fixed to the surface indicated by arrow B of throttle body 21A, the position of the other screw hole 21d must be moved away from the surface indicated by arrow B by the same amount as the position of the end of driver link 34 that is connected to output shaft 41, as described above. As a result, the axial length L2 of throttle body 21A becomes longer than L1. By making the node portion 33a of the intermediate link 33 arc-shaped, the butterfly-type exhaust throttle device 1 can make the throttle body 21 more compact and therefore lighter than a butterfly-type exhaust throttle device 1A that has a straight intermediate link 33A.

[0020] The follower 31 is connected to one rotational pair of the intermediate link 33 via a follower-side pin 32, and the driver 34 is connected to the other rotational pair of the intermediate link 33 via a driver-side pin 35. The driver-side pin 35 is fitted into the rotational pair of the intermediate link 33, and the rotational pair is rotatably connected to the end of the driver 34 by a washer 36 and a retaining ring 37.

[0021] The end 23a of the throttle valve shaft 23 is press-fitted into a press-fit hole formed in the center of the follower 31, and a stopper locking portion 31b is formed on part of the outer shape of the follower 31, as shown in Figure 4. A full-open stopper 21c that determines the mechanical full-open position of the throttle valve 22 is provided on the surface of the throttle body 21. For example, when the throttle valve 22 is rotated in the opening direction to the mechanical full-open position, the stopper locking portion 31b of the follower 31 abuts against the full-open stopper 21c, preventing the throttle valve 22 from opening beyond the mechanical full-open position.

[0022] (Actuator Unit) Fig. 6 is a side view showing the appearance of the electric actuator 42 and the driver 34. Fig. 7 is a cross-sectional view showing the output shaft 41, driver 34, and driver side pin 35 of the electric actuator 42, taken along the axial direction of the output shaft 41. As shown in Figs. 6 and 7, the actuator unit 4 is configured to include the output shaft 41 and the electric actuator 42. The output shaft 41 rotates due to torque generated by a motor (not shown) included in the electric actuator 42.

[0023] A press-fit portion 41a and a male thread portion 41b are formed on the end of the output shaft 41. When the press-fit portion 41a is press-fitted into the press-fit hole 34a of the driver 34, the portion protruding from the driver 34 is the male thread portion 41b, and in this state, a nut 44 is fastened to the male thread portion 41b. This prevents the output shaft 41 from coming off the driver 34. A press-fit hole 34b is formed in the other rotational pair of the driver 34, and the end of the driver pin 35 connected to the rotational pair of the intermediate link 33 is press-fitted into the press-fit hole 34b. The electric actuator 42 rotates the motor using a control signal and converts the rotational force into rotational motion of the output shaft 41. The rotational force of the output shaft 41 is converted into oscillating motion of the driver 34.

[0024] (Four-bar link mechanism) The four-bar link mechanism 3 is configured to include a follower 31, an intermediate link 33, and a driver 34. The follower 31 is connected to the throttle body 2, the driver 34 is connected to the output shaft 41 of the electric actuator 42, and the intermediate link 33 connects the follower 31 and the driver 34. The intermediate link 33 may be a member formed from synthetic resin.

[0025] Figure 8 is a side view showing the appearance of the intermediate link 33. As shown in Figure 8, a follower-side bearing 38 is press-fitted into the rotation pair on the follower side of the intermediate link 33, and a driver-side bearing 39 is press-fitted into the rotation pair on the driver side of the intermediate link 33. The follower-side pin 32 is inserted into the follower-side bearing 38 to rotatably hold the rotation pair on the follower side of the intermediate link 33, and the driver-side pin 35 is inserted into the driver-side bearing 39 to rotatably hold the rotation pair on the driver side of the intermediate link 33.

[0026] The follower-side bearing 38 and the driver-side bearing 39 may be members formed from resin or metal, which has a smaller linear expansion coefficient than the material forming the intermediate link 33. If the intermediate link 33 is a member formed from metal, the follower-side bearing 38 and the driver-side bearing 39 are formed from, for example, carbon, which has a smaller linear expansion coefficient than the metal intermediate link 33. This makes it possible to reduce the weight of the follower-side bearing 38 and the driver-side bearing 39 compared to when they are formed from metal.

[0027] Assuming that the end of the output shaft 41 of the electric actuator 42 connected to the driver 34 faces downward, there is an up-and-down relationship as shown by the double-headed arrow in Figure 8. In the four-bar linkage 3, the bearing press-fit position of the rotation pair on the driver side of the intermediate link 33 and the bearing press-fit position of the rotation pair on the driven side are located at different positions relative to the axial direction of the bearing. The intermediate link 33 is inclined relative to the direction perpendicular to the axial direction of the bearing.

[0028] For example, as shown in Figure 8, the bearing press-fit position of the rotation pair on the driver side of the intermediate link 33 may be located lower than the bearing press-fit position of the rotation pair on the follower side. A press-fit hole 33b is formed in the rotation pair on the follower side of the intermediate link 33, with the upper opening periphery of press-fit hole 33b being an upper flat surface 33c and the lower opening periphery being a lower flat surface 33d. A press-fit hole 33e is formed in the rotation pair on the driver side of the intermediate link 33, with the upper opening periphery of press-fit hole 33e being an upper flat surface 33f and the lower opening periphery being a lower flat surface 33g. In the intermediate link 33, as shown in FIG. 8, there is a height difference of a distance Δ between the upper flat surface 33c of the rotation pair on the follower side and the upper flat surface 33f of the rotation pair on the driver side, and the height difference is inclined relative to the direction perpendicular to the axial direction of the follower-side bearing 38 and the driver-side bearing 39.

[0029] Figure 9 is a front view showing the appearance of a butterfly-type exhaust throttle device 1B having an intermediate link 33B that is not inclined relative to the axial direction of the bearing, and shows a hypothetical butterfly-type exhaust throttle device that assumes an intermediate link that is not inclined relative to the axial direction of the bearing. As shown in Figure 9, in intermediate link 33B, the bearing press-fit position of the rotation pair on the driver side and the bearing press-fit position of the rotation pair on the driven side are at approximately the same position relative to the axial direction of the bearing, and there is no difference in height between the upper flat surface of the rotation pair on the driven side and the upper flat surface of the rotation pair on the driver side.

[0030] Figure 10 is a front view showing the appearance of the butterfly-type exhaust throttle device 1, and shows the butterfly-type exhaust throttle device 1 as seen from the direction of the central axis of the exhaust flow path 21a. As shown in Figure 10, when seen from the direction of the central axis of the exhaust flow path 21a of the throttle body 21, the end of the output shaft 41 of the electric actuator 42 is positioned vertically lower than the position of the end of the throttle valve shaft 23 to which the follower 31 is attached and closer to the central axis of the exhaust flow path 21a. This positional relationship is designated as P.

[0031] For example, by configuring the butterfly-type exhaust throttle device 1 according to the positional relationship P, it is possible to shorten the distance L3 from the end of the output shaft 41 to the center of the exhaust passage 21a when viewed from the central axial direction of the exhaust passage 21a of the throttle body 21. This allows the butterfly-type exhaust throttle device 1 to be made smaller and lighter. The positional relationship P can also be achieved by providing an intermediate link 33 that is inclined with respect to a direction perpendicular to the axial direction of the follower-side bearing 38 and the driver-side bearing 39. That is, as shown in FIG. 8 , it is also possible to shorten the distance L3 by providing a height difference of a distance Δ between the upper flat surface 33c of the follower-side revolute pair and the upper flat surface 33f of the driver-side revolute pair in the intermediate link 33.

[0032] If there is no difference in height between the upper flat surface of the rotational pair on the driven link side and the upper flat surface of the rotational pair on the driver link side, as in the case of the intermediate link 33B shown in Figure 9, the distance L3 shown in Figure 10 will be long. Therefore, in the butterfly-type exhaust throttle device 1B, the space occupied by the electric actuator 42 in the axial direction of the output shaft 41 becomes large, limiting miniaturization.

[0033] Figure 11 is a cross-sectional view showing a cross section of the rotation pair on the follower side of the intermediate link 33, and shows the rotation pair on the follower side of the intermediate link 33 and the follower-side bearing 38. Figure 12 is a cross-sectional view showing a cross section of the rotation pair on the driver side of the intermediate link 33, and shows the rotation pair on the driver side of the intermediate link 33 and the driver-side bearing 39. The follower-side bearing 38 and the driver-side bearing 39 are bearings that are press-fitted into the rotation pair on the intermediate link 33, and have a flange shape with a collar.

[0034] 11, the follower-side bearing 38 is made up of a flange 38a and a cylindrical portion 38b with one end integrally formed with the flange 38a. The follower-side bearing 38 is formed with a hole 38c that passes through the flange 38a and the cylindrical portion 38b, and the follower-side pin 32 is inserted into the hole 38c. The driver-side bearing 39 is made up of a flange 39a and a cylindrical portion 39b with one end integrally formed with the flange 39a. The driver-side bearing 39 is made up of a flange 39a and a cylindrical portion 39b with one end integrally formed with the flange 39a. The driver-side bearing 39 is made up of a hole 39c that passes through the flange 39a and the cylindrical portion 39b, and the driver-side pin 35 is inserted into the hole 39c.

[0035] 8 and 11, the follower-side bearing 38 is fixed by press-fitting a cylindrical portion 38b into a press-fit hole 33b provided in the rotation pair on the follower side of the intermediate link 33 so that the flat portion of the flange 38a comes into surface contact with the lower flat portion 33d of the rotation pair on the follower side of the intermediate link 33. As shown in Figures 8 and 12, the driver-side bearing 39 is fixed by press-fitting a cylindrical portion 39b into a press-fit hole 33e provided in the rotation pair on the driver side of the intermediate link 33 so that the flat portion of the flange 39a comes into surface contact with the upper flat portion 33f of the rotation pair on the driver side of the intermediate link 33.

[0036] As shown in Figure 8, the direction of the end of the output shaft 41 of the electric actuator 42 to which the driver 34 is connected is defined as downward. In this case, in a cross section including the axes of both of the two rotation pairs of the intermediate link 33, a bearing is press-fitted into the upper of the two rotation pairs of the intermediate link 33 with its flange facing downward, and a bearing is press-fitted into the lower of the two rotation pairs with its flange facing upward. For example, as shown in Figures 8 and 11, in the intermediate link 33, the cylindrical portion 38b of the follower-side bearing 38 is press-fitted into the press-fit hole 33b of the upper follower-side rotation pair with its flange 38a facing downward. As shown in Figures 8 and 12, the cylindrical portion 39b of the driver-side bearing 39 is press-fitted into the press-fit hole 33e of the lower driver-side rotation pair with its flange 39a facing upward.

[0037] (Connection between the throttle body, four-bar link mechanism, and actuator) Figure 13 is a side view showing the appearance of the four-bar link mechanism 3. As shown in Figure 13, in the four-bar link mechanism 3, the follower 31 is connected to one revolute pair of the intermediate link 33 via a follower-side pin 32, and the driver 34 is connected to the other revolute pair of the intermediate link 33 via a driver-side pin 35. The follower-side pin 32 is inserted into a follower-side bearing 38 press-fitted into the revolute pair on the follower side of the intermediate link 33, and is retained by a washer 36 and a retaining ring 37. Similarly, the driver-side pin 35 is inserted into a driver-side bearing 39 press-fitted into the revolute pair on the driver side of the intermediate link 33, and is retained by a washer 36 and a retaining ring 37. The rotation of the follower 31 is stopped by a stopper locking portion 31b of the throttle body 21.

[0038] 14 is a cross-sectional view showing the follower-side rotation pair of the intermediate link 33 and the follower 31. As shown in FIG. 14 , in the intermediate link 33, a follower-side bearing 38 is press-fitted into a press-fit hole 33b of the follower-side rotation pair. One end of the follower-side pin 32 inserted into the follower-side bearing 38 is press-fitted into a press-fit hole 31c formed in the follower 31. A groove is formed on the outer periphery of the other end of the follower-side pin 32. A washer 36 is passed through the other end of the follower-side pin 32 exposed from the follower-side bearing 38, and a retaining ring 37 is fitted into the groove. This prevents the follower-side pin 32 from coming off the follower-side bearing 38. The flange of the follower-side bearing 38 is attached so as to abut against the side opposite the follower 31, i.e., the lower side, via the follower-side rotation pair.

[0039] 15 is a cross-sectional view showing the driver-side rotation pair of the intermediate link 33 and the driver 34. As shown in FIG. 15 , a driver-side bearing 39 is press-fitted into the press-fit hole 33e of the driver-side rotation pair of the intermediate link 33. One end of the driver-side pin 35 inserted into the driver-side bearing 39 is press-fitted into the driver 34. A groove is formed on the outer periphery of the other end of the driver-side pin 35. A washer 36 is passed through the other end of the driver-side pin 35 exposed from the driver-side bearing 39, and a retaining ring 37 is fitted into the groove. This prevents the driver-side pin 35 from coming off the driver-side bearing 39. The flange of the driver-side bearing 39 is attached so as to abut against the opposite side of the driver 34, i.e., the upper side, via the driver-side rotation pair.

[0040] As described above, the follower-side pin 32 press-fitted into the follower 31 is inserted into the follower-side bearing 38 of the intermediate link 33, and the driver-side pin 35 press-fitted into the driver-side pin 34 is inserted into the driver-side bearing 39 press-fitted into the driver-side press-fit hole in the intermediate link 33, thereby connecting the throttle body 2 and the four-bar linkage 3. In this way, the power generated by the electric actuator 42 is transmitted to the throttle valve shaft 23 via the output shaft 41, driver 34, intermediate link 33 and follower 31.

[0041] Furthermore, in the butterfly-type exhaust throttle device 1, the throttle body section 2 and the actuator section 4 are connected via a four-bar link mechanism 3. This makes it possible to lengthen the heat transfer path from the exhaust flow path 21a, through which high-temperature exhaust gas from the throttle body 21 flows, to the actuator section 4, reducing the amount of heat transferred from the high-temperature exhaust gas to the electric actuator 42. This allows the electric actuator 42 to be made of a generally lightweight, low-heat-resistant material, making it possible to reduce the weight of the butterfly-type exhaust throttle device 1.

[0042] (Bracket) A bracket is attached to the electric actuator. The position of the electric actuator relative to the throttle body is fixed by the bracket. Figure 16 is a front view showing the appearance of the butterfly-type exhaust throttle device 1, showing the butterfly-type exhaust throttle device 1 as seen from the direction of the central axis of the exhaust flow path 21a. As shown in Figure 16, a threaded hole 21d is formed in the surface of the throttle body 21, aligned with the central axis of the exhaust flow path 21a, and further, two threaded holes 42a are formed side by side in the surface of the electric actuator 42 as seen from the direction of the central axis of the exhaust flow path 21a.

[0043] Figure 17 is a front view showing the appearance of the butterfly-type exhaust throttle device 1 with the bracket 5 attached, and shows the butterfly-type exhaust throttle device 1 as seen from one side in the direction of the central axis of the exhaust flow path 21a. Figure 18 is a rear view showing the appearance of the butterfly-type exhaust throttle device 1 with the bracket 5 attached, and shows the butterfly-type exhaust throttle device 1 as seen from the other side in the direction of the central axis of the exhaust flow path 21a. As shown in Figures 17 and 18, the bracket 5 has two plate-shaped members.

[0044] One of the plate-shaped members of the bracket 5 has three through holes formed therein, corresponding to the screw hole 21d of the throttle body 21 and the two screw holes 42a of the electric actuator 42. As shown in FIG. 17 , one of the plate-shaped members of the bracket 5 is fixed to the screw hole 21d and the two screw holes 42a by screws 5a passed through each of the three through holes. Similarly, the other plate-shaped member of the bracket 5 has three through holes formed therein, corresponding to the screw hole 21d of the throttle body 21 and the two screw holes 42a of the electric actuator 42. As shown in FIG. 18 , the other plate-shaped member of the bracket 5 is fixed to the screw hole 21d and the two screw holes 42a by screws 5a passed through each of the three through holes. This fixes the position of the electric actuator 42 relative to the throttle body 21 via the bracket 5.

[0045] In the exhaust passage 21a of the throttle body 21, the flow rate of fluid flowing in the direction of arrow B shown in Figure 4 is adjusted according to the opening degree of a disk-shaped throttle valve 22 disposed inside the exhaust passage 21a. When the internal combustion engine is in the key-off state, as shown in Figure 4, the stopper engaging portion 31b is pushed back to a position where it abuts against the full-open stopper 21c by the returning force of the spring 24 in the opening direction.

[0046] (Operation of butterfly-type exhaust throttle device) Figure 19 is a top view showing the appearance of the four-bar link mechanism 3 in the throttle body 21. From a state in which the stopper engaging portion 31b formed on the follower 31 abuts against the full-open stopper 21c provided on the surface of the throttle body 21, the throttle valve shaft 23 is driven to rotate in the closing direction of the throttle valve 22. At this time, the follower 31 swings to a position where the rotational torque of the output shaft 41 by the electric actuator 42 and the return force of the spring 24 in the opening direction are balanced.

[0047] When the rotational torque of the output shaft 41 of the electric actuator 42 and the return force of the spring 24 in the opening direction are balanced, the intermediate link 33 is in a statically balanced state. In the intermediate link 33, there is an axial height difference between the follower-side bearing 38 and the driver-side bearing 39. As a result, a tensile load F1 is applied to the intermediate link 33. The tensile load F1 can be resolved into an axial component of the bearing and a radial component of the bearing, F2. As a result, the radial component of the tensile load F1 is applied via the follower-side pin 32 and the driver-side pin 35 on the same straight line connecting the central axes of the follower-side bearing 38 and the driver-side bearing 39, as shown by the dashed line in FIG. 19 .

[0048] (Action of Force at the Rotation Pair on the Follower Side of the Intermediate Link) Figure 20 is a cross-sectional view showing the follower-side pin being press-fitted into the rotation pair on the follower side of the intermediate link 33. As shown in Figure 20, one end of the follower-side pin 32 is press-fitted into the press-fit hole 31c of the follower 31, and the other end is inserted into the follower-side bearing 38. The cylindrical portion 38b of the follower-side bearing 38 is press-fitted into the rotation pair on the follower side of the intermediate link 33, with the flange portion 38a facing downward. The end of the follower-side pin 32 inserted into the follower-side bearing 38 is prevented from coming out by a washer 36 and a retaining ring 37.

[0049] 20, the radial component force F2 causes the inner periphery of the press-fit hole 33b of the follower-side rotation pair in the intermediate link 33 to come into contact with the outer periphery 38d of the cylindrical portion 38b of the follower-side bearing 38, and also causes the outer periphery 32a of the follower-side pin 32 to come into contact with the inner periphery 38e of the cylindrical portion 38b of the follower-side bearing 38. If the coefficient of friction between the follower-side bearing 38 and the follower-side press-fit hole 33b is μ1, then the frictional force μ1·F2 generated between the follower-side bearing 38 and the follower-side press-fit hole 31c is generated in the downward direction, which is opposite to the axial component force.

[0050] Let M be the mass of the follower-side bearing 38 and g be the gravitational acceleration. When gravity M·g acts on the follower-side bearing 38 in a downward direction, the coefficient of friction between the follower-side bearing 38 and the follower-side pin 32 is μ2. In this case, a frictional force μ2·F2 acting between the follower-side bearing 38 and the follower-side pin 32 acts in an upward direction, opposite to the frictional force μ1·F2. The acceleration α acting in the axial direction of the follower-side bearing 38 is α=μ2·F2 / M-μ1·F2 / M-g. In this case, if the resultant force of gravity on the follower-side bearing 38 and the frictional force acting between the follower-side bearing 38 and the follower-side press-fit hole 33b is smaller than the frictional force acting between the follower-side bearing 38 and the follower-side pin 32, then the acceleration α acts in an upward direction, as shown by the arrow in FIG. 20 . As a result, the follower-side bearing 38 moves in a direction in which the flat surface 38f of the flange 38a comes into contact with the lower flat surface 33d.

[0051] The frictional force μ1·F2 generated between the follower-side bearing 38 and the follower-side press-fit hole 33b changes from an interference fit to a clearance fit, for example, in a high-temperature environment due to a difference in linear expansion coefficient caused by a difference in the materials of the follower-side bearing 38 and the intermediate link 33. Even in this case, the radial component force F2 of the tensile load F1 presses the follower-side pin 32 against the follower-side press-fit hole 33b, generating frictional forces μ1·F2.

[0052] As the flat surface of the flange 38a of the follower-side bearing 38 moves in the direction of contact with the lower flat surface 33d, the relative velocity of the flat surface 38f of the flange 38a of the follower-side bearing 38 with respect to the lower flat surface 33d of the rotation pair on the follower side of the intermediate link 33 becomes 0. It is possible to maintain the position of the flat surface 38f of the flange 38a of the follower-side bearing 38 with respect to the lower flat surface 33d of the rotation pair on the follower side of the intermediate link 33.

[0053] (Action of Force at the Rotational Pair on the Driver Side of the Intermediate Link) Figure 21 is a cross-sectional view showing the driver pin being press-fitted into the rotational pair on the driver side of the intermediate link 33. As shown in Figure 21, one end of the driver pin 35 is press-fitted into the press-fit hole 34b of the driver 34, and the other end is inserted into the driver bearing 39. The cylindrical portion 39b of the driver bearing 39 is press-fitted into the rotational pair on the driver side of the intermediate link 33, with the flange 39a facing upward. The end of the driver pin 35 inserted into the driver bearing 39 is prevented from coming out by a washer 36 and a retaining ring 37.

[0054] 21, the radial component force F2 causes the inner periphery of the press-fit hole 33e of the rotation pair on the driver side of the intermediate link 33 to come into contact with the outer periphery 39d of the cylindrical portion 39b of the driver side bearing 39, and also causes the outer periphery 35a of the driver side pin 35 to come into contact with the inner periphery 39e of the cylindrical portion 39b of the driver side bearing 39. If the coefficient of friction between the driver side bearing 39 and the driver side press-fit hole 33e is μ1, then a frictional force μ1·F2 generated between the driver side bearing 39 and the driver side press-fit hole 33b occurs in the upward direction, which is opposite to the axial component force.

[0055] The mass of the driver-side bearing 39 is M, and the gravitational acceleration is g. Gravity M·g acts on the driver-side bearing 39 in a downward direction. The coefficient of friction between the driver-side bearing 39 and the driver-side pin 35 is μ2. In this case, a friction force μ2·F2 acting between the driver-side bearing 39 and the driver-side pin 35 acts upward, in the opposite direction to the friction force μ1·F2. The acceleration α acting in the axial direction of the driver-side bearing 39 is α = -μ2·F2 / M + μ1·F2 / M-g. In this case, if the resultant force of the gravity of the driver-side bearing 39 and the friction force acting between the driver-side bearing 39 and the driver-side press-fit hole 33b is smaller than the friction force acting between the driver-side bearing 39 and the driver-side pin 35, the acceleration α acts in a downward direction, as shown by the arrow in FIG. 21. As a result, the driver-side bearing 39 moves in a direction in which the flat surface of the flange 39a comes into contact with the upper flat surface 33c.

[0056] The frictional forces μ1·F2 generated between the driver-side bearing 39 and the driver-side press-fit hole 33b change from an interference fit to a clearance fit, for example, in a high-temperature environment due to a difference in linear expansion coefficient caused by differences in the materials of the driver-side bearing 39 and the intermediate link 33. Even in this case, the driver-side pin 35 is pressed against the driver-side press-fit hole 33b by the radial component force F2 of the tensile load F1, generating frictional forces μ1·F2.

[0057] As the flat surface 39f of the flange 39a of the driver-side bearing 39 moves in a direction coming into contact with the upper flat surface 33f, the relative speed of the flat surface 39f of the flange 39a of the driver-side bearing 39 with respect to the upper flat surface 33f of the rotation pair on the driver side of the intermediate link 33 becomes 0. It is possible to maintain the position of the flat surface 39f of the flange 39a of the driver-side bearing 39 with respect to the upper flat surface 33c of the rotation pair on the driver side of the intermediate link 33.

[0058] As described above, the butterfly-type exhaust throttle device 1 according to the first embodiment includes the electric actuator 42 that rotates the output shaft 41, the throttle body 21 in which the exhaust flow path 21a is formed, the throttle valve shaft 23 to which the throttle valve 22 is attached, and the four-bar link mechanism 3 that connects the output shaft 41 of the electric actuator 42 to the throttle valve shaft 23. The four-bar link mechanism 3 includes a driver 34 attached to the output shaft 41 of the electric actuator 42, a follower 31 attached to the throttle valve shaft 23, and an intermediate link 33 that connects the driver 34 to the follower 31 and has bearings press-fitted into both the driver-side and follower-side rotation pairs. The intermediate link 33 is inclined relative to the direction perpendicular to the bearing axial direction, with the bearing press-fit position of the driver-side rotation pair and the bearing press-fit position of the follower-side rotation pair being positioned at different positions relative to the bearing axial direction. Because the intermediate link 33 is inclined relative to a direction perpendicular to the central axis on a cross section including the axial centers of the two rotational pairs in the intermediate link 33, the mounting position of the electric actuator 42 can be brought closer to the central axis of the exhaust flow path 21a formed in the throttle body 21. This makes it possible to reduce the size and weight of the butterfly-type exhaust throttle device 1. Furthermore, in order for the heat of the fluid passing through the exhaust flow path 21a to be transferred to the electric actuator 42, a long heat transfer path is required, passing through the throttle body 21, the follower link 31, the intermediate link 33, and the driver link 34. For this reason, it is generally possible to use a lightweight, low-heat-resistant material for the electric actuator 42.

[0059] In the butterfly-type exhaust throttle device 1 according to the first embodiment, the intermediate link 33 of the four-bar link mechanism 3 is arc-shaped. The movable ranges of the driven link 31, intermediate link 33 and driver link 34 that make up the four-bar link mechanism 3 can be arranged in the vicinity of the throttle valve shaft 23, so the axial length of the exhaust flow path 21a of the throttle body 21 can be shortened, enabling the butterfly-type exhaust throttle device 1 to be made smaller and lighter.

[0060] In the butterfly-type exhaust throttle device 1 according to the first embodiment, the end of the output shaft 41 of the electric actuator 42 is positioned vertically lower than the position of the end 23a of the throttle valve shaft 23 to which the follower 31 is attached, and closer to the central axis of the exhaust passage 21a, when viewed from the direction of the central axis of the exhaust passage 21a of the throttle body 21. This allows the mounting position of the electric actuator 42 to be closer to the central axis of the exhaust passage 21a formed in the throttle body 21, making it possible to reduce the size and weight of the butterfly-type exhaust throttle device 1.

[0061] In the butterfly-type exhaust throttle device 1 according to the first embodiment, the bearings press-fitted into the revolute pairs in the intermediate link 33 are made of carbon, which makes it possible to reduce the weight of the butterfly-type exhaust throttle device 1 compared to bearings made of heat-resistant metal.

[0062] In the butterfly-type exhaust throttle device 1 according to the first embodiment, the bearing press-fitted into the revolute pair of the intermediate link 33 has a flanged shape with a collar. When the end of the output shaft 41 of the electric actuator 42 to which the driving link 34 is connected faces downward, in a cross section including the axes of both revolute pairs of the intermediate link 33, a bearing is press-fitted into the upper of the two revolute pairs of the intermediate link 33 with the collar facing downward, and a bearing is press-fitted into the lower of the two revolute pairs with the collar facing upward. The power of the electric actuator 42 accelerates the collar of the bearing in a direction pushing the intermediate link 33, preventing the bearing from falling off the revolute pair of the intermediate link 33. This reduces wear due to sliding between the bearing and the intermediate link 33, and reduces a decrease in the power transmission efficiency of the electric actuator 42.

[0063] Embodiment 2. In embodiment 1, a configuration was shown in which a bearing is press-fitted into the upper of the two revolute pairs of the intermediate link with the flange facing downward, and a bearing is press-fitted into the lower of the two revolute pairs with the flange facing upward. In embodiment 2, a configuration will be described in which a bearing is press-fitted into each of the two revolute pairs of the intermediate link with the flange facing upward in a cross section that includes the axes of both of the two revolute pairs of the intermediate link.

[0064] The four-bar link mechanism provided in the butterfly-type exhaust throttle device of embodiment 2 is similar to embodiment 1 in that the driven link is connected to one of the revolute pairs of the intermediate link via a driven link side pin, and the driver link is connected to the other revolute pair of the intermediate link via a driver link side pin.

[0065] 22 is a side view showing the appearance of the four-bar link mechanism of the butterfly-type exhaust throttle device 1 according to embodiment 2. A follower-side pin 32 is inserted into a follower-side bearing 38 press-fitted into the rotational pair on the follower side of the intermediate link 33, and is prevented from coming off by a washer 36 and a retaining ring 37. Similarly, a driver-side pin 35 is inserted into a driver-side bearing 39 press-fitted into the rotational pair on the driver side of the intermediate link 33, and is prevented from coming off by a washer 36 and a retaining ring 37. The rotation of the follower 31 is stopped by a stopper locking portion 31b on the throttle body 21.

[0066] As in the first embodiment, the follower-side bearing 38 is composed of a flange 38a and a cylindrical portion 38b with one end integrally formed with the flange 38a. In Figure 22, it is assumed that the end of the output shaft 41 to which the driver 34 is connected faces downward in a cross section including the axes of both rotation pairs of the intermediate link 33. In the intermediate link 33 in the second embodiment, the flange of the follower-side bearing 38 is attached to the follower-side rotation pair so that it is above the follower-side rotation pair. That is, the cylindrical portion 38b is press-fitted and fixed into a press-fit hole 33b provided in the follower-side rotation pair of the intermediate link 33 so that the flat surface of the flange 38a and the upper flat surface 33c of the follower-side rotation pair are in surface contact. As in the first embodiment, the driver-side bearing 39 is mounted so that the flange 39a is on the upper side of the rotation pair on the driver side.

[0067] (Action of Force at the Rotation Pair on the Follower Side of the Intermediate Link) Figure 23 is a cross-sectional view showing the press-fitting of the follower-side pin into the rotation pair on the follower side of the intermediate link 33 in embodiment 2. As shown in Figure 23, one end of the follower-side pin 32 is press-fit into the press-fit hole 31c of the follower 31, and the other end is inserted into the follower-side bearing 38. The cylindrical portion 38b of the follower-side bearing 38 is press-fit into the rotation pair on the follower side of the intermediate link 33, with the flange portion 38a facing upward. The end of the follower-side pin 32 inserted into the follower-side bearing 38 is prevented from coming out by a washer 36 and a retaining ring 37.

[0068] 23, the radial component force F2 causes the inner periphery of the press-fit hole 33b of the follower-side rotation pair in the intermediate link 33 to come into contact with the outer periphery 38d of the cylindrical portion 38b of the follower-side bearing 38, and also causes the outer periphery 32a of the follower-side pin 32 to come into contact with the inner periphery 38e of the cylindrical portion 38b of the follower-side bearing 38. If the coefficient of friction between the follower-side bearing 38 and the follower-side press-fit hole 33b is μ1, then a frictional force μ1·F2 generated between the follower-side bearing 38 and the follower-side press-fit hole 31c occurs downward, which is the opposite direction to the axial component force.

[0069] The mass of the follower-side bearing 38 is defined as M, and the gravitational acceleration is defined as g. The gravitational force M·g acting on the follower-side bearing 38 is generated in the downward direction. The coefficient of friction between the follower-side bearing 38 and the follower-side pin 32 is defined as μ2. In this case, the frictional force μ2·F2 generated between the follower-side bearing 38 and the follower-side pin 32 is generated in the upward direction, which is the opposite direction to the frictional force μ1·F2. As a result, the acceleration α acting in the axial direction of the follower-side bearing 38 is given by α=μ2·F2 / M-μ1·F2 / M-g.

[0070] At this time, if the resultant force of the gravity of the follower-side bearing 38 and the frictional force generated between the follower-side bearing 38 and the follower-side press-fit hole 33b is greater than the frictional force generated between the follower-side bearing 38 and the follower-side pin 32, the acceleration α acts in the downward direction shown by the arrow in Figure 23. As a result, the follower-side bearing 38 moves in a direction in which the flat surface 38f of the flange 38a comes into contact with the lower flat surface 33d.

[0071] The frictional force μ1·F2 generated between the follower-side bearing 38 and the follower-side press-fit hole 33b changes from an interference fit to a clearance fit, for example, in a high-temperature environment due to a difference in linear expansion coefficient caused by a difference in the materials of the follower-side bearing 38 and the intermediate link 33. Even in this case, the radial component force F2 of the tensile load F1 presses the follower-side pin 32 against the follower-side press-fit hole 33b, generating frictional forces μ1·F2.

[0072] As the flat surface 38f of the flange 38a of the follower-side bearing 38 moves in a direction coming into contact with the upper flat surface 33c, the relative velocity of the flat surface 38f of the flange 38a of the follower-side bearing 38 with respect to the upper flat surface 33c of the rotation pair on the follower side of the intermediate link 33 becomes 0. It is possible to maintain the position of the flat surface 38f of the flange 38a of the follower-side bearing 38 with respect to the upper flat surface 33c of the rotation pair on the follower side of the intermediate link 33.

[0073] As described above, in the butterfly-type exhaust throttle device 1 according to the second embodiment, the bearings press-fitted into the revolute pairs of the intermediate link 33 have a flanged shape with a collar. When the end of the output shaft 41 of the electric actuator 42 to which the driver link 34 is connected faces downward, in a cross section including both axes of the two revolute pairs of the intermediate link 33, the bearings are press-fitted into the two revolute pairs of the intermediate link 33 with the collars facing upward. The power of the electric actuator 42 accelerates the collars of the bearings in a direction that presses against the intermediate link 33, preventing the bearings from falling off the revolute pairs of the intermediate link 33. This reduces wear due to sliding between the bearings and the intermediate link 33, and prevents a decrease in the efficiency of power transmission of the electric actuator 42.

[0074] It is possible to combine the embodiments, modify any of the components of the embodiments, or omit any of the components of the embodiments.

[0075] The butterfly-type exhaust throttle device according to the present disclosure can be used, for example, in an internal combustion engine of an automobile.

[0076] REFERENCE SIGNS LIST 1, 1A, 1B butterfly-type exhaust throttle device, 2 throttle body portion, 3 four-bar link mechanism, 4 actuator portion, 5 bracket, 5a screw, 21, 21A throttle body, 21a exhaust flow path, 21b spring engagement portion, 21c full-open stopper, 21d threaded hole, 22 throttle valve, 22a pin, 23 throttle valve shaft, 23a, 24a, 24b end portion, 24 spring, 31 follower, 31a press-fit hole, 31b stopper engagement portion, 31c press-fit hole, 32 follower-side pin, 32a outer periphery, 33, 33A, 33B intermediate link, 33a joint portion, 33b press-fit hole, 33c upper flat portion, 33d lower flat portion, 33e press-fit hole, 33f upper flat portion, 33g Lower flat portion, 34: driver, 34a: press-fit hole, 34b: press-fit hole, 35: driver-side pin, 35a: outer periphery, 36: washer, 37: retaining ring, 38: follower-side bearing, 38a: flange, 38b: cylindrical portion, 38c: hole, 38d: outer periphery, 38e: inner periphery, 38f: flat portion, 39: driver-side bearing, 39a: flange, 39b: cylindrical portion, 39c: hole, 39d: outer periphery, 39e: inner periphery, 39f: flat portion, 41: output shaft, 41a: press-fit portion, 41b: male thread portion, 42: electric actuator, 42a: screw hole, 44: nut.

Claims

1. A butterfly-type exhaust throttle device for an internal combustion engine comprising: an electric actuator that rotates an output shaft; a throttle body having a flow passage; a throttle valve shaft having a throttle valve attached; and a four-bar linkage connecting the output shaft of said electric actuator and said throttle valve shaft, wherein said four-bar linkage has: a driver attached to the output shaft of said electric actuator; a driven link attached to the throttle valve shaft; and an intermediate link connecting said driver and driven links, with bearings attached to both the driver-side rotation pair and the driven-side rotation pair, wherein the intermediate link is arranged so that the bearing press-fit position of the driver-side rotation pair and the bearing press-fit position of the driven-side rotation pair are different from each other in the axial direction of the bearing, and is inclined relative to a direction perpendicular to the axial direction of the bearing.

2. A butterfly-type exhaust throttle device as set forth in claim 1, characterized in that the intermediate link of the four-link mechanism is arc-shaped.

3. A butterfly-type exhaust throttle device as described in claim 1 or claim 2, characterized in that the end of the output shaft of the electric actuator is positioned vertically below the position of the end of the throttle valve shaft to which the follower is attached, and toward the central axis of the flow passage, when viewed from the direction of the central axis of the flow passage of the throttle body.

4. A butterfly-type exhaust throttle device as set forth in claim 1, characterized in that the bearing press-fitted into the revolute pair in the intermediate section is made of carbon.

5. A butterfly-type exhaust throttle device as claimed in claim 1 or claim 4, characterized in that the bearing pressed into the revolute pair in the intermediate section has a flange shape with a flange, and when the direction of the end of the output shaft of the electric actuator connected to the driving section is downward, in a cross section that includes both axis centers of the two revolute pairs of the intermediate section, of the two revolute pairs of the intermediate section, a bearing is pressed into the upper revolute pair with the flange on the bottom, and a bearing is pressed into the lower revolute pair with the flange on the top.

6. A butterfly-type exhaust throttle device as described in claim 1 or claim 4, characterized in that the bearings pressed into the revolute pairs in the intermediate section have a flanged shape with a flange, and when the direction of the end of the output shaft of the electric actuator connected to the driving section is downward, in a cross section that includes both axis centers of the two revolute pairs of the intermediate section, the bearings are pressed into each of the two revolute pairs of the intermediate section with the flange facing up.

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