JP4318411B2 - Two-way overrunning clutch mechanism - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a two-way overrunning clutch suitable for use in an automobile differential. Specifically, the present invention relates to a two-way overrunning clutch mechanism using a roller and a cam surface that can selectively lock a differential of an automobile.
[0002]
[Background]
A differential is a device that allows both to rotate at different speeds while transmitting power to the drive wheels of an automobile. Various types of differential mechanisms are known which are used to transmit power to the drive axle of an automobile.
[0003]
In the case of a normal differential, when the vehicle is bent, power is transmitted to the differential housing via the pinion gear and the ring gear, but the inner wheel and the outer wheel follow different circular tracks. Therefore, the side gears to which the two axles are respectively connected rotate at different speeds as the spider gear engaged with the side gears rotates. If the friction between the driving wheel and the road surface is sufficient, the power is sufficiently transmitted to the driving wheel through the differential mechanism. However, if the friction with the road surface becomes small or disappears at all, the normal differential mechanism starts to idle, and almost no power is transmitted to the drive wheels. For example, if one tire of the drive wheel rides on a slippery road surface such as a frozen road surface and the other drive wheel is on a dry road surface, only the low friction side wheel will idle, and as a result all the power will be idle. It happens to be transmitted to the wheel that is running. In this case, since no power is transmitted to the wheels on the dry road surface, the vehicle cannot move forward or backward. In such a case, it is necessary to lock the two axles.
[0004]
A mechanism for eliminating the above-mentioned drawbacks of the standard differential mechanism is called a diff lock. A typical differential lock mechanism includes a “dog” clutch or axial gear for locking the two drive axles. However, this type of differential lock mechanism cannot be operated while the vehicle is running. This is because if the gear teeth are engaged during traveling, the gears are easily damaged. Therefore, a device that can instantaneously lock the differential mechanism while traveling is desired.
[0005]
A clutch mechanism having a roller and a cam surface for selectively locking parts of a drive system other than the differential is known. For example, a two-way overrunning clutch described in US Pat. No. 927456 (this reference is regarded as a part of the present specification) assigned to NTN Corporation uses a roller and a cam surface to press the roller. A holding mechanism is provided. The rotation transmission device described in US Pat. No. 5,924,510 (also referred to as a part of this specification), also assigned to NTN Corporation, is housed in a transfer of a four-wheel drive vehicle. A clutch mechanism for selectively transmitting the driving force is provided.
[0006]
It is desirable to use such a device in a differential machine so that the two axles can be locked as required while the vehicle is running.
[0007]
A first object of the present invention is to incorporate a two-way overrunning clutch as disclosed in U.S. Pat. Nos. 5,927,456 and 5,924,510 into a differential of an automobile and operate one of the side gears by operating the clutch. By locking the drive axle to the housing of the differential, the two drive wheels cannot be rotated relative to each other. The clutch can be controlled using an electromagnetic trigger clutch, a hydraulic or pneumatic device, or the like according to the friction state between the wheel and the road surface.
[0008]
Another object of the present invention is to provide a differential mechanism that can be instantaneously locked in accordance with the situation while the automobile is running.
[0009]
SUMMARY OF THE INVENTION
The overrunning clutch mechanism of the present invention has a cylindrical inner peripheral surface, is rotatable about an axis, and has an outer race whose one end is closed by a case end member, and the cylindrical inner peripheral surface through a gap. And an inner race that is coaxial with the cylindrical inner circumference and that is rotatable relative to the outer race about the axis. A plurality of (planar or slightly concave) cam surfaces are formed on the outer peripheral surface. A plurality of rollers are incorporated between the outer race and the inner race in a state where each roller is located at the center of each cam surface, and the diameter of the roller is the center of the cylindrical inner peripheral surface and each cam surface It is set smaller than the distance between the parts. The rollers are held by a cage so as to move simultaneously in the circumferential direction, and the cage can rotate relative to the inner race within a predetermined range about the axis. . A first urging member is supported by the cage, and the roller is held at the center of each cam surface by urging the cage in the circumferential direction by the first urging member. The working disk is connected to the cage so that it can move somewhat axially toward the case end member relative to the cage. In a preferred embodiment, a notch is formed in the outer peripheral edge of the working disk, and the working disk is attached to the retainer by engaging a tab extending in an axial direction from one end of the retainer. It can move in the axial direction, but it cannot be rotated relatively. A second urging member that urges the working disk toward the cage in a direction away from the case end member is incorporated between the working disk and the inner surface of the case end member.
[0010]
The clutch mechanism further includes an actuator for pressing the operating disk against the case end member against the second urging member, and selectively actuates the actuator to friction the operating disk against the case end member. By contacting, the rotation of the outer race and the case end member is transmitted to the operating disk and the cage, and the cage is rotated against the first urging member, thereby rotating the roller on the cam surface. By moving and interposing between the inner race and the outer race, the inner race and the outer race can be prevented from rotating relatively.
[0011]
[Preferred embodiment]
The following description of the preferred embodiment is not intended to limit the invention to this embodiment, but is intended to enable one of ordinary skill in the art to practice the invention.
[0012]
In FIG. 1-3, the whole overrunning clutch mechanism of this invention is shown by 10. The clutch mechanism 10 has a cylindrical inner surface 14 and an outer race 12 that is rotatable about an axis 16. A case end 18 is formed at one end of the outer race 12. The clutch mechanism 10 further has an inner race 20. The inner race has an outer peripheral surface 22 disposed coaxially with the cylindrical inner surface 14 of the outer race 12. A gap 24 is formed between the inner race 20 and the outer race 12 by the cylindrical inner surface 13 of the outer race 12 and the outer peripheral surface 22 of the inner race 20. The inner race 20 also rotates about the axis 16. The outer race 12 includes means such as a flange 26 for attaching the clutch mechanism 10 to the differential housing 28. As a material of the roller 34, the inner race 20, and the outer race 12, steel is preferable. Since high contact Hertz stress is applied to the roller 34, the inner peripheral surface 14 of the outer race 12, and the outer peripheral surface 22 of the inner race 20, the inner peripheral surface 14 and the outer peripheral surface 22 should be ground and then ground. desirable.
[0013]
A plurality of slopes, that is, cam surfaces are formed on the outer peripheral surface 22 of the inner race 20 at intervals. The plurality of rolling elements 34 are fitted between the outer race 12 and the inner race 20 in a state where each of the rolling elements 34 is supported at the center of each cam surface. The diameter of the rolling element 34 is set to a value smaller than the gap 24 between the central portions of the cam surfaces of the cylindrical inner surface 14 and the outer peripheral surface 22 and larger than the gap between the cylindrical inner surface 14 and both ends of the cam surfaces. The rolling elements 34 are held by a holder 36 so as to move in the circumferential direction all at once. The retainer 36 can rotate around the axis 16 within a predetermined range with respect to the inner race 20. The retainer 36 includes a tab 38 that extends in the axial direction toward the inner surface 40 of the case end 18. The end of the tab 38 is adjacent to the inner surface 40 of the case end 18.
[0014]
The roller is urged toward the central portion of each cam surface by a first urging member 81 attached to the cage 36. An operating disk 46 is provided between the retainer 36 and the inner surface 40 of the case end 18. The working disk 46 has an outer peripheral edge 48 and an inner peripheral edge 50, and a notch 54 is formed in the outer peripheral edge 48. The notch 54 is fitted with a retainer tab 38 so that the working disk 46 can move axially with respect to the retainer 36 but cannot rotate. A second urging member 56 is provided between the working disk 46 and the inner surface 40 of the case end 18 and urges the working disk 46 toward the retainer 36 in a direction away from the case end 18. The second urging member 56 is preferably a wave spring.
[0015]
The first biasing member in the preferred embodiment is supported by the retainer 36 and engages with the inner race 20, each rolling element 34 is located at the center of each cam surface, and the outer race 12 and the inner race 20 are It is a spring which holds the retainer 36 at a position where it can be relatively rotated freely. The spring includes a plurality of small tongues (not shown) that extend radially inward or outward and engage small notches (not shown) formed in the hub 72 of the inner race 20. The pressing force of this spring needs to be adjusted accurately. That is, the first urging member is required to have a pressing force that can easily move the retainer 36 and the rolling element 34 to the neutral position in a state in which the clutch mechanism 10 is disengaged. It should not be greater than the friction force generated between the disk 46 and the case end 18 when it is pressed against it. Otherwise, the clutch mechanism 10 cannot be operated.
[0016]
As shown in FIG. 4, a groove for improving the flow of the lubricant is formed on one surface of the working disk 46 when the temperature is low and the viscosity of the lubricant is so high as to adversely affect the operation of the clutch. . Examples of such a groove include a radial groove, a circumferential groove, and a left-handed and right-handed spiral. The spiral groove serves to push out a relatively viscous lubricant from the interface of the relatively rotating part by causing the lubricant to flow in a helical manner when the part is relatively rotating.
[0017]
The clutch mechanism 10 includes an actuator 58 for pressing the operating disk 46 against the case end 18 against the force of the second urging member 56. Since the working disk 46 can move in the axial direction with respect to the retainer 36, when the suction force of the actuator 58 exceeds the force of the second pressing member 56, the working disk 46 moves toward the inner surface 40 of the case end 18, Pressed against the inner surface 40. When the working disk 46 is pressed against the inner surface 40 of the case end 18, the rotation of the outer race 12 and the case end 18 is transmitted to the working disk 46 by the frictional force between them. Since the retainer tab 38 is engaged with the working disk 46, the rotation of the outer race 12 and the case end 18 is transmitted to the retainer 36 via the working disk 46.
[0018]
When the retainer 36 starts to rotate relative to the inner race 20 in this way, the rolling element 34 starts to move from the center portion of the cam surface toward one end portion. Since the width of the gap 24 at the end of the cam surface is smaller than the diameter of the rolling element 34, when the rolling element 34 starts to move from the central part of the cam surface toward one end, the outer peripheral surface 22 of the inner race and the outer race The inner race 20 and the outer race 12 are locked and rotate integrally. In a state where the rolling element 34 is caught between the inner race 12 and the outer race 20, each cam surface of the inner race 20 and the tangent line of the inner peripheral surface 14 at the contact point between the inner peripheral surface 14 of the outer race 12 and the rolling element. The cam surface is formed so as to form a predetermined angle. In order to allow the rolling elements to be firmly engaged between the inner peripheral surface 14 of the outer race 20 and the outer peripheral surface 22 of the inner race 20, the angle is preferably about 4 ° to about 10 °. When this angle is less than the above range, the contact Hertz stress between the rolling elements and the inner and outer races becomes too high, and the rolling elements 34 are crushed or Brinell indentations are likely to occur on the peripheral surfaces of the inner and outer races 12 and 20. When this angle exceeds the above range, the outer race 12 tends to slip out from the inner peripheral surface 14 of the outer race 12 and the outer peripheral surface 22 of the inner race 20. The shape of the cam surface and the interaction between the cam surface and the rolling element are described in detail in US Pat. Nos. 5,927,456 and 5,924,510, both assigned to NTN Corporation.
[0019]
The actuator 58 in the preferred embodiment is an electromagnetic coil 60 housed in a housing 62 attached to the outer surface of a fixed axle housing (not shown). The case end 18 is formed with a plurality of circumferential slots 66 penetrating the case end 18 in the axial direction and separated from each other in the circumferential direction. When the electromagnetic coil 60 is energized, a magnetic flux is generated, and the magnetic flux passes through the working disk 46 from the slot 66. When the magnetic flux passes through the working disk 46, the working disk 46 is pulled toward the inner surface 40 of the case end 18 by the magnetic force. When the magnetic force of the electromagnetic coil 60 exceeds the force of the second urging member 56, the operating disk 46 actually starts moving toward the inner surface of the case end 18.
[0020]
As the form of the actuator 58, the electromagnetic coil 60 is preferable, but another type of actuator may be used. For example, as means for moving the operating disk 46, hydraulic means, pneumatic means, etc. may be used in addition to the electromagnetic means. Since the actuator 58 of the present invention can be directly attached to the fixed axle housing of the drive mechanism, the differential of the present invention can be mounted on an existing axle support. For this reason, the cost of replacement can be suppressed.
[0021]
When the actuator 58 is de-energized, the force for attracting the working disk 46 is lost, so the working disk 46 is pulled away from the inner surface of the case end 18 by the second urging member 56, and there is no friction between them. The rotational force is no longer transmitted to the disk 46. In this way, since the rotational force that separates the cage 36 and the roller 34 from the neutral position is eliminated, the cage 36 is returned to the neutral position by the first biasing member 81, and the roller 34 is returned to the position of the center portion of the cam surface. 10 is released, and the outer race 12 can rotate relative to the inner race 20 again.
[0022]
The working disk 46 of the preferred embodiment is provided with an annular step 82 facing the inner surface of the case end 18 along the inner peripheral edge 50. The second urging member 56 is inserted into the recess formed by the stepped portion, and the second urging member is compressed in the state where the operating disk 46 is pressed against the inner surface 40 of the case end 18, so that It comes to fit completely. The second urging member 56 is inserted into the annular step portion 82 of the operating disk 46, and is compressed when the magnetic force of the electromagnetic coil 60 exceeds the force of the second urging member 56, and is completely accommodated in the annular step portion 82. Wave springs are preferred.
[0023]
The housing 62 of the electromagnetic coil 60 is preferably attached to a fixed axle support and connected to the case end 18 via a bearing 68. As the bearing 68, a ball bearing, a roller bearing, a journal bearing, or the like can be used. Through the bearing 68, the electromagnetic coil 60 and the housing 62 can be fixed to the axle housing. Since the electromagnetic coil 60 is stationary, the wiring is simpler than the electrical wiring for the rotating body. Other types of bearings such as journal bearings may be used instead of the illustrated bearings. Any device that allows relative rotation between the outer surfaces of the housing 62 and the case end 18 may be used.
[0024]
As shown in FIGS. 4 and 5, in the preferred embodiment, a plurality of notches 70 are formed along the inner periphery 50 of the working disk 46. The inner race 20 has a hub 72 adjacent to the outer peripheral surface 22, and the hub 72 is formed with a stepped portion 74 that extends radially outward and axially outward. The step portion 74 extends in the axial direction toward the inner surface 40 of the case end 18, and a gap 76 is formed between the step portion 74 and the inner surface 40 of the case end 18. The working disk 46 is sized so that the inner peripheral edge is positioned in the gap 76 and the stepped portion 74 is engaged with the notch 70 in a state where the working disk 46 is pressed against the retainer 36. Yes. Therefore, in this state, since the operation disk 46 cannot rotate relative to the hub 72 of the inner race 20 due to the engagement between the stepped portion 74 and the notch 70, the operation disk 46 rotates and the clutch 10 is locked. It can be surely prevented from locking when in trouble. When the stepped portion 74 and the notch 70 are not present, for example, when the rotational speed of the outer race 12 is increased while the viscosity of the oil in the clutch 10 is high, the actuator 58 attracts the operating disk 46 to the inner surface 40 of the case end 18. Even without this, there is a possibility that the working disk will rotate due to friction of oil. However, in the present invention, while the stepped portion 74 of the hub 72 is engaged with the notch 70 of the working disk 46, the working disk 46 cannot rotate, and therefore the clutch 10 cannot be locked.
[0025]
When the electromagnetic coil 60 is energized, the operating disk 46 starts to move toward the case end 18, and immediately before the operation disk 46 contacts the inner surface 40 of the case end 18, a step 74 is formed from the notch 70 formed on the inner peripheral edge of the operating disk 46. Exit. Therefore, the operating disk 46 can freely rotate in the space 76 between the stepped portion 74 and the inner surface 40 of the case end 18 so that the clutch 10 can be locked. The stepped portion 74 is preferably formed on the hub 72 of the inner race 20, but may be formed on a ring 78 that is press-fitted to the hub 72 of the inner race 20.
[0026]
In the preferred embodiment, the retainer tab 38 is formed directly on the retainer 36. As shown in FIGS. 2 and 3, the operating spider 80 may be provided so as to rotate integrally with the cage 36. The first urging member 81 holds the retainer 36 in a neutral position with respect to the inner race 20. A tab 38 extending from the actuation spider 80 engages a notch 54 formed in the outer peripheral edge 48 of the actuation disk 46.
[0027]
This clutch mechanism can be used to lock two axles by using it in a differential of an automobile. As shown in FIGS. 6 and 7, the differential has a housing 102 in which an input ring gear (not shown) is formed on the outer periphery 104. Rotational motion from the drive system of the vehicle is transmitted to the housing 102 via the ring gear. The housing 102 incorporates first and second side gears 106 and 108 that are respectively connected to two axles (not shown) of the vehicle. Two or more spider gears 110 mesh with the first and second side gears 106, 108 within the housing 102.
[0028]
Since the two axles rotate at the same speed when the vehicle is traveling straight, the housing 102 and the axle are rotated at the same speed by the power transmitted to the housing 102 via the ring gear. For this reason, the side gears 106 and 108 and the spider gear 110 do not rotate relatively. When the vehicle is bent, the wheels move on circular tracks having different sizes, so that a rotational speed difference is generated between the two axles. For this reason, a rotational speed difference also occurs between the side gears 106 and 108, but the two axles are connected to each other via the spider gear 110, so that the torque is distributed in proportion to the speed of each axle.
[0029]
The clutch mechanism 10 is incorporated in the housing 102 so that the axle can be locked by locking the first side gear 106 to the housing 102 of the differential. As shown in FIG. 7, the second side gear 108 is rotatably incorporated on the second end 114 side in the housing 102. That is, the second side gear 108 cannot move in the axial direction with respect to the housing 102 but can rotate relative to the housing 102. The outer race of the clutch 10 is fixed to the first end 112 side of the housing 102.
[0030]
As shown in the figure, the clutch mechanism 10 and the housing 102 of the differential are connected by fixing the flanges 116 and 117 with mechanical fixing means. However, instead of using the mechanical fixing means, splines are formed on the outer peripheral surface of the outer race 12 and the inner peripheral surface 122 of the housing 102 on the first end 112 side, so that the clutch 10 is connected to the first end 112 of the housing 102. Both may be fixed by press-fitting into the inner periphery 122 on the side.
[0031]
The first side gear 106 is fixed to the inner race 20 of the clutch mechanism 10. In the preferred embodiment, a hole 124 is formed at the center of the inner race 20, and the outer periphery 126 of the first side gear 106 is fixed to the hole 124 of the inner race 20 by press fitting or spline. Alternatively, a center hole is formed in the first side gear 106, a spline is formed in both the center hole and the center hole 124 of the inner race 20, and a spline is also formed on the outer periphery of the first axle connected to the first side gear. If the first side gear and the inner race are connected via the first axle by meshing these splines, the relative rotation of the inner race 20 and the first side gear can be prevented more reliably. In any of the above embodiments, the first side gear 106 and the inner race 20 are fixed to each other and are functionally integrated.
[0032]
The spider gear 110 is incorporated into the housing 102 and rotates about the second axis 128, ie, the axis of the shaft 129 attached to the housing 102. The first and second side gears 106 and 108 rotate around a second axis that is orthogonal to the first axis and coincides with the axes of the first and second axles. Each spider gear meshes with both the first and second side gears 106,108.
[0033]
When the clutch mechanism 10 is disengaged, the inner race 20 and the outer race 12 can rotate relative to each other, so that the first side gear 106 and the first axle 109 can also rotate relative to the housing 102. When the vehicle is bent, for example, there is a difference in rotational speed between the two axles. However, since the two axles are connected to each other via the spider gear 110, the torque is distributed in proportion to the speed of each axle. The When the road surface friction coefficient is low (wet road surface, snowy road, frozen road, etc.), one of the drive wheels may idle, and torque may not be transmitted to the other drive wheel due to the action of the differential. When this happens, it becomes difficult for the vehicle to climb uphill that is not so steep.
[0034]
In such a case, when the clutch 10 is locked, the first axle, the first side gear 106, the inner race 20, the outer race 12, and the housing 102 are fixed to each other and cannot be rotated relative to each other. Since the first side gear 106 is fixed to the housing 102, the spider gear 110 meshing with the first side gear 106 cannot rotate about the first axis 128. For this reason, the second side gear 108 meshed with the spider gear 110 cannot rotate relative to the housing 102. In short, when the clutch mechanism 10 is locked, the first and second side gears 106 and 108 and the first and second axles connected thereto are fixed to each other, and torque is applied to the first and second axles. Are transmitted equally and the two cannot rotate relative to each other.
[0035]
Although only one preferred embodiment has been described above, those skilled in the art will be able to make various changes and improvements from the above description, the accompanying drawings, and the claims without departing from the scope of the invention as defined by the claims. It is. The terms used in the above description of the invention should be interpreted in light of the entire specification, and are not intended to limit the invention.
[Brief description of the drawings]
1 is a perspective view of an overrunning clutch of the present invention. FIG. 2 is a sectional side view of the overrunning clutch of FIG. 1. FIG. 3 is a partial detail view of the overrunning clutch of FIG. FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. 1. FIG. 6 is a cross-sectional view of the differential housing with an overrunning clutch according to the present invention. FIG. 7 is a sectional side view of the differential housing of FIG.

Claims (7)

An inner race is incorporated inside an outer race that is closed at one end by a case end, and is supported in a relatively rotatable manner on the outer circumference of the inner race. A plurality of cam surfaces that are large at the center and have small gaps at both ends are provided at intervals in the circumferential direction, and rollers are incorporated between each cam surface and the cylindrical inner surface, and each roller is disposed between the outer race and the inner race. The cage is held by a built-in cage, and the cage is held in a neutral position where each roller is arranged at the center of the cam surface by a first biasing member supported by the cage and engaged with the inner race. An operation disk is installed between the inner surface of the case end and the end surface of the cage facing the inner surface, and the tabs provided on the end surface of the cage are engaged with the notches formed on the outer peripheral edge of the operation disk. Disc holder And prevent rotation against, and to freely move in the axial direction, and biased toward the retainer the actuation disk by the second biasing member incorporated between the inner surface of the actuation disk and the case end, said actuation disk The inner race has a hub near the outer peripheral surface, and the hub extends radially outward and forms a step extending axially toward the inner surface of the case end. A gap is provided between the step portion and the inner surface of the case end, and the step portion engages with the notch in a state where the operation disc is pressed against the cage, so that the operation disc is relative to the hub and the inner race. While preventing the rotation, and in a state where the working disk is in contact with the inner surface of the case end, the stepped part is pulled out from the notch, and the working disk is relative to the hub and the inner race. Set the width of the actuation disk for rotation, outside the casing end, is accommodated in the housing, two-way overrunning clutch mechanism provided an electromagnetic coil for attracting the actuation disk case end by energization.   The two-way over of claim 1, wherein the case end and the outer race can be rotated relative to the housing by connecting the housing of the electromagnetic coil to the case end via a bearing. Running clutch mechanism. The two-way overrunning clutch mechanism according to claim 1 or 2 , wherein the step portion is formed in a collar, and the collar has an inner diameter smaller than the outer diameter of the hub and is press-fitted to the outer periphery of the hub . The two-way overrunning clutch mechanism according to any one of claims 1 to 3 , wherein the first urging member includes a spring . A concave portion is formed on the axial surface of the working disk, the second urging member is a wave spring fitted in the concave portion, and the wave spring is in contact with the inner surface of the case end. The two-way overrunning clutch mechanism according to any one of claims 1 to 4, wherein the two-way overrunning clutch mechanism is compressed and fits in the recess . The two-way overrunning clutch mechanism according to any one of claims 1 to 5 , wherein a groove for promoting the flow of the lubricant is formed in the working disk . The differential case, the first and second axles that are disposed coaxially with the shaft end faces facing each other, the opposed shaft end portions being disposed in the differential case, and the shaft end of the first axle The first side gear fixed to the shaft, the second side gear fixed to the shaft end of the second axle, and the first and second axles are orthogonal to each other, and both ends rotate to the differential case. A shaft that is freely supported, two spider gears that are rotatably supported by the shaft and mesh with the first and second side gears, and one of the first and second side gears with respect to the differential case. A clutch mechanism that engages and disengages, the clutch mechanism comprising the overrunning clutch mechanism according to any one of claims 1 to 6, and an outer side of the overrunning clutch mechanism. Connecting the over scan the differential device case, and a drive mechanism connecting the inner race on one of the side gears.

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