VEHICLE PARKING LOCKING MECHANISM

Abstract

Vehicle parking locking mechanism (10), comprising: a parking lock wheel (44); a parking pawl (40) provided to be movable closer to and away from the parking lock gear (44) and configured to engage the parking lock gear (44) to prevent rotation of the parking lock gear (44); a locking member (42) arranged to be movable between a locking position and an unlocking position, the locking member (42) being configured to move the parking pawl (40) closer to the parking lock gear (44) via a cam mechanism (96) when the locking member (42) is moved toward the locking position to establish a parking lock state in which rotation of the parking lock gear (44) is prevented by the parking pawl (40) when the locking member (42) is moved to the locking position; and a support member (30) arranged on a side of the locking member (42) opposite the parking pawl (40) and provided with a guide portion (94) configured to guide the movement of the locking member (42) between the locking position and the unlocking position and at the same time restrict the displacement of the locking member (42) towards the opposite side of the parking pawl (40), wherein the cam mechanism (96) comprises a cam roller (62) arranged on the locking member (42) to be rotatable about an axis (S1) at right angles to a direction of movement of the locking member (42), and a cam surface (92) provided on the parking pawl (40) to be engageable with the cam roller (62), wherein the cam mechanism (96) is configured to move the parking pawl (40) closer to the parking lock gear (44) is moved towardsto engage the parking lock gear (44) by engaging the cam surface (92) with the cam roller (62) when the locking member (42) is moved from the unlocking position to the locking position; and wherein in the vehicle parking lock mechanism (10), the locking member (42) has a stopper (66, 120) arranged on the locking member (42) to be rotatable about a rotation axis (S3) which is parallel to the axis (S1) of the cam roller (62) and has a cylindrical outer peripheral surface (102) to be brought into rolling contact with an outer peripheral surface of the cam roller (62), wherein the stopper (66, 120) is rotated about the rotation axis (S3) together with the rotation of the cam roller (62) via the cylindrical outer peripheral surface (102) when the locking member (42) is moved from the unlocking position toward the locking position to assume a projecting position in which the stopper (66,120) in the parking lock state protrudes towards the support element (30) to be engaged with the support element (30).

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to a vehicle parking lock mechanism, and more particularly, to a technique for suppressing "P-out" (hereinafter) "P-release" in which a parking pawl slips off a parking ratchet wheel when a vehicle is parked with a selected parking (P) range.2. Description of the Prior ArtA vehicle parking lock mechanism is known that includes a parking ratchet wheel, a parking pawl, a lock member, and a support member as described below. The parking pawl is provided to be movable closer to and away from the parking gear and engaged with the parking gear to prevent rotation of the parking gear. The locking element is arranged to be reciprocable between a locking position and an unlocking position. The lock member moves the parking pawl closer to the parking ratchet via a cam mechanism when the lock member is moved toward the lock position to establish a parking lock state in which the rotation of the parking ratchet is prevented by the parking pawl when the lock member is moved to the lock position. The support member is disposed on the opposite side of the locking member from the parking pawl and is provided with a guide portion that guides the movement of the locking member between the locking position and the unlocking position while restraining the displacement of the locking member toward the opposite side of the parking pawl. In the vehicle parking lock mechanism, the cam mechanism includes a cam roller disposed on the lock member to be rotatable about an axis perpendicular to the moving direction of the lock member, and a cam surface provided on the parking pawl to be engageable with the cam roller, wherein the cam mechanism is configured such that the parking pawl is moved closer to the parking ratchet wheel to be engaged with the parking ratchet wheel by engaging the cam surface with the cam roller when the lock member is moved from the unlocking position to the locking position. JP 2002-178 891 A describes an example of such a device in which a clamping body 2 of the parking pawl, a rod 4 provided with a pair of rollers 7 corresponds to the locking element and a pressure element 3 corresponds to the supporting element. DE 101 44 058 A1 discloses a parking lock for an automatic transmission of a motor vehicle. The post-published U.S. Pat. No. 2022 / 0 018 434 A1 of the applicant also explains such a parking lock.In the vehicle parking lock mechanism, when a P range is selected for parking with a shift lever, etc., the wheels are locked from rotating via a rotating shaft on which a parking ratchet wheel is provided by engaging the parking pawl with the parking ratchet wheel by moving the lock member to the lock position. In this case, when the road surface inclination at the location where the vehicle is parked is large, in accordance with the torque applied to the parking ratchet wheel by the weight of the vehicle, a pushing-out load that pushes the parking pawl away from the parking ratchet wheel is generated. The push-out force moves the locking member back toward the unlocking position, which may result in a P-release operation in which the parking pawl slips off the parking ratchet wheel. For example, when a lock-side engagement surface of a parking pawl to be engaged with a cam roller in a parking lock state is inclined in the direction in which it moves away from a guide member toward a parking unlock position due to variations in dimensions of components, etc., torque is occasionally generated due to the inclination, which rolls the cam roller toward the unlock position, and a force is occasionally applied to the lock member in the direction of movement back to the unlock position. In view of this, it is proposed in JP 2018-141 520 A to provide a stopper (a wedge limiting unit) that can be advanced into and retracted from a moving path for a locking member (wedge), the stopper being advanced and retracted in conjunction with a shift lever to suppress a P-releasing operation by preventing a rearward movement of the locking member.SUMMARY OF THE INVENTIONHowever, in such a vehicle parking lock mechanism according to the related art, there is a problem that the lock member is abutted with the stopper protruding into the movement path for the lock member from a lateral direction and therefore a bending load is applied to the stopper, which can increase the strength required for various portions including the stopper and increase the size of the device, resulting in an increase in the space in the vehicle for mounting the device, etc.The present invention aims to suppress a P release operation when a vehicle is parked on a descending road, and at the same time, to prevent enlargement of the device.An aspect of the present invention provides a vehicle parking lock mechanism including a parking ratchet, a parking pawl, and a support member. The parking pawl is provided to be movable closer to and away from the parking gear and is configured to be engaged with the parking gear to prevent rotation of the parking gear. The locking member is arranged to be reciprocable between a locking position and an unlocking position, the locking member being configured to move the parking pawl closer to the parking ratchet via a cam mechanism when the locking member is moved toward the locking position to establish a parking locked state in which rotation of the parking ratchet is prevented by the parking pawl when the locking member is moved to the locking position. The support member is disposed on an opposite side of the locking member from the parking pawl and provided with a guide portion configured to guide the movement of the locking member between the locking position and the unlocking position while restricting the displacement of the locking member toward the opposite side of the parking pawl. The cam mechanism includes a cam roller disposed on the locking member to be rotatable about an axis at right angles to a moving direction of the locking member, and a cam surface provided on the parking pawl to be engageable with the cam roller, wherein the cam mechanism is configured such that the parking pawl is moved closer to the parking ratchet wheel to be engaged with the parking ratchet wheel by the cam surface being engaged with the cam roller when the locking member is moved from the unlocked position to the locked position. In the vehicle parking lock mechanism, the lock member includes a stopper disposed on the lock member to be rotatable about a rotation axis that is parallel to the axis of the cam roller and has a cylindrical outer circumferential surface to be brought into rolling contact with an outer circumferential surface of the cam roller, the stopper being rotated about the rotation axis together with the rotation of the cam roller via the cylindrical outer circumferential surface when the lock member is moved from the unlocking position toward the locking position to be engaged with the support member by taking a protruding position in which the stopper protrudes toward the support member in the parking lock state.In the vehicle parking lock mechanism according to the above-described aspect, the stopper disposed on the lock member takes the protruding position to protrude toward the support member in the parking lock state. Therefore, the stopper is pressed between the cam roller and the support member when, when the vehicle is parked on a downhill road, a pushing-out force is generated, which pushes the parking pawl away from the parking ratchet wheel, and the pushing-out force is applied from the parking pawl to the cam roller. Since changes in the position of the stopper are limited by the pressing force, the rotation of the cam roller engaged with the cylindrical outer circumferential surface of the stopper is suppressed, the torque of the cam roller in the direction of the return movement of the lock member toward the unlock position is reduced, and a P-release operation in which the parking pawl slips off the parking ratchet when the lock member is returned is suppressed. In this case, the stopper is pressed between the cam roller and the support member to receive a pressing load, and therefore, the strength required for the stopper, etc., is reduced as compared with the case where a bending load is applied as in the related art, enabling size reduction.In the vehicle parking lock mechanism according to the aspect, a gap between the stopper and the support member may be equal to or smaller than a gap between the lock member and the guide portion, the stopper being in the protruding position in the parking lock state.According to the vehicle parking lock mechanism having the above configuration, the gap between the stopper that is in the protruding position in the parking lock state and the support member is equal to or smaller than the gap between the lock member and the guide portion. Therefore, the stopper is reliably pressed between the cam roller and the support member when a pushing-out force is applied to the cam roller, and the effect of suppressing a P release operation at the time when the vehicle is parked on a descending road is suitably achieved.In the vehicle parking lock mechanism according to the aspect, the stopper may be disposed on the lock member such that the rotation axis and the axis of the cam roller are on a line perpendicular to the moving direction of the lock member.According to the vehicle parking lock mechanism having the above configuration, the rotation axis of the stopper and the axis of the cam roller lie on a line perpendicular to the moving direction of the lock member. Therefore, the stopper is reliably pressed between the cam roller and the support member by a pushing-out force applied from the parking pawl, and the effect of suppressing a P release operation at the time when the vehicle is parked on a descending road is suitably achieved.In the vehicle parking lock mechanism according to the aspect, an engagement portion of the stopper in the protruding position for engaging with the support member may include a portion on a side of the unlocking position with respect to the rotation axis in the moving direction of the lock member.According to the vehicle parking lock mechanism having the above configuration, the engagement portion between the stopper that is in the parking lock state in the protruding position and the support member includes a portion on the side of the unlocking position with respect to the rotation axis of the stopper in the moving direction of the lock member. Therefore, when a pushing-out force acts on the cam roller to bias the locking member toward the unlocking position, the rotation axis of the stopper is shifted toward the parking pawl when the position of the stopper is changed using the engagement portion on the support member side as the fulcrum. In this case, the locking element and the cam roller are pushed back by displacement of the rotational axis in the direction of the parking pawl. However, when a pushing-out force is applied to the parking pawl, a lock state is substantially established, and the movement of the lock member toward the unlock position is prevented to further suitably suppress a P release operation.According to the vehicle parking lock mechanism having the above configuration, an engagement surface on a side of the support member to be engaged with the stopper on the engagement portion may be inclined with respect to a line parallel to the moving direction of the lock member in a direction away from the rotation axis toward the lock position.According to the vehicle parking lock mechanism having the above configuration, the engagement surface on the support member side to be engaged with the stopper is inclined in the direction away from the rotation axis toward the lock position. Therefore, when a pushing-out force acts on the cam roller and the stopper is pressed against the support member, a torque toward the locking position is generated in the rotational axis of the stopper based on the inclination of the engagement surface of the support member, and a force toward the locking position is applied from the stopper to the locking member. Therefore, movement of the lock member toward the unlock position is prevented to further appropriately suppress a P release operation.According to the vehicle parking lock mechanism having the above configuration, an engagement surface on a side of the stopper to be engaged with the support member at the engagement portion may be inclined toward the locking position in a direction closer to the rotation axis with respect to a line parallel to the moving direction of the lock member.According to the vehicle parking lock mechanism having the above configuration, the engagement surface on the stopper side to be engaged with the support member is inclined in the direction closer to the rotation axis toward the lock position. Therefore, when a pushing-out force acts on the cam roller and the stopper is pressed against the support member, a torque toward the locking position is generated in the rotational axis of the stopper based on the inclination of the engagement surface of the support member, and a force toward the locking position is applied from the stopper to the locking member. Therefore, movement of the lock member toward the unlock position is prevented to further appropriately suppress a P release operation.In the vehicle parking lock mechanism according to this aspect, the outer circumferential surface of the cam roller may be provided with a fixing portion that protrudes toward the lock position in the parking lock state to be brought into contact with the parking pawl over a predetermined engagement length.According to the vehicle parking lock mechanism having the above configuration, the outer circumferential surface of the cam roller is provided with a fixing portion that is brought into contact with the parking pawl over a predetermined engagement length in the parking lock state. Therefore, when a pushing-out force is applied from the parking pawl to the cam roller when the vehicle is parked on a descending road, the fixing portion is relatively pressed against the parking pawl to cause sliding friction, and the rotation resistance is increased based on the sliding friction before the cam roller starts rolling. Consequently, a force in the direction of returning to the unlocking position applied to the locking member is reduced together with the rolling of the cam roller, which further reliably suppresses the P releasing operation at the time when the vehicle is parked on a descending road, in addition to the P releasing operation suppressing effect due to the stopper.In the vehicle parking lock mechanism according to this aspect, the lock member may be provided with a guide roller to be engaged with the guide portion and rolled to rotate when the lock member is moved between the lock position and the unlock position to restrict displacement of the lock member toward the opposite side of the parking pawl.According to the vehicle parking lock mechanism having the above configuration, the guide roller that is engaged with the guide portion and rolled to rotate to restrict displacement of the lock member toward the opposite side of the parking pawl is disposed on the lock member, and the lock member is smoothly moved between the lock position and the unlock position by the rotation of the cam roller and the guide roller, the cam roller being engaged with the cam surface and the guide roller being engaged with the guide portion. In this case, when a pushing-out force pushing the parking pawl away from the parking ratchet wheel is generated when the vehicle is parked on a descending road, the pushing-out force slightly moves the lock member toward the unlock position, which may cause a P-releasing operation. Therefore, according to the present invention, a remarkable effect of suppressing the P releasing operation at the time when the vehicle is parked on a descending road is achieved by the provision of the stopper.BRIEF DESCRIPTION OF THE DRAWINGSFeatures, 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 reference numerals denote like elements, and wherein: FIG. 1 is a diagram showing a schematic configuration of a vehicle parking lock mechanism according to a first embodiment of the present invention in a parking lock state; FIG. 2 is a front view, partially in section, showing a portion of the vehicle parking lock mechanism in FIG. 1 near a lock member; FIG. 3 is a front view corresponding to FIG. 2 and showing the vehicle parking lock mechanism in FIG. 1 in an unlocked state; FIG. 4 is a front view showing only a coupling head of the locking member of the vehicle parking lock mechanism in FIG. 1 ; FIG. 5 is a plan view of the coupling head in FIG. 4 ; FIG. 6 is a sectional view taken along line VI-VI in FIG. 5 ; FIG. 7 shows a stopper in a protruding position provided on the locking member of the vehicle parking lock mechanism in FIG. 1, and shows a state in which the stopper is engaged with a support member; FIG. 8 shows the manner of engagement between the stopper and the support member according to a first modification of the first embodiment including an enlarged view of the engagement portion; FIG. 9 shows the manner of engagement between the stopper and the support member according to a second modification of the first embodiment including an enlarged view of the engagement portion; FIG. 10 shows the manner of engagement between the stopper and the support member according to a third modification of the first embodiment corresponding to FIG. 7 for the first embodiment; FIG. 11 shows a second embodiment of the present invention, which corresponds to FIG. 2 for the first embodiment; FIG. 12 shows a third embodiment of the present invention, showing the vicinity of the stopper in the locked state; FIG. 13 shows a fourth embodiment of the present invention, which corresponds to FIG. 7 for the first embodiment; FIG. 14 is a front view of a fifth embodiment of the present invention showing a cam mechanism portion in the parking lock state enlarged; and FIG. 15 shows the fifth embodiment in FIG. 14 in the unlocked state.DETAILED DESCRIPTION OF THE EMBODIMENTSA vehicle parking lock mechanism according to the present invention is applied to a manual operation parking lock mechanism in which a shift range is mechanically shifted with a shift lever via a lock device such as a link and a cable. However, the vehicle parking lock mechanism may also be used for a shift-by-wire (SBW) type parking lock mechanism in which a shift range selected by a shift range selection device such as a shift lever is electrically set by an electric type shift actuator, a hydraulic type shift actuator, etc. The shift range includes at least a park (P) range in which power transmission is blocked and rotation of an output shaft is mechanically prevented. When the P range is selected, the parking lock mechanism is brought into a parking lock state. Besides the P range, the shift range includes, for example, a drive (D) range that enables forward travel, a reverse (R) range that enables reverse travel, etc. The vehicle may be a plurality of vehicles, for example, a motor-driven vehicle that generates power by combustion of fuel, an electric vehicle that is driven by an electric motor, and a hybrid vehicle that includes a plurality of power sources.On a rotation shaft (e.g., an output shaft) that mechanically rotates with the rotation of the wheels, a parking lock gear is provided. A parking pawl is engaged with the parking ratchet wheel to mechanically prevent rotation of the rotating shaft and thus rotation of the wheels. A locking element is arranged, for example, at the distal end portion of a parking pole and is moved back and forth together with the parking pole between a locking position and an unlocking position. The locking element can be moved back in the direction of the unlocking position by a biasing device, e.g. a spring element.When a stopper is in a protruding position in the parking lock state, a torque is applied to the parking ratchet wheel by the weight of the vehicle on a descending road, etc., and a pushing-out force is generated that pushes the parking pawl away from the parking ratchet wheel. When the pushing-out force is applied from the parking pawl to a cam roller, at least a part of the pushing-out force may be transmitted to a support member via the stopper. That is, even if a gap exists between the stopper and the support member before a pushing-out force is applied, the stopper can be brought into abutment with the support member by elastic deformation etc. of various portions before the locking member is moved back when the pushing-out force is applied. When the gap between the stopper and the support member in the locked state is equal to or smaller than the gap between the locking member and a guide portion, the stopper can be reliably caused to abut on the support member when a pushing-out force is applied. However, when the gap between the stopper and the support member is larger than the gap between the locking member and the guide portion, the stopper may be abutted to the support member by elastic deformation etc. of various portions before the locking member is moved back.The stopper is brought into a protruding position when the locking member is moved from the unlocking position to the locking position by relatively rotating the stopper together with the rotation of the cam roller, for example, and a retracting position in which the stopper is detached from the support member and engagement between the locking member and the guide portion is possible when the locking member is moved from the locking position to the unlocking position. When there is a possibility that the stopper or the cam roller slips, the stopper may be rotated about the rotation axis using a biasing device, e.g., a spring, or the support member may be provided with a guide surface, an abutment surface, a link, etc., to be engaged with the stopper to change its position, to reliably change the position of the stopper between the protruding position and the retracting position together with the movement of the locking member.For example, the stopper and the cam roller are arranged to be rotatable to a certain arrangement position set on the locking member. However, the cam roller may be disposed on the locking member so as to be slidable in a direction perpendicular to the moving direction of the locking member, so that the outer circumferential surface of the cam roller can be reliably brought into contact with the cylindrical outer circumferential surface of the stopper. A pushing-out force applied to the parking pawl in the locked state is transmitted to the cam roller and transmitted from the cam roller to the support member via the stopper. However, a part of the pushing-out force applied to the cam roller may be transmitted to the stopper via the locking member, for example, when both the stopper and the cam roller are disposed at certain arrangement positions on the locking member.For example, the stopper is disposed on the locking member such that the rotation axis of the stopper and the axis of the cam roller are on a line perpendicular to the moving direction of the locking member. However, the rotation axis of the stopper may be set to be shifted toward the locking position or toward the unlocking position with respect to the axis of the cam roller. When the rotation axis of the stopper is shifted with respect to the axis of the cam roller toward the locking position, for example, a torque is generated in the cam roller toward the rolling to the locking position due to the deviation between the respective axes of the stopper and the cam roller when the cam roller is pressed against the stopper based on the pushing-out force, whereby a P-release operation is further reliably suppressed when the vehicle is stopped on a downhill road.An engagement portion between the stopper in the protruding position in the parking lock state and the support member is determined to include, for example, the same position as the rotation axis in the moving direction of the lock member. However, it is desirable that the engaging portion includes a portion on the side of the unlocking position with respect to the rotation axis. Further, the respective engagement surfaces of the stopper and the support member at the intermediate engagement portion are determined to be parallel to the moving direction of the lock member, for example. However, a variety of aspects are possible. For example, the engagement surface on the support member side of the engagement portion may be inclined in a direction away from the rotation axis toward the locking position, or conversely, the engagement surface on the stopper side may be inclined in a direction closer to the rotation axis toward the locking position, or the engagement surfaces of both the stopper and the support member may be inclined.The outer circumferential surface of the cam roller may be provided with, for example, a fixing portion that protrudes toward the locking position in the locked state to be brought into contact with the parking pawl over a predetermined engagement length. However, the outer circumferential surface of the cam roller may be a cylindrical surface centered around the axis over the entire circumference. Further, the locking member is provided with a guide roller to be engaged with the guide portion and rolled to rotate when the locking member is moved between the locking position and the unlocking position to limit displacement of the locking member toward the opposite side of the parking pawl. However, a guide roller may not be provided, and a part of the locking member may be brought into sliding contact with the guide portion. The guide roller may be provided at a desired position of the locking member. However, the guide roller may be provided integrally with the stopper, for example.Embodiments of the present invention will be described in detail below with reference to the drawings. In the following embodiments, the drawings are simplified or deformed for illustrative purposes, and the dimensional ratios, shapes, etc. of the various portions are not necessarily accurate.FIG. 1 is a diagram showing a schematic configuration of a vehicle parking lock mechanism 10 according to a first embodiment as an example of the present invention. The vehicle parking lock mechanism 10 is a manual parking pawl in which the shift range is mechanically switched by a shift lever 12 via a lock device 14, e.g., a link or a push-pull cable. The shift lever 12 is disposed in the vicinity of the driver's seat and is rotated to four positions, namely, a park (P) position, a reverse (R) position, a neutral (N) position, and a drive (D) position, according to a shift operation by the driver. The P position is a shift position for selecting a P range for parking in which transmission is blocked and rotation of an output shaft 16 of an automatic transmission is mechanically prevented. The R position is a shift operation position for selecting an R range that enables reverse travel. The N position is a shift operation position for selecting an N range in which the transmission is blocked. The D position is a shift position for selecting a D range that enables forward travel.The shift lever 12 is coupled to an outer lever 18 via the locking device 14. The outer lever 18 is fixed to a manual shaft 20. A detent plate 22 is secured to the manual shaft 20. The detent plate 22 is rotated about the axis of the manual shaft 20 according to the shift position of the shift lever 12 and positioned at four rotational positions, namely, the P position, the R position, the N position and the D position. Recesses and projections having four positioning recesses 24 are provided at the distal end portion of the detent plate 22 to allow a holding portion 26 to be engaged with the positioning recesses 24. The holding portion 26 is formed by bending the distal end portion of a leaf spring 28 and displaced according to the recessed and protruding shape by elastic deformation of the leaf spring 28, and applies predetermined damping (positioning force) to the detent plate 22 in each of the P, R, N, and D rotational positions. The leaf spring 28 is fixed to a support member 30 fixed to a gear case, etc. In FIG. 1, the shift lever 12 is placed in the P position, and the ratchet plate 22 is mechanically rotated clockwise about the manual shaft 20 to be held in the P position.The detent plate 22 is provided with a coupling hole 32. A parking pole 34 is relatively rotatably coupled to the clutch hole 32. The parking pole 34 is reciprocated substantially linearly in the longitudinal direction of the parking pole 34, i.e., in the right-left direction in FIG. 1, together with the rotation of the lock plate 22 to be moved to a locking position located in the right direction in FIG. 1 and an unlocking position located in the left direction. In the locking position, as shown in FIG. 1, the shift lever 12 is operated to the P position, and the detent plate 22 is rotated clockwise about the manual shaft 20 to the P position. In the unlock position, the shift lever 12 is operated to a non-P position such as the R position, and the ratchet plate 22 is rotated counterclockwise about the manual shaft 20 to a non-P position such as the R position. In the first embodiment, a play mechanism is provided between the shift lever 12 and the parking pole 34 so that the parking pole 34 is constantly maintained in the unlock position when the shift lever 12 is in a non-P position including the positions R to D. In other words, the parking pole 34 is placed in the lock position that is in the right direction in FIG. 1 when the shift lever 12 is placed in the P position, and the parking pole 34 is placed in the unlock position that is in the left direction in FIG. 1 when the shift lever 12 is placed in the R position. When the shift lever 12 is operated between the non-P positions including the positions R to D, the parking pole 34 is constantly maintained at the unlocking position regardless of the shift operation.A lock member 42 to be engaged with a parking pawl 40 is disposed at the distal end portion of the parking pole 34. When the lock member 42 is moved to the lock position together with the parking pole 34, the parking pawl 40 is rotated downward in FIG. 1, and an engagement gear 40 pis engaged with a parking ratchet 44. The parking lock gear 44 is fixed relatively rotationally fixedly to the output shaft 16 of the automatic transmission. The parking pawl 40 is disposed on a transmission case, etc. so as to be rotatable about the axis of a pawl shaft 46 that is parallel to the output shaft 16, and biased in a non-engagement direction (clockwise in FIG. 1 ) by a return spring 48 as a biasing device. The lock member 42 rotates the parking pawl 40 in an engagement direction (counterclockwise in FIG. 1 ) against the biasing force of the return spring 48. That is, the parking pawl 40 is disposed such that the engagement gear 40 pcan be moved closer to and away from the parking ratchet 44. When the parking pawl 40 is rotated in the engaging direction or downward in FIG. 1 by the locking member 42, the engaging gear 40 pis moved closer to the parking ratchet 44 to be engaged therewith, thereby establishing a parking locked state in which the rotation of the parking ratchet 44 and further the rotation of the output shaft 16 and the wheels is mechanically prevented. In FIG. 1, the parking lock state is illustrated.The locking member 42 is biased toward the distal end side of the parking pole 34 by a spring member (a compression coil spring in the first embodiment) 50 as a biasing device and held at the distal end position on the locking position side to rotate the parking pawl 40 in the engagement direction. However, when the parking pawl 40 and the parking ratchet 44 cooperate, the locking member 42 may be relatively moved back toward the unlocking position with respect to the parking pole 34 against the biasing force of the spring member 50. The lock member 42 is supported by the support member 30 to be linearly and reciprocally movable between the lock position and the unlock position with predetermined play, i.e., in the state of being slidable in a direction perpendicular to the moving direction (up-down direction in FIG. 1 ). Further, the manual shaft 20 is disposed on the opposite side of the output shaft 16 from the ratchet shaft 46 in a position parallel to the output shaft 16, and the lock member 42 is movable closer to the parking pawl 40 from the distal end side (left side in FIG. 1 ) of the parking pawl 40.FIGS. 2 and 3 are each a partially cut front view of the locking member 42 and a portion near the same in detail. FIG. 2 shows the same parking lock state as in FIG. 1, FIG. 3 shows the unlocking state in which the locking member 42 is moved to the unlocking position and the engagement between the parking pawl 40 and the parking ratchet 44 is released. In the drawings, the locking member 42 is configured to include a coupling head 60, a cam roller 62, a guide roller 64, and a stopper 66.FIG. 4 is a front view showing only the coupling head 60. FIG. 5 is a plan view of the clutch head 60; FIG. 6 is a sectional view taken along a line VI-VI in FIG. 5 ; the clutch head 60 includes a substantially U-shaped branched clutch portion 72 provided with an insertion hole 70 through which the parking pole 34 is inserted, and a pair of side wall portions 74 extending from both ends of the clutch portion 72 in parallel to each other in the axial direction of the insertion hole 70. As illustrated in FIGS. 2 and 3, the parking pole 34 is inserted through the insertion hole 70 and relatively movable in the axial direction. To the distal end portion of the parking rod 34 protruding from the insertion hole 70 into the coupling head 60, a nut 76 is fastened. The spring member 50 is held at the peripheral edge portion of the insertion hole 70. Thus, the coupling head 60 is normally held at the distal end position of the parking pole 34 where the coupling portion 72 is brought into abutment with the nut 76 according to the biasing force of the spring member 50 and can be moved away from the nut 76 against the biasing force of the spring member 50 to be relatively moved back with respect to the parking pole 34 toward the unlocking position.The coupling head 60 is held by the support member 30 in such a position that the side wall portions 74 are perpendicular to the axis of the output shaft 16, i.e., in such a position that the side wall portions 74 are parallel to the sheet surface of FIGS. 1 to 3 and spaced apart from each other in the front-rear direction of the sheet surface. The side wall portions 74 are respectively provided with a cam roller mounting hole 80, a guide roller mounting hole 82, and a stopper mounting hole 84 at the same position. A reinforcing coupling portion 86 is provided at the distal end portion of the side wall portions 74 on the opposite side of the coupling portion 72.The cam roller mounting hole 80 is an elongated hole long in a direction perpendicular to the longitudinal direction of the side wall portions 74, i.e., in the up-down direction perpendicular to the moving direction of the lock member 42, and holds the cam roller 62 in the position where it is substantially parallel to the output shaft 16 with predetermined play in the up-down direction, as shown in FIGS. 2 and 3. That is, both end portions of the cam roller 62 are supported by the cam roller mounting holes 80 of the side wall portions 74, the cam roller 62 being rotatable about an axis S 1 perpendicular to the moving direction of the lock member 42. The guide roller mounting hole 82 is provided at a position offset toward the upper side and toward the coupling portion 72, i.e., toward the unlocked position, with respect to the cam roller mounting hole 80, and holds the guide roller 64 in the position substantially parallel to the output shaft 16, as shown in FIGS. 2 and 3. That is, both end portions of the guide roller 64 are supported by the guide roller mounting holes 82 of the side wall portions 74, the guide roller 64 being rotatable about an axis S 2 perpendicular to the moving direction of the lock member 42. The stopper fixing hole 84 is provided at a position above the cam roller fixing hole 80 and holds the stopper 66 so as to be rotatable about a rotation axis S 3 perpendicular to the moving direction of the lock member 42 via a fixing pin 100, as shown in FIGS. 2 and 3. That is, the fixing pin 100 protrudes to both side portions of the stopper 66, and the both side portions are inserted into the stopper fixing holes 84 of the side wall portions 74 to be supported, so that the stopper 66 is rotatably held between the side wall portions 74 about the rotation axis S 3 that is parallel to the output shaft 16. The stopper 66 may be rotatably fixed with respect to the fixing pin 100, or the fixing pin 100 may be rotatably fixed with respect to the side wall portions 74. The cam roller 62, the guide roller 64, and the fixing pin 100 of the stopper 66 are prevented from falling out of the coupling head 60 by a pair of pressing plates 90 (see FIG. 1 ) fixed with bolts 88 so as to firmly contact the outer side surfaces of the side wall portions 74. The cam roller 62 and the guide roller 64, like the stopper 66, may also be disposed on the coupling head 60 via a fixing pin.The cam roller 62 is engaged with and rolled to rotate the parking pawl 40 when the locking member 42 is moved from the unlocked position to the locked position to move the parking pawl 40 closer to the parking ratchet wheel 44 to engage therewith. The parking pawl 40 is provided with a cam surface (a slant surface in the first embodiment) 92 to be engaged with the cam roller 62 to rotate the parking pawl 40 in the engaging direction. Further, the guide roller 64 is engaged with a guide portion 94 provided on the support member 30 and rolled to rotate when the locking member 42 is moved between the locking position and the unlocking position to limit the displacement of the locking member 42 toward the opposite side of the parking pawl 40. The guide portion 94 is provided in parallel (right-left direction in FIGS. 1 to 3 ) to the moving direction of the locking member 42 on the opposite side of the locking member 42 to the parking pawl 40, and guides the locking member 42 via the guide roller 64 to reciprocate substantially linearly between the locking position and the unlocking position while limiting the displacement of the locking member 42 toward the opposite side of the parking pawl 40. In the first embodiment, the guide roller 64 is smaller in diameter than the cam roller 62, but the diameter of the guide roller 64 can be determined as desired.When the locking member 42 is moved from the unlock position to the lock position, the cam roller 62 and the guide roller 64 are engaged with the parking pawl 40 and the guide portion 94, respectively, and are rolled to rotate about the axes S 1 and S 2, respectively, whereby the parking pawl 40 can be rotated in the engaging direction by the engagement between the cam roller 62 and the cam surface 92 and engaged with the parking ratchet wheel 44 while the displacement of the locking member 42 toward the opposite side of the parking pawl 40 is restricted. In the parking lock state in which the lock member 42 is moved to the lock position, the cam roller 62 is engaged with a lock-side engagement surface 40 a(see FIG. 2 ) provided on the parking pawl 40 so as to extend parallel to the moving direction of the lock member 42, and the cam roller 62 and the guide roller 64 are disposed between the lock-side engagement surface 40 aand the guide portion 94, both of which are provided parallel to the moving direction of the lock member 42. Consequently, the parking lock state is stably held by the rolling resistance of the cam roller 62 and the guide roller 64. In the first embodiment, a cam mechanism 96 is formed that includes the cam roller 62 and the cam surface 92 and in which the parking pawl 40 is moved closer to the parking ratchet 44 to engage therewith.When a torque is applied to the parking ratchet 44 due to the weight of the vehicle when parking on a downhill road, a pushing-out force is generated corresponding to the torque, pushing the parking pawl 40 away from the parking ratchet 44. When such a pushing-out force is applied from the parking pawl 40 to the cam roller 62, the lock member 42 is moved back to the unlocking position even in the parking lock state that is maintained relatively stably, which may result in a P-releasing operation in which the engagement gear 40 pof the parking pawl 40 slips off the parking ratchet 44. For example, when the lock-side engagement surface 40 aof the parking pawl 40 to be engaged with the cam roller 62 is inclined toward the unlock position due to variations in dimensions of components, etc., in the direction of movement away from the guide portion 94, a torque that the cam roller 62 rolls toward the unlock position is occasionally generated due to the inclination, and a force in the direction of return movement toward the unlock position is occasionally applied to the lock member 42.In the present embodiment, therefore, the P releasing operation is suppressed by the stopper 66 provided on the lock member 42. As illustrated in FIG. 7 in an enlarged manner, the stopper 66 is disposed on the locking member 42 such that the rotation axis S 3 of the stopper 66 and the axis S 1 of the cam roller 62 are positioned on a vertical line V 1 that is perpendicular to an extension line of the guide portion 94 extending in the moving direction of the locking member 42. That is, the respective centers of the cam roller attachment hole 80 and the stopper attachment hole 84 provided in the coupling head 60 are set to be positioned on the vertical line V 1. Further, the stopper 66 includes an outer circumferential cylindrical surface 102 to be brought into rolling contact with the outer circumferential surface of the cam roller 62, and a protruding portion 104 protruding in the opposite direction of the outer circumferential cylindrical surface 102 about the rotation axis S 3. When the lock member 42 is moved between the unlock position and the lock position, the stopper 66 is rotated about the rotation axis S 3 along with the rotation of the cam roller 62 via the cylindrical outer circumferential surface 102 to be varied in position between a protruding position illustrated in FIG. 2 and a retracting position illustrated in FIG. 3. FIG. 7 shows the same parking lock state as in FIG. 2 in which the stopper 66 is in the protruding position in which the protruding portion 104 protrudes toward the support member 30. The cylindrical outer peripheral surface 102 is a cylindrical surface centered on the rotation axis S 3, and is provided for a predetermined angular range (about 280° in the first embodiment) except for the protruding portion 104. In the first embodiment, the radius of the cylindrical outer peripheral surface 102 is substantially equal to the radius of the cam roller 62, but the radius of the cylindrical outer peripheral surface 102 may be determined as needed, for example, depending on the protruding position and the retracting position.When the stopper 66 is in the protruding position, a flat engagement surface 104a provided at the distal end portion of the protruding portion 104 is abutted to firmly contact a flat engagement surface 30a provided on the support member 30, the engagement surfaces 30a, 104a being perpendicular to the vertical line V1. The engagement surface 30 ais a planar surface that is parallel to the guide portion 94, i.e., parallel to the moving direction of the lock member 42, and is caused to firmly contact the engagement surface 104 ain an engagement region L 1 that is both sides of the vertical line V 1 passing through the rotation axis S 3 in the moving direction of the lock member 42. The engagement range L 1 is appropriately determined in advance by experiment etc., so that a targeted P release operation suppressing effect is obtained and the P release operation is appropriately performed together with a shift operation of the shift lever 12. The stopper 66 has a width (about 12 mm in the first embodiment) slightly smaller than the inner dimension of the side wall portions 74 of the coupling head 60. The shape of the distal end portion of the stopper 66 is changeable as needed as long as the required strength is achieved, such as a hemispherical shape that allows the stopper 66 to substantially make point contact with the support member 30, or a semi-cylindrical shape having a semicircular cross section that allows the stopper 66 to make parallel line contact with the support member 30 parallel to the rotation axis S 3. The engagement surface 30 aon the support member 30 side may have a semi-spherical or semi-cylindrical shape.In order to allow the stopper 66 to be placed in the protruding position in the parking lock state in FIG. 7, the support member 30 is provided with a stopper guide surface 106 on the locking position side with respect to the engagement surface 104 aand a stopper abutment surface 108 on the unlocking position side with respect to the engagement surface 104 a. That is, the stopper 66 is rotated about the rotation axis S 3 together with the rotation of the cam roller 62, and there is a possibility of a deviation in the rotation phase due to slip, etc. Therefore, when the rotation of the stopper 66 is decelerated when the locking member 42 is moved from the unlocking position to the locking position, the stopper 66 is rotated counterclockwise in FIG. 7 by the stopper guide surface 106, so that the stopper 66 is reliably brought into abutment with the stopper abutment surface 108 to take the protruding position when the locking member 42 is moved to the locking position. As the rotation of the stopper 66 proceeds, the stopper 66 is brought into abutment with the stopper abutment surface 108 to be held at the protruding position when the locking member 42 is moved to the locking position. A biasing device, such as a torsion coil spring or a Belleville spring, may be provided to bias and rotate the stopper 66 counterclockwise about the fixing pin 100.The dimension, arrangement position, etc. of the stopper 66 are determined such that the gap between the engagement surface 104 aand the engagement surface 30 ais equal to or smaller than the gap between the guide roller 64 and the guide portion 94, and both gaps are substantially zero in the first embodiment when no pushing-out force is applied, so that the engagement surface 104 aand the engagement surface 30 aare engaged with each other before the locking member 42 is moved back toward the unlocking position when a pushing-out force, upward in FIG. 7, is applied from the parking pawl 40 to the cam roller 62 on a descending road, etc. In this case, the stopper 66 is pressed between the cam roller 62 and the support member 30, with the engagement surface 104 aand the engagement surface 30 aengaged with each other before the lock member 42 is moved back toward the unlock position when a pushing-out force is applied to the parking pawl 40 on a descending road, etc., changes in the posture of the stopper 66 (rotating about the rotation axis S 3) are suppressed by the pressing force. In the first embodiment, the engagement surface 104 aand the engagement surface 30 aare brought into surface contact in a position perpendicular to the vertical line V 1, and therefore the position of the stopper 66 is stable, suppressing rotation of the stopper 66 in each direction. Therefore, the rotation of the cam roller 62 engaged with the cylindrical outer circumferential surface 102 of the stopper 66 is suppressed, and the torque in the direction of rolling toward the unlocking position generated in the cam roller 62 by the pushing-out force, i.e., the torque of the cam roller 62 in the moving direction of the lock member 42 back to the unlocking position is reduced, and the P release operation in which the parking pawl 40 slips off the parking ratchet 44 when the lock member 42 is moved back is suppressed.The stopper 66 in the protruding position and the support member 30 are engaged with each other in the engagement area L 1 including both sides of the vertical line V 1 passing through the rotation axis S 3 in the moving direction of the lock member 42 and a portion on the side of the unlock position with respect to the rotation axis S 3. Therefore, when a pushing-out force acts on the cam roller 62 and a force in the direction of returning toward the unlock position is applied to the lock member 42, the position of the stopper 66 is changed using an engagement point P 1 located in the engagement region L 1 and on the unlock position side as a fulcrum, and the fixing pin 100 is rotated about the engagement point P 1 in the lower left direction in FIG. 7. That is, a force in the direction of pushing back toward the parking pawl 40 is applied to the locking member 42 via the fixing pin 100, so that the locking member 42 is substantially locked with the pushing-out force applied from the parking pawl 40, and the movement of the locking member 42 toward the unlocking position is prevented to further appropriately suppress a P-releasing operation. In the first embodiment, the engagement portion L 1 corresponds to the engagement portion.On the other hand, when the lock member 42 is moved from the lock position to the unlock position, the stopper 66 is rotated about the rotation axis S 3 along with the rotation of the cam roller 62 via the cylindrical outer circumferential surface 102 to assume the retreat position. In the retracted position, the engagement surface 104 ais moved away from the engagement surface 30 a, the guide portion 94 can guide the locking member 42, and the guide roller 64 can be reliably brought into contact with the guide portion 94. The retracted position is not limited to the position of the stopper 66 in the unlocked position in FIG. 3. FIG. 3 corresponds to the unlocked state in which the locking member 42 moves to the unlocked position and the engagement between the parking pawl 40 and the parking ratchet 44 is released, and in which the cam roller 62 is engaged with an unlocking-side engagement surface 40 bsubstantially parallel to the moving direction of the locking member 42 after passing through the cam surface 92. Even if slipping occurs between the stopper 66 and the cam roller 62 or between the cam roller 62 and the parking pawl 40, the position of the stopper 66 is changed with the movement of the locking member 42 toward the unlocking position so that the stopper 66 slides on the guide portion 94 together with the movement of the locking member 42 and the stopper 66 assumes the retracted position in which the guide roller 64 can be brought into contact with the guide portion 94. The guide portion 94 also functions as a posture converting portion that varies the posture of the stopper 66.In the vehicle parking lock mechanism 10 according to the first embodiment, the stopper 66 disposed on the lock member 42 thus takes the protruding position and protrudes toward the support member 30 in the parking lock state. Therefore, the stopper 66 is pressed between the cam roller 62 and the support member 30 when a pushing-out force is generated that pushes the parking pawl 40 away from the parking ratchet wheel 44 when the vehicle is parked on a descending road and the pushing-out force is applied from the parking pawl 40 to the cam roller 62. Since variations in the position of the stopper 66 by the pressing force are suppressed, the rotation of the cam roller 62 engaged with the cylindrical outer circumferential surface 102 of the stopper 66 is suppressed, the torque of the cam roller 62 in the direction of moving the lock member 42 back toward the unlock position is reduced, and the P release operation in which the parking pawl 40 slips off the parking ratchet 44 when the lock member 42 is moved back is suppressed. In this case, the stopper 66 is pressed between the cam roller 62 and the support member 30 to receive a pressing load, and therefore, the strength required for the stopper 66 and the locking member 42 is reduced as compared with the case where a bending load is applied as in the related art, enabling reduction in the size and weight of such components.The range L 1 of engagement between the stopper 66 located in the protruding position in the parking lock state and the support member 30 includes a portion (engagement point P 1) on the side of the unlocking position with respect to the rotation axis S 3 of the stopper 66 in the moving direction of the lock member 42. therefore, when a pushing-out force acts on the cam roller 62 to bias the lock member 42 toward the unlocking position, the rotation axis S 3 of the stopper 66 is shifted toward the parking pawl 40 when the position of the stopper 66 is varied using the engagement point P 1 as the rotation point. The displacement of the rotational axis S 3 pushes back the locking member 42 and the cam roller 62 toward the parking pawl 40, and the locking member 42 is substantially locked with the pushing-out force applied from the parking pawl 40, and the movement of the locking member 42 toward the unlocking position is prevented to further suitably prevent a P-releasing operation.The gap between the stopper 66 that is in the protruding position in the parking lock state and the support member 30, i.e., the gap between the engagement surface 104 aand the engagement surface 30 ais equal to or smaller than the gap between the guide roller 64 of the lock member 42 and the guide portion 94, both gaps being substantially zero in the first embodiment. Therefore, the stopper 66 is reliably pressed between the cam roller 62 and the support member 30 when a pressing-out force is applied to the cam roller 62, and the effect of suppressing the P releasing operation at the time when the vehicle is parked on a descending road is suitably achieved.The rotation axis S 3 of the stopper 66 and the axis S 1 of the cam roller 62 are located on the vertical line V 1 perpendicular to the moving direction of the locking member 42. Therefore, the stopper 66 is reliably pressed between the cam roller 62 and the support member 30 by a pushing-out force applied from the parking pawl 40, and the effect of suppressing the P releasing operation at the time when the vehicle is parked on a descending road is suitably achieved.The guide roller 64, which is engaged with the guide portion 94 and rolled to rotate to limit the displacement of the locking member 42 toward the opposite side of the parking pawl 40, is disposed on the locking member 42. Therefore, the lock member 42 is smoothly moved between the lock position and the unlock position by rotation of the cam roller 62 and the guide roller 64, the cam roller 62 being engaged with the cam surface 92, and the guide roller 64 being engaged with the guide portion 94. In this case, when a pushing-out force pushing the parking pawl 40 away from the parking ratchet 44 is generated when the vehicle is parked on a descending road, the pushing-out force slightly moves the lock member 42 toward the unlock position, which may cause a P-releasing operation. Therefore, a marked effect of suppressing the P releasing operation at the time when the vehicle is parked on a descending road is achieved by the provision of the stopper 66.Modifications of the first embodiment of the present invention will be described below. In the following modifications, portions substantially the same as those according to the first embodiment are given the same reference numerals to omit detailed description.FIG. 8 shows a region near the stopper 66 in the parking lock state according to a first modification of the first embodiment, and also shows an enlarged view of an engagement portion between the stopper 66 and the support member 30. An engagement surface 30 bprovided on the support member 30 is different from the engagement surface 30 aaccording to the first embodiment. The engagement surface 30 bis inclined with respect to a line parallel to the moving direction of the lock member 42, i.e., a line parallel to the guide portion 94, by an angle α 1 in the direction away from the rotation axis S 3 toward the lock position, which is the right direction in FIG. 8. The angle α 1 is, for example, in the range of about 0.5° to 2°, and is about 1° in the first modification. The engagement surface 104 aof the stopper 66 to be engaged with the engagement surface 30 bis parallel to the moving direction of the lock member 42 when the stopper 66 is in the protruding position, and is engaged with the engagement surface 30 bof the support member 30 only at the engagement point P 1 located on the side of the unlock position with respect to the rotation axis S 3. In the first modification, the engagement point P 1 serves as the engagement portion.With the first modification, the same function and effect as in the first embodiment can be obtained. That is, when the stopper 66 is pressed between the cam roller 62 and the support member 30 due to a pushing-out force, changes in the posture of the stopper 66 are restricted and the rotation of the cam roller 62 is suppressed, and the torque toward the rolling toward the unlocking position generated in the cam roller 62 by the pushing-out force is reduced to suppress a P releasing operation. Further, the engagement surface 30 bof the support member 30 is inclined in the direction away from the rotation axis S 3 toward the locking position. Therefore, when a pushing-out force acts on the cam roller 62 and the stopper 66 is pressed against the support member 30, a torque in the direction (counterclockwise in FIG. 8 ) in which the rotation axis S 3 of the stopper 66 is moved about the engagement point P 1 toward the locking position is generated based on the inclination of the engagement surface 30 bof the support member 30, and a force Fr toward the locking position is applied to the locking member 42 via the fastening pin 100 of the stopper 66. Therefore, movement of the lock member 42 toward the unlock position is prevented to further appropriately suppress a P release operation.FIG. 9 shows, like FIG. 8, a portion near the stopper 66 in the parking lock state according to a second modification of the first embodiment, and also shows an enlarged view of an engagement portion between the stopper 66 and the support member 30. An engagement surface 104 bprovided on the stopper 66 is different from the engagement surface 104 aaccording to the first embodiment in FIG. 7. the engagement surface 104 bis inclined with respect to a line parallel to the moving direction of the lock member 42, i.e., a line parallel to the guide portion 94, by an angle β 1 in the direction closer to the rotation axis S 3 toward the lock position, which is the right direction in FIG. 9. The angle β1 is in the range of about 0.5° to 2°, and is about 1° in the second modification. The engagement surface 30 aof the support member 30, which is to be engaged with the engagement surface 104 b, is parallel to the moving direction of the lock member 42 and is engaged with the engagement surface 104 bof the stopper 66 only at the engagement point P 1. In the second modification, the engagement point P 1 serves as an engagement portion.With the second modification, the same function and effect as in the first embodiment can be obtained. That is, when the stopper 66 is pressed between the cam roller 62 and the support member 30 due to a pushing-out force, changes in the posture of the stopper 66 are restricted and the rotation of the cam roller 62 is suppressed, and the torque toward the rolling toward the unlocking position generated in the cam roller 62 by the pushing-out force is reduced to suppress a P releasing operation. Further, the engagement surface 30 bof the support member 30 is inclined in the direction away from the rotation axis S 3 toward the locking position. Therefore, when a pushing-out force acts on the locking member 42 and the stopper 66 is pressed against the support member 30, a torque in the direction (counterclockwise in FIG. 9 ) in which the rotation axis S 3 of the stopper 66 is moved about the engagement point P 1 toward the locking position is generated based on the inclination of the engagement surface 30 bof the support member 30, and a force Fr toward the locking position is applied to the locking member 42 via the fastening pin 100 of the stopper 66. Therefore, movement of the lock member 42 toward the unlock position is prevented to further appropriately suppress a P release operation.FIG. 10 shows a third modification of the first embodiment, which is different from the first modification in FIG. 8 in that the engagement surface 104 aof the stopper 66 in the protruding position is caused to firmly contact the engagement surface 30 bof the support member 30 to be engaged in the predetermined engagement area L 1. That is, in the protruding position, a line perpendicular to the engagement surfaces 30 b, 104 aand passing through the rotation axis S 3 is inclined toward the unlocking position by an angle α 1 with respect to the vertical line V 1 perpendicular to an extension line of the guide portion 94 that is parallel to the moving direction of the locking member 42. Thus, even in the third modification, when a pushing-out force acts on the cam roller 62 and the stopper 66 is pressed against the support member 30, based on the inclination of the engagement surface 30 b, a force Fr toward the locking position is applied to the locking member 42, and a movement of the locking member 42 toward the unlocking position is prevented to appropriately suppress a P-releasing operation.Next, a second embodiment of the present invention will be described. FIG. 11 corresponds to FIG. 2 for the first embodiment and differs from the first embodiment in the relative arrangement position of the guide roller 64 with respect to the cam roller 62 and the stopper 66. the guide roller 64 is arranged on the relatively lower side in FIG. 11, i.e., at a position away from the support member 30. In this case, in the parking lock state illustrated in FIG. 11, that is, in the state where the stopper 66 takes the protruding position and engages with the support member 30, a gap C is formed between the guide roller 64 and the guide portion 94 of the support member 30, and when a pushing-out force is applied to the cam roller 62, the entire pushing-out force is received by the support member 30 via the stopper 66. Thus, the stopper 66 is reliably pressed between the cam roller 62 and the support member 30 by the pushing-out force, whereby a P releasing operation at the time when the vehicle is parked on a descending road is suitably suppressed.Next, a third embodiment of the present invention will be described. FIG. 12 shows a portion near a stopper 120 in the locked state. The stopper 120 integrally includes a guide roller 122 having the same diameter as the cylindrical outer circumferential surface 102. That is, the guide roller 122 in a cylindrical shape is integrally provided at a portion adjoining the protruding portion 104 in the axial direction of the stopper 120 or at a portion on the front side of the sheet surface of FIG. 12 in the third embodiment. On the other hand, the support member 30 is integrally provided with a guide portion 124 that abuts a recess provided with the engagement surface 30 a, the stopper guide surface 106, and the stopper abutment surface 108. The guide roller 122 is engaged with the guide portion 124, and is rolled to rotate when the locking member 42 is moved between the locking position and the unlocking position to limit the displacement of the locking member 42 toward the opposite side of the parking pawl 40. In this case, in addition to achieving the same function and effect as in the first embodiment, the number of components is reduced as compared with the case where the guide roller 64 and the stopper 66 are separately provided as in the first embodiment.Next, a fourth embodiment of the present invention will be described. FIG. 13 corresponds to FIG. 7 for the first embodiment and differs from the first embodiment in the arrangement position of the cam roller 62. that is, while the stopper 66 and the cam roller 62 are arranged such that the rotation axis S 3 of the stopper 66 and the axis S 1 of the cam roller 62 are positioned on the vertical line V 1 that is perpendicular to an extension line of the guide portion 94 extending in the moving direction of the lock member 42 in the first embodiment, the cam roller 62 is arranged such that the axis S 1 of the cam roller 62 is displaced by a dimension d toward the unlocking position with respect to the vertical line V 1 that passes through the rotation axis S 3 in the fourth embodiment. In this case, when an upward push-out force is applied to the cam roller 62 and the cam roller 62 is pressed against the cylindrical outer circumferential surface 102 of the stopper 66, a clockwise torque, i.e., in the moving direction of the locking member 42 toward the locking position, is generated in the cam roller 62 due to the positional displacement by the dimension d, thereby appropriately suppressing a P releasing operation.Next, a fifth embodiment of the present invention will be described. FIG. 14 is a front view illustrating a portion near the cam mechanism 96 in the parking lock state in an enlarged manner. FIG. 15 is a front view illustrating a portion near the cam mechanism 96 in the unlocked state in an enlarged manner. In the drawings, the outer circumferential surface of the cam roller 62 is provided with a fixing portion 130 that protrudes toward the locking position, i.e., the right direction in FIG. 14, in the locked state to be brought into contact with the locking-side engagement surface 40 aof the parking pawl 40 over a predetermined engagement length L 2. The attachment portion 130 has an isosceles triangular cross-sectional area cut along a plane perpendicular to the axis S 1, with two sides of the isosceles triangle protruding in the directions of tangents to the outer circumferential surface of the cam roller 62. One of both sides of the fixing portion 130 that does not contact the lock-side engagement surface 40 ais changeable as necessary, and may be provided, for example, so as to extend perpendicularly (in a direction of a normal line) to the outer circumferential surface. The dot-and-dash line indicated in the cam roller 62 is an auxiliary line indicating a perfect circle and drawn to make the protruding shape of the attachment portion 130 clear.In this case, when an upward pushing-out force in FIG. 14 is applied to the parking pawl 40, the lock-side engagement surface 40 aof the parking pawl 40 is pressed against the attachment portion 130 of the cam roller 62 by the pushing-out force, and sliding friction is caused at the contact portion. The rotational resistance caused before the cam roller 62 starts rolling increases due to the sliding friction and the rolling resistance. Therefore, a force in the direction of the rearward movement toward the unlocking position applied to the lock member 42 is reduced together with the rolling of the cam roller 62, and a P release operation in which the parking pawl 40 slides off the parking ratchet 44 when the lock member 42 is moved back is suppressed. That is, when the contact portion between the cam roller 62 and the lock-side engagement surface 40 ais elastically deformed due to the pushing-out force, the sliding friction is caused at the contact portion to increase the rotational resistance before the cam roller 62 is rolled and the fixing portion 130 is moved away from the lock-side engagement surface 40 a. The predetermined engagement length L 2 is appropriately determined in advance by an experiment etc. so that a targeted P-release suppressing effect is obtained, and is, for example, in the range of about 20% to 40% of the diameter of the cam roller 62.In the fifth embodiment, the rolling of the cam roller 62 itself is suppressed by the attachment portion 130 provided on the cam roller 62, and therefore, a P release operation at the time when the vehicle is parked on a descending road is suitably suppressed in addition to achieving the P release operation suppressing effect by the stopper 66 as in the first embodiment.

Claims

A vehicle parking lock mechanism (10) comprising: a parking ratchet wheel (44); a parking pawl (40) provided to be moved closer to and away from the parking ratchet wheel (44) and configured to engage the parking ratchet wheel (44) to prevent rotation of the parking ratchet wheel (44); a locking member (42) arranged to be moved reciprocally between a locking position and an unlocking position, the locking member (42) being configured to move the parking pawl (40) closer to the parking ratchet wheel (44) via a cam mechanism (96) when the locking member (42) is moved toward the locking position to establish a parking locked state in which the rotation of the parking ratchet wheel (44) is prevented by the parking pawl (40) when the locking member (42) is moved to the locking position; and a support member (30) disposed on an opposite side of the locking member (42) from the parking pawl (40) and provided with a guide portion (94) configured to:, in order to guide the movement of the locking element (42) between the locking position and the unlocking position and at the same time restrict the displacement of the locking element (42) towards the opposite side of the parking pawl (40), wherein the cam mechanism (96) comprises a cam roller (62) arranged on the locking element (42) so as to be rotatable about an axis (S1) at right angles to a direction of movement of the locking element (42) and a cam surface (92) provided on the parking pawl (40) so as to be engageable with the cam roller (62), wherein the cam mechanism (96) is configured such that the parking pawl (40) is moved closer to the parking ratchet wheel (44) so as to be engageable with the parking ratchet wheel (44), by engaging the cam surface (92) with the cam roller (62) when the locking member (42) is moved from the unlocked position to the locked position; and wherein in the vehicle parking lock mechanism (10), the locking member (42) includes a stopper (66, 120) disposed on the locking member (42) to be rotatable about a rotation axis (S3) parallel to the axis (S1) of the cam roller (62) and having a cylindrical outer circumferential surface (102) to be brought into rolling contact with an outer circumferential surface of the cam roller (62), wherein the stopper (66, 120) is rotated about the rotation axis (S3) together with the rotation of the cam roller (62) about the cylindrical outer circumferential surface (102) when the locking member (42) is moved from the unlocked position toward the locked position, to be engaged with the support member (30) by taking a protruding position in which the stopper (66, 120) protrudes toward the support member (30) in the parking lock state.The vehicle parking lock mechanism (10) according to claim 1, wherein a gap between the stopper (66) and the support member (30) is equal to or smaller than a gap between the lock member (42) and the guide portion (94), the stopper (66) being in the protruding position in the parking lock state.The vehicle parking lock mechanism (10) according to claim 1 or 2, wherein the stopper (66) is disposed on the lock member (42) such that the rotation axis (S3) and the axis (S1) of the cam roller (62) are on a line perpendicular to the moving direction of the lock member (42).The vehicle parking lock mechanism (10) according to any one of claims 1 to 3, wherein an engagement portion of the stopper (66) in the protruding position for engagement with the support member (30) includes a portion on a side of the unlocking position with respect to the rotation axis (S3) in the moving direction of the lock member (42).The vehicle parking lock mechanism (10) according to claim 4, wherein an engagement surface (30a) on a side of the support member (30) to be engaged with the stopper (66) on the engagement portion is inclined toward the lock position with respect to a line parallel to the moving direction of the lock member (42) in a direction away from the rotation axis (S3).The vehicle parking lock mechanism (10) according to claim 4, wherein an engagement surface (30a) on a side of the stopper (66) to be engaged with the support member (30) at the engagement portion is inclined toward the lock position in a direction closer to the rotation axis (S3) with respect to a line parallel to the moving direction of the lock member (42).The vehicle parking lock mechanism (10) according to any one of claims 1 to 6, wherein the outer circumferential surface of the cam roller (62) is provided with a fixing portion (130) that protrudes toward the lock position in the parking lock state to be brought into contact with the parking pawl (40) over a predetermined engagement length (L2).The vehicle parking lock mechanism (10) according to any one of claims 1 to 7, wherein the lock member (42) is provided with a guide roller (122) to be engaged with the guide portion (124) and rolled to rotate when the lock member (42) is moved between the lock position and the unlock position to restrict displacement of the lock member (42) toward the opposite side of the parking pawl (40).

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