JP7006122B2 - Actuator - Google Patents

Description

The present invention relates to an actuator that drives a valve for controlling boost pressure of a supercharger.

Conventionally, an actuator that is connected to a boost pressure control valve via a link mechanism or the like and adjusts the valve opening degree to control the boost pressure is known. The actuator disclosed in Patent Document 1 decelerates the rotation of the motor at the deceleration section and outputs the motor from the output shaft. The gear of the reduction gear is made of resin and is rotatably supported by a metal shaft.

Japanese Unexamined Patent Publication No. 2017-8757

The supercharging pressure control valve regulates the amount of hot exhaust gas entering the supercharger. Therefore, the mounting environment of the actuator becomes high temperature. In such a high temperature environment, if the linear expansion difference between the gear of the reduction portion of the actuator and the shaft supporting the gear is large, the clearance between the sliding surfaces of both members becomes large and the gear tilts. When the force applied to the boost pressure control valve due to the exhaust pulsation acts on the gear via the link mechanism, the gear cannot rotate stably, and the tooth surface and sliding surface of the gear may be unevenly worn. There is.

The present invention has been made in view of the above points, and an object of the present invention is to provide an actuator with improved durability.

The actuator of the present invention includes a motor (36), an output shaft (38), a speed reducer (37), a metal shaft (75, 76, 101, 102), and a housing (35). The speed reducer includes one or more metal gears (52, 53, 103, 104) to slow down the rotation of the motor and transmit it to the output shaft. The metal shaft is fitted in the axial core holes (77, 78) of the metal gear and rotatably supports the metal gear. The housing houses the motor and reduction gear and supports the output shaft and metal shaft. The metal shaft includes a press-fitting portion (81) that is press-fitted into the press-fitting hole (85) of the housing, and a coating portion (83) that includes a portion that slides with the metal gear and is provided with a lubricating coating (87, 105). It has an intermediate portion (82), which is located between the press-fitted portion and the coating portion and does not require lubrication performance. The lubricating film is provided in addition to the press-fitting portion. A chamfer (93) is formed at the end of the shaft center hole on the press-fitting hole side. A chamfer (91) is formed at the end of the press-fit hole on the axial center hole side. A washer (95) is provided between the shaft center hole and the press-fit hole. The axial distance from the end of the press-fitting surface (94) on the press-fitting hole side to the end of the sliding surface (92) of the press-fitting hole on the press-fitting hole side is defined as A, and the axial length of the intermediate portion is defined as the axial length. Assuming B, there is a relationship of A ≧ B.

By forming the gear of the reduction portion and the shaft supporting the shaft from the same metal material in this way, the difference in linear expansion between the two members becomes small. As a result, the clearance between the sliding surfaces of both members when used in a high temperature environment is smaller than that of the combination of the resin gear and the metal shaft, and the inclination of the gear can be suppressed. Therefore, even if the force due to the exhaust pulsation acts on the gear, the gear rotates stably, so that uneven wear of the tooth surface and the sliding surface of the gear can be suppressed. Therefore, the durability of the actuator is improved.

Here, in the case of a combination of a metal gear and a metal shaft, wear due to sliding of both members becomes a problem. To solve this problem, it is conceivable to provide bearing parts between both members. However, if bearing parts are provided, there is a drawback that the manufacturing cost increases and the actuator becomes large due to the large diameter of the gear, which reduces the mountability.

On the other hand, since the actuator of the present invention is provided with the lubricating film as described above, it is possible to reduce wear due to sliding between the metal gear and the metal shaft without providing bearing parts. Further, since the bearing component is not provided, it is possible to avoid increasing the diameter of the gear and the resulting increase in the size of the actuator.

It is a schematic diagram of the intake / exhaust part of the engine to which the actuator according to 1st Embodiment is applied. It is explanatory drawing of a supercharger. It is a perspective view of an actuator. It is a top view of the actuator. FIG. 4 is a sectional view taken along line VV of FIG. FIG. 4 is a sectional view taken along line VI-VI of FIG. It is a figure which shows the state which the 2nd housing part and the like of the actuator of FIG. 4 were removed. It is a figure which shows the 1st intermediate gear and a metal shaft. It is an enlarged view of the IX part of FIG. FIG. 8 is a cross-sectional view taken along the line XX of FIG. It is a figure which shows the 1st intermediate gear and the metal shaft of the actuator by 2nd Embodiment.

[First Embodiment]
Hereinafter, a plurality of embodiments will be described with reference to the drawings. In a plurality of embodiments, substantially the same configuration is designated by the same reference numeral, and the description thereof will be omitted. As shown in FIG. 1, the actuator 10 according to the first embodiment is applied to an engine 11 which is a power source for traveling a vehicle.

(Intake / exhaust part of engine)
First, the intake / exhaust portion of the engine 11 will be described with reference to FIGS. 1 and 2. The engine 11 is provided with an intake passage 12 that guides intake air into the cylinder of the engine 11, and an exhaust passage 13 that exhausts exhaust gas generated in the cylinder to the atmosphere. In the middle of the intake passage 12, an intake compressor 15 of the supercharger 14 and a throttle valve 16 for adjusting the amount of intake air supplied to the engine 11 are provided. In the middle of the exhaust passage 13, an exhaust turbine 17 of the supercharger 14 and a catalyst 18 for purifying the exhaust gas are provided. The catalyst 18 is a well-known three-way catalyst that adopts a monolithic structure, and purifies harmful substances contained in exhaust gas by an oxidizing action and a reducing action by raising the temperature to the activation temperature.

The exhaust turbine 17 includes a turbine wheel 21 that is rotationally driven by the exhaust gas discharged from the engine 11 and a spiral-shaped turbine housing 22 that houses the turbine wheel 21. The intake compressor 15 includes a compressor wheel 23 that rotates by receiving the rotational force of the turbine wheel 21, and a spiral compressor housing 24 that houses the compressor wheel 23.

The turbine housing 22 is provided with a bypass passage 25 that bypasses the turbine wheel 21 and allows exhaust gas to flow. The bypass passage 25 directly guides the exhaust gas flowing into the turbine housing 22 to the exhaust outlet of the turbine housing 22. The bypass passage 25 can be opened and closed by the wastegate valve 26. The wastegate valve 26 is a swing valve rotatably supported by a valve shaft 27 inside the turbine housing 22.

As a means for driving the wastegate valve 26, the supercharger 14 includes an actuator 10. The actuator 10 is attached to an intake compressor 15 away from the exhaust turbine 17 for the purpose of avoiding the thermal influence of the exhaust gas. The supercharger 14 is provided with a link mechanism 29 for transmitting the output of the actuator 10 to the wastegate valve 26. This link mechanism 29 is a so-called four-node link, and is a valve that applies a rotation torque applied to an actuator lever 31 that is rotationally operated by an actuator 10, a valve lever 32 that is coupled to a valve shaft 27, and an actuator lever 31. It has a rod 33 that transmits to the lever 32.

The actuator 10 is controlled by an ECU (engine control unit) 34 equipped with a microcomputer. Specifically, the ECU 34 adjusts the opening degree of the wastegate valve 26 when the engine 11 rotates at a high speed to control the supercharging pressure by the supercharger 14. Further, the ECU 34 warms up the catalyst 18 by fully opening the wastegate valve 26 when the temperature of the catalyst 18 does not reach the activation temperature, such as immediately after a cold start. As a result, the high-temperature exhaust gas that has not been deprived of heat by the turbine wheel 21 can be guided to the catalyst 18, and the catalyst 18 can be warmed up early.

(Actuator)
Next, the actuator 10 will be described with reference to FIGS. 3 to 7. The actuator 10 includes a housing 35 attached to the intake compressor 15, a motor 36 assembled to the housing 35, a deceleration unit 37, an output shaft 38, and a rotation angle sensor 39.

As shown in FIGS. 3 to 5, the housing 35 has a first housing portion 41 and a second housing portion 42. The second housing portion 42 is fastened to the first housing portion 41 by the fastening member 43. Further, the first housing portion 41 forms an accommodation space 44 together with the second housing portion 42. The first housing portion 41 and the second housing portion 42 are made of a metal material such as an aluminum alloy and are die-cast.

As shown in FIGS. 6 and 7, the motor 36 is housed in the housing 35. Specifically, the motor 36 is inserted into the motor insertion hole 46 formed in the first housing portion 41, and is fixed to the first housing portion 41 by the screw 47. The motor 36 may be, for example, a well-known DC motor or a well-known stepping motor regardless of the type.

As shown in FIG. 5, the output shaft 38 is rotatably supported by a bearing 48 provided in the first housing portion 41 and a bearing 49 provided in the second housing portion 42. One end of the output shaft 38 extends out of the housing 35. The actuator lever 31 is fixed to the output shaft outside the housing 35.

As shown in FIGS. 5 to 7, the reduction gear 37 is a parallel shaft type reduction gear that decelerates the rotation of the motor 36 and transmits the rotation to the output shaft 38, and is a pinion gear 51, a first intermediate gear 52, and a second intermediate. It has a gear 53 and a final gear 54. The pinion gear 51 is fixed to the motor shaft 55 of the motor 36. The first intermediate gear 52 has a first large-diameter external tooth portion 57 that meshes with the pinion gear 51, and a first small-diameter external tooth portion 58 that has a smaller diameter than the first large-diameter external tooth portion 57. The second intermediate gear 53 includes a second large-diameter external tooth portion 62 that meshes with the first small-diameter external tooth portion 58, and a second small-diameter external tooth portion 63 that has a smaller diameter than the second large-diameter external tooth portion 62. Have. The final gear 54 is fixed to the output shaft 38 and meshes with the second small diameter external tooth portion 63.

As shown in FIGS. 5 and 7, the rotation angle sensor 39 is a non-contact type sensor that detects the rotation angle of the output shaft 38, and has a magnetic circuit unit 64 and a detection unit 65. The magnetic circuit unit 64 has magnets 66 and 67 which are magnetic flux generation units and yokes 68 and 69 which are magnetic flux transmission units. The magnets 66, 67 and the yokes 68, 69 form an arcuate closed magnetic circuit in the axial view of the output shaft 38. The magnetic circuit unit 64 is held by a non-magnetic magnetic circuit holding member 73, and rotates integrally with the output shaft 38. The detection unit 65 is, for example, a Hall IC or the like, and is arranged inside the closed magnetic circuit of the magnetic circuit unit 64. The detection unit 65 is molded into a wiring holding member 71 made of an insulator and is fixed to the housing 35. The basic uses and functions of the magnetic circuit unit 64 and the detection unit 65 are the same as those disclosed in Japanese Patent Application Laid-Open No. 2014-126548. The rotation angle of the output shaft 38 detected by the rotation angle sensor 39 is output to the ECU 34 (see FIG. 1).

(Deceleration part and its peripheral members)
Next, the deceleration unit 37 and its peripheral members will be described. As shown in FIGS. 5 and 6, the gears of the reduction gear 37, that is, the pinion gear 51, the first intermediate gear 52, the second intermediate gear 53, and the final gear 54 are metal gears and are made of iron-based sintered metal. .. Hereinafter, when a plurality of gears of the reduction unit 37 will be described, they will be appropriately referred to as "metal gears".

As shown in FIGS. 5 to 7, the actuator 10 includes metal shafts 75 and 76. The metal shaft 75 is fitted in the axial center hole 77 of the first intermediate gear 52, and rotatably supports the first intermediate gear 52. The metal shaft 76 is fitted in the shaft center hole 78 of the second intermediate gear 53, and rotatably supports the second intermediate gear 53.

The metal shaft 75 and the metal shaft 76 have the same configuration. Hereinafter, the metal shaft 75 will be described as a representative of these. As shown in FIG. 8, the metal shaft 75 has a press-fitting portion 81, an intermediate portion 82, a coating portion 83, and a fitting portion 84.

The press-fitting portion 81 is one end of the metal shaft 75 on the first housing portion 41 side, and is press-fitted into the press-fitting hole 85 of the first housing portion 41. The fitting portion 84 is the other end of the metal shaft 75 on the second housing portion 42 side, and is fitted into the fitting hole 86 of the second housing portion 42.

The coating portion 83 includes a portion that slides on the first intermediate gear 52. A lubricating film 87 is provided on the film portion 83. The "lubricating film" is a film formed of a solid lubricant. In FIG. 8, the lubricating film 87 is shown by a broken line grid pattern. The lubrication film 87 provided on the film portion 83 is required to have a certain level of lubrication performance. This lubrication performance is determined by the film thickness and hardness of the lubricating film 87. The lubricating film 87 is provided in addition to the press-fitting portion 81. That is, the press-fitting portion 81 is not provided with the lubricating film 87. In the first embodiment, the lubricating film 87 is provided on the fitting portion 84 and the coating portion 83. The lubricating film 87 is a DLC (Diamond-Like Carbon) film.

The intermediate portion 82 is located between the press-fit portion 81 and the coating portion 83, and lubrication performance is not required. That is, even if the intermediate portion 82 is provided with a lubricating film, the film does not need a film thickness and hardness to obtain a certain level of lubrication performance.

As shown in FIG. 9, a chamfer 93 is formed at the end of the shaft core hole 77 on the press-fitting hole 85 side. The sliding surface 92 of the axial core hole 77 is a portion of the axial core hole 77 other than the chamfer 91. A chamfer 91 is formed at the end of the press-fit hole 85 on the first intermediate gear 52 side. The press-fitting surface 94 of the press-fitting hole 85 is a portion of the inner wall surface of the press-fitting hole 85 other than the chamfer 93. A washer 95 is provided between the first intermediate gear 52 and the first housing portion 41 (that is, between the shaft center hole 77 and the press-fit hole 85).

Let A be the axial distance from the end of the press-fitting surface 94 of the press-fitting hole 85 on the first intermediate gear 52 side to the end of the sliding surface 92 of the axial core hole 77 on the press-fitting hole 85 side. Further, the axial length of the intermediate portion 82 is B. These axial distances A and axial lengths B have a relationship of the following equation (1).
A ≧ B ・ ・ ・ (1)

The metal shaft 75 is made of a material having a relatively high surface hardness, and has a higher surface hardness than, for example, the output shaft 38. The output shaft 38 may be strong enough to be supported by the bearing and is made of stainless steel such as, for example, SUS430 or SUS304. On the other hand, the metal shaft 75 is made of, for example, a heat-treated tool steel SKH51 (HRC60 or higher) in order to prevent the lubricating film 87 from peeling off by suppressing deformation.

A lubricant is applied between the coating portion 83 and the first intermediate gear 52. The lubricant is, for example, lubricating grease or lubricating oil.

As shown in FIG. 10, the minimum tooth width of the first small-diameter external tooth portion 58 is defined as C. Further, the radial distance from the tooth bottom 96 of the first small diameter outer tooth portion 58 to the outer peripheral surface 97 of the metal shaft 75 is defined as D. The minimum width C of the tooth root and the radial distance D have a relationship of the following equation (2).
C ≦ D ≦ 1.4C ・ ・ ・ (2)

(effect)
As described above, the actuator 10 includes a motor 36, an output shaft 38, a speed reducing unit 37, metal shafts 75 and 76, and a housing 35. The reduction gear 37 includes a first intermediate gear 52 and a second intermediate gear 53, which are metal gears. The metal shafts 75 and 76 are fitted in the axial core holes 77 and 78 of the intermediate gears 52 and 53, and rotatably support the intermediate gears 52 and 53. The housing 35 houses the motor 36 and the speed reducer 37, and supports the output shaft 38 and the metal shafts 75 and 76. The metal shafts 75 and 76 are provided with a lubricating film 87 at least on a portion sliding with the intermediate gears 52 and 53.

By forming the intermediate gears 52 and 53 and the metal shafts 75 and 76 supporting the intermediate gears 52 and 53 from the same kind of metal, the difference in linear expansion between the two members becomes small. As a result, the clearance between the sliding surfaces of both members becomes smaller when used in a high temperature environment, and the inclination of the intermediate gears 52 and 53 can be suppressed as compared with the form of the combination of the resin gear and the metal shaft. .. Therefore, even if the force due to the exhaust pulsation acts on the intermediate gears 52 and 53, they rotate stably, so that uneven wear of the tooth surface and the sliding surface of the intermediate gears 52 and 53 can be suppressed. Therefore, the durability of the actuator 10 is improved.

Here, in the case of a combination of a metal gear and a metal shaft, wear due to sliding of both members becomes a problem. To solve this problem, it is conceivable to provide bearing parts between both members. However, if bearing parts are provided, there is a drawback that the manufacturing cost increases and the actuator becomes large due to the large diameter of the gear, which reduces the mountability.

On the other hand, since the actuator 10 is provided with the lubricating film 87 as described above, it is possible to reduce wear due to sliding between the intermediate gears 52 and 53 and the metal shafts 75 and 76 without providing bearing parts. can. Further, since it does not have a bearing component, it is possible to avoid increasing the diameter of the intermediate gears 52 and 53 and thereby increasing the size of the actuator 10.

Further, in the first embodiment, the metal shafts 75 and 76 have a press-fitting portion 81 press-fitted into the press-fitting hole 85 of the first housing portion 41. The lubricating film 87 is provided in addition to the press-fitting portion 81. The metal shafts 75 and 76 have a higher surface hardness than the output shaft 38. By not providing the coating on the press-fitting portion 81 which is not necessary for sliding in this way, the manufacturing cost can be reduced and the press-fitting holding force of the metal shafts 75 and 76 can be increased. Further, by increasing the surface hardness of the metal shafts 75 and 76 to suppress deformation, peeling of the lubricating film 87 can be suppressed.

Further, in the first embodiment, the metal shafts 75 and 76 are located between the press-fitting portion 81, the coating portion 83 provided with the lubricating coating 87, and the press-fitting portion 81 and the coating portion 83, and require lubrication performance. It has an intermediate portion 82 that does not. The axial distance A and the axial length B are in the relationship of the above equation (1). Here, if a boundary is provided so that the presence or absence of a coating is switched between the press-fitting portion 81 and the coating portion 83, a high-precision jig is required at the time of manufacturing, which requires cost and man-hours for jig maintenance and the like, and is manufactured. The cost will be high. On the other hand, by providing the intermediate portion 82 which does not require the lubrication performance, the accuracy of the jig used at the time of manufacturing can be lowered. Therefore, the cost and man-hours for jig maintenance and the like are reduced, and the manufacturing cost is lowered.

Further, in the first embodiment, the lubricating film 87 is a DLC film. As a result, it is possible to realize the same low friction sliding as when the bearing component is provided by the lubricating film 87.

Further, in the first embodiment, the intermediate gears 52 and 53 have small diameter external tooth portions 58 and 63 and large diameter external tooth portions 57 and 62. The tooth root minimum width C and the radial distance D are in the relationship of the above equation (1). This relationship is established by realizing low friction sliding by the lubricating film 87 and omitting bearing parts. Therefore, the outer diameters of the small diameter outer teeth portions 58 and 63 become smaller, and the actuator 10 can be miniaturized.

Further, in the first embodiment, a lubricant is applied between the metal shafts 75 and 76 and the intermediate gears 52 and 53. As a result, the friction between the metal shafts 75 and 76 and the intermediate gears 52 and 53 is further reduced, the wear of the bearing portion is reduced, and the durability of the actuator 10 is further improved. Further, it has a damping effect on the exhaust pulsation, and wear of the shaft core holes 77 and 78 of the intermediate gears 52 and 53 and the lubricating film 87 of the metal shafts 75 and 76 due to the impact is suppressed.

[Second Embodiment]
In the second embodiment, as shown in FIG. 11, the metal shafts 101 and 102 are not provided with a coating film. Instead, the intermediate gears 103 and 104 are provided with a lubricating film 105 at a portion sliding with the metal shafts 75 and 76. In this way, the lubricating film 105 may be provided on the sliding portions of the intermediate gears 103 and 104. Nevertheless, it is possible to reduce wear due to sliding between the intermediate gears 103 and 104 and the metal shafts 101 and 102 without providing bearing parts.

[Other embodiments]
In another embodiment, the lubricating film may not be provided on the fitting portion of the metal shaft, but may be provided only on the coated portion. In short, the lubricating film may be provided on a portion of one of the intermediate gear and the metal shaft that slides on the other. Further, the lubricating film is not limited to the DLC film, and may be, for example, a titanium aluminum nitride film or a molybdenum disulfide film. The lubricating film is formed by forming a solid lubricant such as graphite (graphite), polytetrafluoroethylene (PTFE), graphite fluoride, boron nitride, tungsten disulfide, and melamine cyanurate into a film. May be good.

In other embodiments, no lubricant may be applied between the intermediate gear and the metal shaft. Further, the intermediate gear of the reduction portion is not limited to the iron-based sintered metal, and may be made of another metal. Further, the metal shaft is not limited to the tool steel SKH51, and may be made of another metal. In short, the intermediate gear and the metal shaft need not be made of different materials such as resin and metal, but may be made of the same kind of metal and metal. Further, the metal shaft is not provided with an intermediate portion, and a boundary may be provided so that the presence or absence of a coating is switched between the press-fitting portion and the coating portion.

The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the invention.

10 ... Actuator 35 ... Housing 36 ... Motor 37 ... Deceleration unit 38 ... Output shaft 52, 53, 103, 104 ... Metal gear 65 ... Detection unit 75, 76, 101 , 102 ... Metal shaft 77, 78 ... Axial core hole 87, 105 ... Lubricating film

Claims (5)

An actuator that drives a valve (26) for controlling the supercharging pressure of the supercharger (14).
With the motor (36)
Output shaft (38) and
A deceleration unit (37) comprising one or more metal gears (52, 53, 103, 104) that decelerates the rotation of the motor and transmits it to the output shaft.
A metal shaft (75, 76, 101, 102) that is fitted in the shaft center hole (77, 78) of the metal gear and rotatably supports the metal gear.
A housing (35) that houses the motor and the deceleration unit and supports the output shaft and the metal shaft.
Equipped with
The metal shaft includes a press-fitting portion (81) press-fitted into the press-fitting hole (85) of the housing and a portion sliding with the metal gear , and is provided with a lubricating film ( 87, 105). It has an intermediate portion (82) located between the press-fitting portion and the coating portion and which does not require lubrication performance.
The lubricating film is provided in a place other than the press-fitting portion.
A chamfer (93) is formed at the end of the axial core hole on the press-fitting hole side.
A chamfer (91) is formed at the end of the press-fitting hole on the axial core hole side.
A washer (95) is provided between the axial core hole and the press-fitting hole.
Let A be the axial distance from the end of the press-fitting surface (94) of the press-fitting hole on the axial core hole side to the end of the sliding surface (92) of the axial core hole on the press-fitting hole side.
Assuming that the axial length of the intermediate portion is B,
A ≧ B
Actuator in the relationship . The actuator according to claim 1, wherein the metal shaft has a higher surface hardness than the output shaft. The actuator according to claim 1 or 2 , wherein the lubricating film is a DLC film, a titanium aluminum nitride film, or a molybdenum disulfide film. The metal gear has a small-diameter external tooth portion (58, 63) and a large-diameter external tooth portion (57, 62).
Let C be the minimum width of the tooth root of the small-diameter external tooth portion.
Let D be the radial distance from the tooth bottom (96) of the small diameter outer tooth portion to the outer peripheral surface (97) of the metal shaft.
C ≦ D ≦ 1.4C
The actuator according to any one of claims 1 to 3 , which is related to the above. The actuator according to any one of claims 1 to 4 , wherein a lubricant is applied between the metal shaft and the metal gear.

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