The disclosure of Japanese Patent Application No. 2015-043232 filed on Mar. 5, 2015 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field
This disclosure relates to a one-way clutch that is used as a brake mechanism for fixing either one of two rotational members that rotate relative to each other and thereby allowing rotation of the either one of the two rotational members in one rotational direction while restricting rotation thereof in the other rotational direction.
2. Description of Related Art
A one-way clutch can function as a brake mechanism for unrotatably fixing either one of two rotational members of the one-way clutch that rotate relative to each other and thereby restricting rotation of the either one of the two rotational members in only one direction. For example, a rotational direction of a rotational body, such as an output shaft of an engine or a motor, can be restricted in only one direction by fastening the one rotational member of the one-way clutch to the rotational body and fixing the other rotational member to a fixing body, such as an engine block or a transmission housing. The one rotational member of the one-way clutch and the rotational body are typically fastened by a bolt.
The disclosure related to a structure of the one-way clutch as described above and an assembling method thereof is described in Japanese Patent No. 5288051. The one-way clutch described in this Japanese Patent No. 5288051 is assembled to the engine block by using a jig that has a male screw section and a pin-shaped section for positioning. More specifically, first, an inner race, an outer race, and an engagement member that constitute the one-way clutch are integrally and temporarily assembled by the male screw section of the jig. A flywheel is positioned with respect to the temporarily assembled one-way clutch by the pin-shaped section of the jig. Then, these one-way clutch and flywheel are fixed to a flange that is provided at a tip of a crankshaft by the bolt.
As in the configuration described in above Japanese Patent No. 5288051, it is common that the one-way clutch is fixed to the flange of the rotational body that is formed with a screw hole by the bolt, for example. Torque can reliably be transmitted between the one-way clutch and the rotational body when the one-way clutch is fixed by the bolt. However, when the bolt is used to fasten the one-way clutch and the rotational body, a phase of a bolt hole, which is formed in the one-way clutch, and a phase of the screw hole, which is formed in the flange of the rotational body, have to be coincided with each other during assembly. When the bolt is fastened in a state where the phase of the bolt hole and the phase of the screw hole are not coincided with each other, the screw hole and a screw head of the bolt possibly interfere with each other, and thus an appropriate bolt fastening force cannot possibly be obtained.
In particular, in the case where the one-way clutch is used as the brake mechanism as described above, relative rotation between the two rotational members of the one-way clutch is limited to the one direction. Thus, there is a case where the phase of the bolt hole and the phase of the screw hole are not easily coincided with each other. It should be noted that the phase of the bolt hole and the phase of the screw hole can easily be coincided with each other by increasing a radius of the bolt hole. However, an area of a seat surface that receives an axial force from the bolt during fastening is reduced by an increase in the radius of the bolt hole. Thus, also in this case, the appropriate bolt fastening force cannot possibly be obtained.
This disclosure provides a one-way clutch that can secure favorable assemblability of the one-way clutch with a rotational body and fix the one-way clutch and the rotational body with an appropriate bolt fastening force when the one-way clutch is used as a brake mechanism.
A one-way clutch related to the present disclosure includes a first rotational member, a second rotational member, and a first rotational body. The second rotational member is configured to rotate relative to the first rotational member. The second rotational member has plural first through holes in which bolts are inserted. The first rotational member and the second rotational member are configured to be engaged only in a specified rotational direction. The second rotational member is configured to restrict rotation in the specified rotational direction by unrotatably fixing the first rotational member. The first rotational body has plural screw holes to which the bolts are fitted. The first rotational body and the second rotational member are configured to restrict rotation of the first rotational body in the specified rotational direction by being fastened by the bolts to each other. A dimension of the first through hole in a circumferential direction of a pitch circle in which the first through hole is arranged is larger than a dimension of the first through hole in a radial direction of the pitch circle. The first through hole has a first region and a second region. The first region and the second region are obtained by dividing the first through hole into two regions in the circumferential direction. The first region is located ahead of the second region in a rotatable direction of the second rotational member. The bolts are inserted such that the each of the bolts is located in the first region of the first through hole, and the second rotational member and the first rotational body are fastened by the bolts.
According to this one-way clutch, the first rotational member is unrotatably fixed. Accordingly, this one-way clutch is used as the brake mechanism that restricts the rotation of the second rotational member in the specified rotational direction. In addition, the second rotational member of the one-way clutch as described above is fastened to the first rotational body by the bolt. In this way, the one-way clutch functions as the brake mechanism that restricts the rotation of the first rotational body in the specified rotational direction. The first rotational body is formed with the screw hole to which the fastening bolt is fitted, and the second rotational member is formed with the first through hole in which the fastening bolt is inserted. Accordingly, the second rotational member and the first rotational body are fastened by inserting the bolt in the first through hole of the second rotational member and fitting the bolt to the screw hole of the first rotational body. In this case, the first through hole in this disclosure is the long hole that has the larger hole dimension in the circumferential direction of the pitch circle, in which the first through hole is arranged, than the hole dimension in the radial direction of the pitch circle. Thus, the phase of the first through hole of the second rotational member can easily be coincided with the phase of the screw hole of the first rotational body in the circumferential direction of the pitch circle. Therefore, assemblability of the one-way clutch with the first rotational body can be improved.
The one-way clutch may further include a second rotational body. The second rotational body has plural second through holes. The second through holes are circular bolt holes in which the bolts are inserted. A dimension of the first through hole in the radial direction is substantially equal to a diameter of the second through hole. The second rotational member is arranged between the first rotational body and the second rotational body, and, together with the second rotational member, the second rotational body is fastened to the first rotational body by the bolt.
The one-way clutch may further include a fixing body, a fixing plate fastened to the fixing body. The first rotational member is unrotatably fixed via the fixing plate. The second rotational member and the fixing plate each have a mark. When positions of the marks of the second rotational member and the fixing plate are coincided with each other, a phase of the second rotational member is coincided with a phase of the fixing plate in the circumferential direction such that each of the bolts is located in the first region.
Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
Next, this disclosure will specifically be described with reference to the drawings. One example of a vehicle Ve that uses a one-way clutch as a target of this disclosure is shown in
The power split mechanism 4 is constructed of a planetary gear unit that has a sun gear 6, a ring gear 7, and a carrier 8, for example. In this example shown in
The first motor 2 is coupled to the sun gear 6 of the above planetary gear unit. More specifically, the first motor 2 is arranged on an opposite side of the engine 1 with the power split mechanism 4 being interposed therebetween, and a rotor 2a of the first motor 2 is coupled to the sun gear 6. The ring gear 7 as an internal gear is coaxially arranged with respect to this sun gear 6. A pinion gear that meshes with these sun gear 6 and ring gear 7 is held by the carrier 8 in a manner to be able to rotate and revolve. An input shaft 4a of this power split mechanism 4 is coupled to the carrier 8. The input shaft 4a is coupled to the output shaft 1a of the engine 1 via a damper mechanism 9, a flywheel 10, and a one-way clutch 11.
The damper mechanism 9 is used to suppress a fluctuation in torque of the output shaft 1a and a torsional vibration caused by the fluctuation in the torque, and is assembled to integrally rotate with the flywheel 10, for example.
In addition, the one-way clutch 11 is arranged between a housing 12 and an engine block 1b of the engine 1. The housing 12 accommodates a transmission mechanism for constituting a drive system of this vehicle Ve that includes this one-way clutch 11, the first motor 2, the second motor 3, and the like. The housing 12 and the engine block 1b are integrally fixed by fastening a bolt by interposing a fixing plate 13 of the one-way clutch 11, which will be described below, therebetween.
The one-way clutch 11 is constructed of an inner race 11a and an outer race 11b that rotate relative to each other, the fixing plate 13, and an engagement mechanism (for example, a ratchet mechanism 16, which will be described below). The inner race (a first rotational member) 11a and the fixing plate 13 are fastened by splines or serration, for example. The fixing plate 13 is fixed to the housing 12 and the engine block 1b (a fixing body), which are described above. The outer race (a second rotational member) 11b is attached to the above output shaft 1a (a first rotational body). The engagement mechanism is engaged only in either one of the rotational directions, so as to be able to transmit the torque between the inner race 11a and the outer race 11b. Here, the fixing body is a member that is fixed to the vehicle. Alternatively, the fixing body is a member that is not displaced with respect to the vehicle.
This one-way clutch 11 functions as a brake mechanism that restricts rotation in only one direction by fixing the one inner race 11a via the fixing plate 13 as described above. More specifically, the one-way clutch 11 is configured to be disengaged when the output shaft 1a makes positive rotation and be engaged to stop the rotation when the torque in a direction to cause reverse rotation of the output shaft 1a acts on the output shaft 1a. The positive rotation is rotation in a rotational direction of a crankshaft (the output shaft 1a) when the engine 1 is operated for combustion, and the reverse rotation is rotation in a reverse direction of the positive rotation.
The vehicle Ve, which is configured as described above, is controlled such that each of the drive power sources of the engine 1, the first motor 2, and the second motor 3 is effectively used to achieve favorable energy efficiency or fuel economy and that requested drive power can be satisfied. In particular, in the case where the high drive power is requested during an EV travel in which the operation of the engine 1 is stopped and the vehicle Ve travels by output of the motors only, the EV travel by the output of both of the first motor 2 and the second motor 3 is conducted. More specifically, the first motor 2 is controlled to rotate in a reverse rotational direction and output the torque as the motor, and the second motor 3 is controlled to rotate in a positive rotational direction and output the torque as the motor. In this case, the one-way clutch 11 is engaged because the torque in the reverse rotational direction acts on the output shaft 1a of the engine 1. As a result, the vehicle Ve can efficiently make the EV travel at high output by the output of both of the first motor 2 and the second motor 3 in a state where the rotation of the output shaft 1a of the engine 1 and the rotation of the carrier 8 of the power split mechanism 4 are stopped. In addition, in this vehicle Ve, by using the one-way clutch 11 as described above, the rotation of the output shaft 1a and the rotation of the carrier 8 are easily stopped and can be thus fixed without executing any special operation or control during the EV travel by the output of both of the first motor 2 and the second motor 3.
The fixing plate 13 is attached to the inner race 11a of the one-way clutch 11. As shown in
The one-way clutch 11 is provided with the engagement mechanism between the inner race 11a and the outer race 11b. As one example, the engagement mechanism is constructed of the ratchet mechanism 16 as shown in
As described above, this one-way clutch 11 is arranged between the engine 1 and the housing 12 and is assembled to the engine 1. More specifically, the inner race 11a of the one-way clutch 11 is fixed to the engine block 1b via the fixing plate 13. In addition, the outer race 11b is attached to rotate integrally with the flange 1c of the output shaft la. The outer race 11b and the flange 1c are fastened by the bolt. Accordingly, the flange 1c is formed with plural screw holes 1d to which fastening bolts are fitted. In the example shown in
As shown in
Furthermore, this one-way clutch 11 is configured to be able to fasten the outer race 11b and the flange 1c by the bolt with an appropriate fastening force while avoiding interference between the bolt hole 11c and a screw head of the bolt when the outer race 11b is fastened to the flange 1c by the bolt. Accordingly, in this one-way clutch 11, the outer race 11b and the fixing plate 13 are each provided with a mark that is used to set a rotational position of the outer race 11b during assembly at an optimum position. In the example shown in
Positions of the above marks M1 and mark M2 are set such that the fastening bolt is located in a first region A1 of regions A1, A2 that are formed by dividing the bolt hole 11c into two in the circumferential direction of the pitch circle PC when either one of the marks M1 is coincided with the mark M2 during the assembly of the one-way clutch 11. That is, the positions of the marks M1 and the mark M2 are set such that a phase of the first region of the bolt hole 11c and the phase of the screw hole 1d of the flange 1c correspond to each other in the circumferential direction of the pitch circle
PC when the marks M1 is coincided with the mark M2. The first region A1 is a region that is located on a side where the outer race 11b can rotate (in a direction indicated by the arrow R in
It should be noted that, as will be described below, the output shaft la and the flywheel 10 are fastened by the bolt with the outer race 11b being interposed therebetween in this one-way clutch 11. In this case, the flywheel 10 is formed with a bolt hole 10a in a circular shape in which the fastening bolt is inserted, that is, in a normal shape. Accordingly, even when the bolt hole 11c of the outer race 11b is the long hole as described above, the outer race 11b and the flywheel 10 can appropriately be fastened to the flange 1c of the output shaft 1a by the bolt with a fastening force equivalent to the fastening force needed for normal fastening of the bolt for which the long hole is not used.
An assembling procedure of the one-way clutch 11 is shown in
First, the fixing plate 13 of the one-way clutch 11 is positioned by the knock pins 14 and attached to the engine block 1b (
The one-way clutch 11 is assembled to the fixing plate 13 that is attached to the engine block 1b (
The outer race 11b of the one-way clutch 11, which has been assembled to the fixing plate 13, is rotated in the rotational direction of the arrow R, and the mark M1 is thereby coincided with the mark M2 (
The flywheel 10 is assembled to the one-way clutch 11 that is in the state where the mark M1 is coincided with the mark M2 as described above (
When the flywheel 10 is assembled to the one-way clutch 11 in a state where the phase of the bolt hole 10a is coincided with the phases of the screw hole 1d and the bolt hole 11c as described above, the flywheel 10 and the one-way clutch 11 are fastened to the output shaft 1a by a bolt 17 (
An operational effect of the one-way clutch according to the disclosure will hereinafter be described. According to this one-way clutch, the one-way clutch is constructed of the first rotational member and the second rotational member that make relative rotation to each other as well as the engagement mechanism for engaging the first rotational member with the second rotational member only in a specified rotational direction like the ratchet mechanism, for example. The first rotational member of the one-way clutch is attached to the engine block, the housing of a transmission, and the like, for example and is unrotatably fixed. Accordingly, the one-way clutch in this disclosure is used as the brake mechanism that restricts rotation of the second rotational member in the specified rotational direction. In addition, the second rotational member of the one-way clutch as described above is fastened to the first rotational body, such as the output shaft of the engine or the motor, by the bolt. In this way, the one-way clutch functions as the brake mechanism that restricts rotation of the first rotational body in the specified rotational direction. The first rotational body is formed with the screw hole to which the fastening bolt is fitted, and the second rotational member is formed with the first through hole in which the fastening bolt is inserted. Accordingly, the second rotational member and the first rotational body are fastened by inserting the bolt in the first through hole of the second rotational member and fitting the bolt to the screw hole of the first rotational body. In this case, the first through hole in this disclosure is the long hole that has the larger hole dimension in the circumferential direction of the pitch circle, in which the first through hole is arranged, than the hole dimension in the radial direction of the pitch circle. Thus, the phase of the first through hole of the second rotational member can easily be coincided with the phase of the screw hole of the first rotational body in the circumferential direction of the pitch circle. Therefore, the assemblability of the one-way clutch with the first rotational body can be improved.
Furthermore, in this disclosure, the bolt is inserted in the first through hole, and the second rotational member and the first rotational body are fastened by the bolt such that the bolt is located in the first region in the first through hole that has the long hole shape as described above. The first region is a region that is located on the side where the second rotational member can rotate in the circumferential direction of the pitch circle. Accordingly, even in the case where the screw head of the bolt and the inner surface of the bolt hole interfere with each other during fastening of the bolt, the second rotational member can move so as to escape in the direction to eliminate the interference. Therefore, when the one-way clutch, the rotation of which in the one direction is restricted, is assembled to the rotational body, the interference between the screw head of the bolt and the inner surface of the bolt hole is avoided, and thus these one-way clutch and rotational body can appropriately be fastened by the bolt.
In addition, according to this disclosure, the first rotational body and a second rotational body are fastened by the bolt with the second rotational member of the one-way clutch being interposed therebetween. The second rotational body is formed with a second through hole in the circular shape in which the fastening bolt is inserted, that is, in the normal shape. Accordingly, even when the first through hole of the second rotational member is the long hole, the first rotational body and the second rotational body can appropriately be fastened to the second rotational member of the one-way clutch by the bolt with a fastening force equivalent to the fastening force needed for normal fastening of the bolt for which the long hole is not used.
In addition, the fixing plate is attached to the fixing body, such as the engine block or the housing of the transmission. The first rotational member is unrotatably fixed to the fixing plate when the first rotational member is integrally fastened thereto. In the state where the first rotational member is fastened to the fixing plate, the second rotational member can rotate only in the one rotational direction with respect to the fixing plate and the fixing body. Furthermore, in this disclosure, the mark is added to each of the second rotational member and the fixing plate. Accordingly, when the mark of the second rotational member and the mark of the fixing plate are coincided with each other, the fastening bolt is brought into the state of being located in the first region of a first bolt hole that is formed in the second rotational member. That is, when the marks are coincided with each other, a phase of the first region of the first bolt hole and the phase of the screw hole of the first rotational body are coincided with each other in the circumferential direction of the pitch circle. Therefore, the one-way clutch and the first rotational body can easily be assembled.
It should be noted that, even in the case where the first through hole is displaced to the side where the first through hole interferes with the bolt with respect to the screw hole of the first rotational body due to an error during the assembly, displacement of the phase of the first rotational body, for example, the second rotational member can move so as to escape in the direction to eliminate the interference, as described above, during the fastening of the bolt in the state where the marks are coincided with each other as described above. Therefore, the second rotational member and the first rotational body or the second rotational member, the first rotational body, and the second rotational body can appropriately be fastened by the bolt while avoiding interference between the screw head of the bolt and the inner surface of the first through hole.
Number | Date | Country | Kind |
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2015-043232 | Mar 2015 | JP | national |