JP6020139B2 - Actuator - Google Patents

Description

  The present invention relates to a rotation / linear motion conversion type actuator that reciprocates an output shaft in conjunction with rotation of a rotation portion.

  Japanese Patent Application Laid-Open No. 2004-228561 describes a rotation / linear motion conversion type actuator that reciprocates an output shaft supported by a housing so as to be reciprocally movable in conjunction with rotation of a rotation portion. In such an actuator, a stopper is provided on the output shaft, and the stopper is brought into contact with the inner wall of the housing to restrict the reciprocation of the output shaft. Further, in this actuator, an oil discharge path for discharging the oil in the housing to the outside is formed in the housing.

JP 2012-145084 A

  By the way, since the radial load of the output shaft acts on the portion of the housing that supports the output shaft so as to be able to reciprocate, wear resistance is required. Therefore, it is conceivable to fix a bearing portion, which is a member different from the housing, to the housing, and to support the output shaft so that the output shaft can reciprocate. FIG. 4 shows an example of a configuration in which the bearing portion is fixed to the housing and the output shaft is supported by the bearing portion.

  As shown in FIG. 4, a concave portion 53 is formed in the bearing portion 52 fixed to the housing 51, and the output shaft 60 is inserted and supported by the bottom wall 54 of the concave portion 53. Further, when the stopper 61 provided on the output shaft 60 comes into contact with the bottom wall 54 of the recess 53, the reciprocating motion of the output shaft 60 is restricted. According to such a configuration, since the radial load of the output shaft 60 can be received by the bearing portion 52, the useful life of the actuator 50 can be increased by forming the bearing portion 52 with a material having higher wear resistance than the housing 51, for example. Can be long.

  However, when the bearing portion 52 is fixed to the housing 51 as a separate member in this way, the part for forming the oil discharge path is limited. Therefore, in order to discharge the oil in the housing 51 from the oil discharge path, the oil discharge path must be lengthened. When the oil discharge path becomes longer in this way, the pipe loss in the oil discharge path increases and the oil discharge performance decreases. Further, the gap between the stopper 61 and the side wall 55 of the recess 53 is set as small as possible in order to save space. For this reason, the oil that has flowed in between the stopper 61 and the bottom wall 54 of the recess 53 is difficult to be discharged, and the responsiveness of the actuator 50 is reduced.

  The present invention has been made in view of such a conventional situation, and an object thereof is to suppress the oil discharge path from being lengthened and to improve the discharge performance when oil in the housing is discharged. .

An actuator for solving the above problems has the following configuration. That is, the actuator includes a housing, a bearing portion fixed to the housing, an output shaft that is inserted and supported by the bottom wall of the recess formed in the bearing portion, and reciprocates in conjunction with the rotation of the rotation portion, A stopper provided on the output shaft and restricting the reciprocation of the output shaft by contacting the bottom wall. Further, the actuator is formed on the side wall of the recess to partially enlarge the gap between the side wall and the stopper, and is provided on the bottom wall and opens to the notch to connect the notch and the outside of the housing. And an oil discharge passage communicating therewith.

  According to the said structure, the oil which flowed into the recessed part of the bearing part is discharged | emitted outside through the oil discharge path from the notch formed in the side wall. For this reason, the oil in the housing can be quickly discharged outside without lengthening the oil discharge path. In addition, oil that has flowed in between the stopper and the bottom wall of the recess can also flow into the oil discharge passage through the notch. Furthermore, when the stopper moves together with the output shaft so as to approach the bottom wall of the recess, the oil staying in the recess can be pushed out to the oil discharge passage through the notch. Therefore, it is possible to suppress the oil discharge path from becoming long, and to improve the discharge performance when oil in the housing is discharged.

The fragmentary sectional view showing the structure about one embodiment of an actuator. The enlarged view of the actuator in the embodiment. Sectional drawing which shows the cross-section in the 3-3 line of FIG. The fragmentary sectional view which shows the structure of the conventional actuator.

Hereinafter, an embodiment of a rotation / linear motion conversion actuator will be described.
As shown in FIG. 1, the actuator 10 has a housing 11 and a control unit 12 assembled to the housing 11 as main outline configurations. Inside the housing 11, a cylindrical nut 15 as a rotating portion, a sun shaft 16 as an output shaft provided at the center of the nut 15, and the nut 15 and the sun shaft 16 are disposed. A rotation / linear motion conversion mechanism 14 including a plurality of planetary shafts 18 is provided.

  The nut 15 is rotatably supported by a bearing 13 provided inside the housing 11 on the radially outer side. Inside the housing 11, there are provided a rotor 20 fixed to the nut 15, and a stator 21 disposed facing the rotor 20 on the radially outer side of the nut 15. The rotor 20 and the stator 21 constitute an electric motor.

  A spline 16 a extending along the axial direction is formed on the sun shaft 16 along the entire circumference, and a stopper 17 having an outer diameter larger than that of the sun shaft 16 is fixed. A concave portion 11 a is formed at the end of the housing 11, and a bearing portion 31, which is a member different from the housing 11, is inserted and fixed in the concave portion 11 a. A concave portion 31 a is formed in the bearing portion 31, and the concave portion 31 a is opened inside the housing 11. A spline 34a is formed on the bottom wall 34 of the recess 31a. When the spline 16a of the sunshaft 16 is engaged with the spline 34a, the sunshaft 16 is inserted and supported by the bottom wall 34. The sun shaft 16 is restricted from reciprocating when the stopper 17 abuts against the bottom wall 34 of the recess 31a. Thereby, the sun shaft 16 reciprocates in the axial direction within a predetermined range. A control shaft 41 of a variable valve mechanism is connected to the tip of the sun shaft 16 via a connecting portion 40.

In addition, oil is supplied to the inside of the housing 11, and lubrication in the rotation / linear motion conversion mechanism 14 is performed by this oil.
As shown in FIG. 2, the bearing portion 31 is formed with a plurality of oil discharge passages 35 communicating with the inside and the outside of the housing 11 by passing through the bottom wall 34 of the bearing portion 31 in the axial direction. Yes. A plurality of notches 36 are formed on the side wall 33 of the recess 31 a of the bearing portion 31. The notch 36 is formed from one end to the other end of the side wall 33 of the recess 31 a of the bearing portion 31 in the axial direction of the sun shaft 16. Each oil discharge passage 35 opens into the notch 36. In the housing 11, a portion adjacent to the bearing portion 31 is formed with a notch 11 b that expands the internal space of the housing 11 and communicates with the notch 36 of the bearing portion 31. Here, the cross-sectional shape of the notch 11 b of the housing 11 is the same as the notch 36 of the bearing portion 31.

  As shown in FIG. 3, three oil discharge passages 35 and three notches 36 of the bearing portion 31 are formed in the circumferential direction of the sun shaft 16 at predetermined angular intervals. In FIG. 3, three notches 36 are denoted by reference numerals “36A”, “36B”, and “36C”, respectively. A gap 37 between the side wall 33 of the recess 31a of the bearing 31 and the stopper 17 is partially enlarged by the notches 36A, 36B, and 36C. The notches 36 </ b> A, 36 </ b> B, and 36 </ b> C of the bearing portion 31 are formed at the same position in the circumferential direction of the oil discharge path 35 and the sun shaft 16 so as to communicate with the oil discharge path 35. Although not shown in FIG. 3, three notches 11 b in the housing 11 are also formed in the circumferential direction of the sun shaft 16. The notches 11b are formed at the same positions in the circumferential direction of the notches 36A, 36B, and 36C and the sun shaft 16 so as to communicate with the notches 36A, 36B, and 36C of the bearing portion 31, respectively.

  Here, in order to improve the oil discharging property, it is desirable that the following relationship is satisfied with respect to the shapes of the notches 36 and 11b respectively formed in the bearing portion 31 and the housing 11. That is, with the center axis of the sun shaft 16 as the center, the notches 36A, 36B, and 36C open in the recesses 31a of the bearing portion 31 with lengths corresponding to the angles DA, DB, and DC, respectively. The length from the central axis of the sun shaft 16 to the inner peripheral surface of the side wall 33 of the bearing portion 31 is a length R. A gap between the outer peripheral surface of the stopper 17 and the inner peripheral surface of the side wall 33 of the bearing portion 31 is a length Δd. These values satisfy the following relational expression (1). In the following relational expression (1), “π” is the circumference, and “L” is the length in the axial direction of the notches 36 and 11 b formed in the bearing portion 31 and the housing 11, respectively.

6 × Δd × L <((DA + DB + DC) / 360) × 2 × π × R × L (1)

  Here, the left side of the above equation (1) is a distribution area when the oil flowing into the notches 36 and 11b flows through the gap between the outer peripheral surface of the stopper 17 and the inner peripheral surface of the recesses 31a and 11a. The right side is the opening area of each notch 36, 11b.

Next, the operation of the actuator 10 will be described.
In the actuator 10, a rotational driving force is generated in the rotor 20 by electromagnetically driving the stator 21 by the control unit 12. As a result, the nut 15 rotates, and the planetary shaft 18 revolves around the sun shaft 16 while rotating. The rotation of the sun shaft 16 about its axis is locked by the spline 16 a of the sun shaft 16 and the spline 34 a of the bottom wall 34 of the recess 31 a of the bearing portion 31. For this reason, due to the differential between the planetary shaft 18 and the sun shaft 16 generated by the rotation and revolution of the planetary shaft 18, the sun shaft 16 reciprocates in the axial direction. Thus, in the actuator 10, the sun shaft 16 reciprocates in conjunction with the rotation of the nut 15.

  When the sun shaft 16 reciprocates, the control shaft 41 of the variable valve mechanism moves in the axial direction in conjunction with the movement. By this movement, the variable valve mechanism of the internal combustion engine functions to continuously adjust the valve operating angle (or valve lift amount) of the intake valve provided in each valve system, for example, each cylinder.

  The oil lubricated in the rotation / linear motion converting mechanism 14 of the actuator 10 flows into the recess 31 a of the bearing portion 31. Thus, the oil that has flowed into the recess 31a of the bearing portion 31 flows into the notch 36 in the side wall 33 of the recess 31a. Then, the oil is discharged to the outside through the oil discharge passage 35 from the notch 36 of the recess 31 a in the bearing portion 31. In this way, the oil that has flowed into the recess 31a of the bearing portion 31 quickly flows into the oil discharge passage 35 through the notch 36 and is further discharged to the outside, so that the oil dischargeability can be improved. In particular, the opening area of the notches 36 and 11b and the gap from the outer peripheral surface of the stopper 17 to the inner peripheral surface of the side wall 33 of the bearing portion 31 are values satisfying the relational expression (1). As a result, the oil easily flows into the notches 36 and 11b from the gap between the outer peripheral surface of the stopper 17 and the inner peripheral surface of the side wall 33 of the bearing portion 31 and the inner peripheral surface of the recess 11a of the housing 11. ing.

  For this reason, for example, in the axial direction of the sun shaft 16, the oil discharge path is formed through the housing 11 and the bearing portion 31, and the oil discharge path is communicated with the interior of each of the recesses 31 a and 11 a. The oil in the housing 11 can be discharged to the outside without making the oil discharge path 35 long, such as communicating with the path.

  The notch 36 is formed from one end to the other end of the side wall 33 of the recess 31 a of the bearing portion 31 in the axial direction of the sun shaft 16. For this reason, regardless of the position of the stopper 17 in the axial direction of the sun shaft 16, the state between the stopper 17 and the bottom wall 34 of the recess 31 a communicates with the notch 36 of the side wall 33 of the bearing portion 31. It has become. As a result, the oil that flows between the stopper 17 and the bottom wall 34 flows into the oil discharge path 35 through the notch 36.

  Further, the stopper 17 moves so as to approach the bottom wall 34 of the recess 31 a of the bearing portion 31 as the sun shaft 16 reciprocates, so that the oil staying in the recess 31 a is transferred to the oil discharge path 35 through the notch 36. Can be extruded. Therefore, the oil dischargeability can be improved by pushing the oil into the notch 36 by the stopper 17.

According to the actuator 10 described above, the following effects can be obtained.
(1) The oil that has flowed into the recess 31 a of the bearing portion 31 is discharged to the outside through the oil discharge passage 35 from the notch 36 formed in the side wall 33. Thereby, it can suppress that the oil discharge path 35 becomes long, and can improve the discharge | emission property at the time of discharging the oil in the housing 11 collectively.

The above-described embodiment can be modified as follows.
The notch 36 (36A, 36B, 36C) of the bearing portion 31, the oil discharge passage 35, and the notch 11b of the housing 11 are shifted from each other in the circumferential direction of the sun shaft 16 as long as they are within a range where they are in communication with each other. It may be formed at a different position.

  The number of the notches 36 of the bearing portion 31 may be two or less or four or more in the circumferential direction of the sun shaft 16. In short, the number of the cutouts 36 can be freely set as long as the cutouts 36 are partially formed in the circumferential direction of the sun shaft 16 and can obtain an effect of improving the oil dischargeability in the housing 11. . The number of the oil discharge passages 35 communicating with the notches 36 may be two or less or four or more in the circumferential direction of the sun shaft 16 according to the number of the notches 36.

The notch 36 may be formed in a part of a range from one end to the other end of the side wall 33 of the concave portion 31 a of the bearing portion 31 in the axial direction of the sun shaft 16.
-The notch 11b of the housing 11 can be omitted. Even in such a modification, the oil in the housing 11 can be discharged by the notch 36 in the side wall 33 of the recess 31 a of the bearing portion 31.

  DESCRIPTION OF SYMBOLS 10 ... Actuator, 11 ... Housing, 15 ... Nut, 16 ... Sunshaft, 17 ... Stopper, 31 ... Bearing part, 31a ... Recessed part, 33 ... Side wall, 34 ... Bottom wall, 35 ... Oil discharge path, 36, 36A, 36B , 36C ... notches, 37 ... gaps.

Claims (1)

A housing;
A bearing portion fixed to the housing;
An output shaft that is inserted into and supported by the bottom wall of the recess formed in the bearing portion and reciprocates in conjunction with the rotation of the rotating portion;
A stopper that is provided on the output shaft and regulates reciprocation of the output shaft by contacting the bottom wall;
A notch formed on the side wall of the recess to partially enlarge the gap between the side wall and the stopper;
An actuator provided on the bottom wall , and comprising an oil discharge passage that opens into the cutout and communicates the cutout with the outside of the housing.