JP2011223807A - Electric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow smooth removal of foreign materials in a bearing chamber, which accommodates a bearing for supporting a lower end of a rotary shaft of an electric motor of an electric actuator.SOLUTION: Oil or foreign materials that has entered a bearing chamber 42a can hardly be removed to the outside, when placing the bearing chamber 42a that accommodates a bearing 55 supporting the lower end of a downward extending rotary shaft 54 of an electric motor 48, in a gear housing 42 that contains deceleration gears 58 and 59 decelerating rotation of the rotary shaft 54 of the electric motor 48 to transmit the rotation to an output shaft 24. Through a connecting passage 42c, the bearing chamber 42a is connected with an oil reservoir 42b for storing the oil, located in the gear housing 42 and retaining lubricant for the deceleration gears 58 and 59. Thus the foreign materials can be smoothly removed by allowing the oil in the bearing chamber 42a to flow up to the oil reservoir 42b.

Description

  The present invention relates to an electric actuator that decelerates rotation of a rotating shaft of an electric motor with a reduction gear housed in a gear housing and transmits the reduced speed to an output shaft.

  An actuator device that rotationally drives a control shaft of a variable valve mechanism of an internal combustion engine is fixed to an end of the cylinder head, and oil is supplied from the inside of the cylinder head to the inside of the housing of the actuator device, thereby A device for lubricating a ball screw transmission mechanism housed in a housing is known from Patent Document 1 below.

JP 2007-2669 A

  By the way, when the rotating shaft of the electric motor of the actuator device is arranged downward, the oil stays in the bag-shaped bearing chamber that houses the bearing that supports the lower end of the rotating shaft and is difficult to be discharged. Foreign matter can accumulate on the bottom of the bearing chamber and adversely affect the durability of the bearing.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to enable smooth discharge of foreign matter that has entered a bearing chamber that houses a bearing that supports a lower end of a rotating shaft of an electric motor of an electric actuator. .

  In order to achieve the above object, according to the first aspect of the present invention, in the electric actuator, the rotation of the rotation shaft of the electric motor is reduced by a reduction gear housed in a gear housing and transmitted to the output shaft. The housing includes an oil reservoir that stores oil that lubricates the reduction gear, and a bearing chamber that houses a bearing that supports a lower end of a rotating shaft of the electric motor extending downward, and the bearing chamber is connected via a communication path. An electric actuator is proposed that communicates with the oil reservoir.

  The control shaft 24 of the embodiment corresponds to the output shaft of the present invention, the roller bearing 55 of the embodiment corresponds to the bearing of the present invention, and the worm wheel 58 and the worm 59 of the embodiment are the deceleration of the present invention. Corresponds to the gear.

  According to the first aspect of the present invention, the bearing that supports the lower end of the rotating shaft of the electric motor that extends downward is housed in the gear housing that houses the reduction gear that decelerates the rotation of the rotating shaft of the electric motor and transmits it to the output shaft. If the bearing chamber is provided, oil and foreign matter that have entered the bearing chamber will not be easily discharged to the outside, but the oil reservoir that stores the oil that is provided in the gear housing and lubricates the reduction gear and the bearing chamber are connected via the communication path. Therefore, the oil in the bearing chamber can flow into the oil reservoir and the foreign matter can be smoothly discharged.

The perspective view of the cylinder head of an internal combustion engine. FIG. 2 is a two-direction arrow view of FIG. 1. FIG. 3 is a three-direction arrow view of FIG. 2. FIG. 4 is an enlarged sectional view of a part 4 in FIG. 3. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 6 is a sectional view taken along line 6-6 in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 to 6, a cylinder head 11 of an in-line four-cylinder internal combustion engine includes a lower head 13 coupled to a cylinder block 12 and an upper head 14 coupled to the lower head 13, and the upper head 14 is a head cover. 15 is covered. The lower head 13 is provided with an intake valve and an exhaust valve (not shown), and the upper head 14 is provided with a variable valve mechanism (not shown) for changing the valve timing and valve lift of the intake valve and the exhaust valve.

  The upper head 14 includes a main body portion 16 coupled to the lower head 13, five first cap members 18 coupled to the upper surface of the main body portion 16 with bolts 17, and bolts disposed on the upper surface of the first cap members 18. .., And five third cap members 22... Joined by bolts 21... A control shaft 24 in which four control cams 23 are formed between the main body 16 and the first cap members 18 is rotatably supported, and the first cap member 18 and the second cap member 20. An intake cam shaft 26 having four intake cams 25 formed therebetween is rotatably supported, and an exhaust having four exhaust cams 27 formed between the main body portion 16 and the third cap members 22. The cam shaft 28 is rotatably supported.

  An actuator 30 for reciprocatingly driving the control shaft 24 and a negative pressure pump 31 driven by the exhaust camshaft 28 are provided on the outer surface of the wall portion 29 standing from one end of the main body portion 16 of the upper head 14. Therefore, the actuator 30 reciprocates the control shaft 24 and operates the variable valve mechanism by the control cams 23 provided on the control shaft 24, thereby changing the valve lift and valve timing of the intake valve as the engine valve. be able to.

  Various structures of the variable valve mechanism are known as disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-303765 and Japanese Patent Application Laid-Open No. 2008-045540. It can be applied to the mechanism.

  The actuator 30 fixed to the wall portion 29 of the upper head 14 is configured by stacking a mounting base 41, a gear housing 42, a motor driver 44, and a heat sink 45, and the mounting base 41 and three gear housings 42 are provided. The bolts 46 are fastened to the wall 29 of the upper head 14, and the motor driver 44 and the heat sink 45 are fastened to the gear housing 42 with four bolts 47. An electric motor 48 made of a DC brushless motor is fastened to the side surface of the gear housing 42 with three bolts 49.

  The electric motor 48 includes a stator 52 fixed inside the motor housing 50, a rotor 53 disposed inside the stator 52, and a rotating shaft 54 that rotatably supports the rotor 53. Extends into the gear housing 42 and is rotatably supported by roller bearings 55 and ball bearings 56. On the other hand, the shaft end portion of the control shaft 24 passes through a through hole 29 a formed in the wall portion 29 and extends into the gear housing 42, and a worm wheel 58 fixed thereto with a bolt 57 is formed integrally with the rotary shaft 54. It meshes with the worm 59 made.

  The rotation shaft 54 of the electric motor 48 is disposed obliquely downward with an inclination of approximately 45 ° with respect to the vertical or horizontal direction. With this arrangement, a part of the electric motor 48 protrudes so as to cover the upper portion of the wall portion 29 of the upper head 14, thereby reducing the amount of protrusion of the actuator 30 from the wall portion 29 to the side. be able to.

  As apparent from FIGS. 4 and 6, the roller bearing 55 that supports the lower end of the rotating shaft 54 of the electric motor 48 is accommodated in a bearing chamber 42 a formed in a bag shape at the bottom of the gear housing 42 of the actuator 30. . An oil sump 42b having a shape surrounding the lower half of the worm wheel 58 is formed at the bottom of the gear housing 42 that houses the worm 59 and the worm wheel 58. The lower end of the bearing chamber 42a and the oil reservoir 42b communicate with each other through a communication path 42c.

  As is apparent from FIGS. 5 and 6, oil is supplied to the wall portion 29 of the upper head 14 facing the meshing portions of the worm 59 and the worm wheel 58 so that the inside of the cylinder head 11 communicates with the inside of the gear housing 42. A hole 29b is formed, and an oil discharge hole 29c is formed in the wall portion 29 of the upper head 14 facing the upper portion of the oil reservoir 42b of the gear housing 42 to communicate the inside of the cylinder head 11 with the oil reservoir 42b. .

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  When the electric motor 48 of the actuator 30 is driven, the control shaft 24 rotates via a worm 59 integrally provided on the rotating shaft 54 and a worm wheel 58 meshing with the worm 59, and a control cam provided on the control shaft 24. The valve lift and valve timing of the intake valve are changed by operating the variable valve mechanism at 23.

  Oil that lubricates the variable valve mechanism and the like is present inside the cylinder head 11, and the oil is pumped and passes through the oil supply hole 29 b of the wall portion 29 of the upper head 14 to enter the gear housing 42. Supplied to lubricate the meshing portions of the worm 59 and the worm wheel 58. After the lubrication, the oil staying in the oil reservoir 42b of the gear housing 42 passes through the oil discharge port 29c of the wall portion 29 of the upper head 14 and is discharged into the cylinder head 11 from where it returns to the oil pan of the crankcase. It is.

  Part of the oil supplied from the oil supply port 29 b to the inside of the gear housing 42 lubricates the roller bearing 55 that supports the lower end of the rotating shaft 54. Since the bearing chamber 42a for storing the roller bearing 55 is formed in a bag shape, it is difficult for oil and foreign matter entering the bag chamber 42a to be discharged, but the bearing chamber 42a communicates with the oil reservoir 42b via the communication path 42c. The oil and foreign matter in the bearing chamber 42a are quickly discharged into the oil reservoir 42b, and the durability of the roller bearing 55 is prevented from being lowered by the foreign matter. The foreign matter is returned to the oil pan through the cylinder head 11 together with oil, and is captured by the strainer there.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the actuator 30 is applied to the variable valve mechanism, but the application is not limited to the variable valve mechanism.

  The reduction gear of the present invention is not limited to the worm wheel 58 and the worm 59 of the embodiment.

  Further, the bearing accommodated in the bearing chamber 42a is not limited to the roller bearing 55 of the embodiment.

24 Control shaft (output shaft)
42 Gear housing 42a Bearing chamber 42b Oil reservoir 42c Communication path 48 Electric motor 54 Rotating shaft 55 Roller bearing (bearing)
58 Worm wheel (reduction gear)
59 worm (reduction gear)

Claims (1)

  In the electric actuator in which the rotation of the rotating shaft (54) of the electric motor (48) is decelerated by the reduction gears (58, 59) housed in the gear housing (42) and transmitted to the output shaft (24). ) Includes an oil reservoir (42b) for storing oil for lubricating the reduction gears (58, 59), and a bearing (55) for supporting the lower end of the rotating shaft (54) of the electric motor (48) extending downward. An electric actuator comprising a bearing chamber (42a) for housing, wherein the bearing chamber (42a) communicates with the oil reservoir (42b) via a communication path (42c).

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