DRIVE PLATE FOR A VEHICLE

Abstract: The drive plate (10) comprises: a mounting portion (11) to be connected with the crankshaft (1); a ring gear (10a) to be meshed with a starter; a plurality of additional holes (14) for lightening the weight of the drive plate (10); and a plurality of bolt holes (13) to be inserted with bolts (3) connecting the drive plate (10) with the torque converter (5). In the drive plate (10), an outer edge (14c) of each of the additional holes (14) is formed by a line, and the line is substantially in parallel to a straight line (A) which is in contact with contours of adjacent seat surfaces (13a) of the bolt holes (13).

Description: DESCRIPTION DRIVE PLATE FOR A VEHICLE Technical field The present invention relates to a drive plate for a vehicle disposed between a crankshaft of an automotive engine and a torque converter. Background Art As a drive plate connecting a crankshaft of an automotive engine and a torque converter, there has been known a structure shown in Japanese Patent Unexamined Application Laid Open No. 8-105504. The drive plate is formed to have a disc shape in an outer appearance from a metal plate, and a ring gear for a starter is mounted to an outer peripheral portion thereof . A plurality of bolt holes are provided in a center portion of the plate for being mounted to the crankshaft , and a plurality of bolt holes are provided in an outer peripheral portion of the plate for being mounted to the torque converter. These bolt holes are respectively disposed in the center portion of the plate and the outer peripheral portion of the plate at a constant interval on the same circumference of a circl . A plurality of additional holes are disposed in the center portion of the plate at the same angular position as that of the bolt holes to the circular direction. A tongue-like flange projecting to an inner diameter is formed in the outer peripheral portion of the plate by the additional holes , so that each of the bolt holes is open to a portion closer to the center portion of the plate than the outer peripheral position of the additional holes. The center portion of the plate is drawn so that a through hole is formed in a bottom portion thereof. The drive plate is fastened to a rear end surface of the crankshaft through the bolt hole disposed in the center portion thereof by the bolt extending therethrough. With respect to the torque converter, it is fastened to the boss portion thereof through the bolt hole disposed in the outer peripheral portion of the plate by the bolt extending therethrough. Rotation is transmitted between the crankshaft of the automotive engine and the torque converter through the drive plate. When a load in a thrust direction is applied from the torque converter, the center portion of the plate is hardly displaced because of its high rigidity, so that the outer portion is bent, however, since the displacing distance extends to the outer diameter side from the bolt hole due to the additional hole forming the flange, a bending stress to the periphery of the center portion of the plate becomes small, so that an effect of preventing the breakage can be obtained. In this case, the drive plate can be lightened by the additional hole and the through hole. However, since the additional hole does not have an optimum shape against the load to the radial direction (a torsional direction), it is necessary to make a thickness thereof large and make the additional hole small in order to secure a strength. If doing so, as a matter of course, the weight increase is invited. Further, since the rigidity becomes high, the load to the thrust direction from the torque converter can not be sufficiently reduced, so that a stick or seizure or the like by frictional heating is easily generated in the thrust metal. Disclosure of Invention The present invention has been achieved with such points in view. It therefore is an object of the present invention to provide a drive plate for a vehicle capable of lightening of the weight of drive plate at a maximum level while securing and sustaining the optimum rigidity and strength. To achieve the object, according to an aspect of the present invention provides a drive plate for a vehicle mounted between a crankshaft of an automotive engine and a torque converter, comprising: a mounting portion to be connected with the crankshaft , the mounting portion located in a center portion of the plate; a ring gear to be meshed with a starter, the ring gear formed in an outer peripheral portion of the plate; a plurality of additional holes for lightening the weight of the drive plate, the additional holes located in a center portion between the mounting portion and the ring gear at a constant interval to a circumferential direction; and a plurality of bolt holes to be inserted with bolts connecting the drive plate with the torque converter, the bolt holes formed in an outer side of each of the additional holes , the bolt holes having a plurality of seat surfaces pressed by the bolts, wherein an outer edge of each of the additional holes is formed by a line; and the line is substantially in parallel to a straight line which is in contact with contours of the adjacent seat surfaces from the outer portion. In accordance with the aspect of the present invention, the stress generated in the drive plate becomes the largest in the direction between the seat surfaces of the adjacent bolts with respect to the load to the torsion direction, however, since the line substantially in parallel to the straight line is formed in the outer edge of the additional hole, the generated stress can be averaged. Accordingly, the area of the additional hole can be secured to be wide while the maximum stress between the seat surfaces of the bolts can be restricted in a small level. Brief Description of Drawings The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read in conjunction with the accompanying drawings, in which: Fig. 1 is an elevation view, partially in section of a portion of a crankshaft and transmission showing the drive plate of the present invention; Fig. 2 is a front elevational view which shows the drive plate in accordance with first embodiment of the present invention; Fig. 3 is a front elevational view which shows the drive plate in accordance with a modified second embodiment of the additional hole; Fig. 4 is an enlarged front elevational view of the additional hole of the second embodiment; and Fig. 5 is a front view which shows the additional hole of the drive plate in accordance with a modified third embodiment . Best Mode for Carrying Out the Invention There will be detailed below the preferred embodiments of the present invention with reference to the accompanying drawings . Like members are designated by like reference characters. Referring now to the drawings , Figs . 1 and 2 show an embodiment of a drive plate 10 for a automotive vehicle according to the invention. The drive plate 10 is mounted between a crankshaft 1 and a torque converter assembly 5 as shown in Fig.l. The drive plate 10 is formed to have a disc shape in an outer appearance from a metal plate, and a ring gear 10a for a starter is mounted to an outer peripheral portion thereof. A mounting portion 11 to the crankshaft 1 is provided in the center portion of the drive plate 10. The mounting portion 11 is drawn and a through hole 12 is formed in a center portion of a bottom surface thereof. A plurality of bolt holes 11a are provided in a periphery of the through hole 12 disposed on the same circumference of a circle at a constant interval. A plurality of bolt holes 13 for being mounted to the torque converter 5 are formed in the outer peripheral portion of the plate in such a manner as to be disposed on the same circumference of a circle at a constant interval in the same manner as that of the bolt holes 11a. Referring now back to the Figs . 1 , the drive plate - 10 is connected to the crankshaft 1 by bolts 2 through the bolt holes 11a. The drive plate 10 is also connected to a cover member 4 of the torque converter 5 by bolts 3 through the bolt holes 13. The cover member 4 is formed with a protrusion portion 6 at the center thereof. The protrusion portion 6 is axially slidably inserted into a concave portion of the crankshaft 1 through a cylindrically shaped metal 7. A plurality of additional holes 14 are disposed in the center portion of the plate to the circumferential direction at a constant interval as shown in Fig. 2. Each of the additional holes 14 is formed as a substantially triangular shape symmetrical with respect to a center axis on a straight line C connecting the center of the bolt hole 13 and the center of the drive plate 10, and a projecting portion 14a to the outer periphery of the plate is provided in both sides of a bottom line thereof. A tongue-like flange 15 projecting to the inner diameter of the plate is formed by the projecting portion 14a, so that the bolt hole 13 is open to each of the flanges 15 as shown in Fig. 2. In addition to the additional hole 14 and the through hole 12, a circular hole 16 for lightening is formed. The circular hole 16 is disposed one by one in the center position of the adjacent additional holes 14. In this case, both side edges of the additional hole 14 are formed by a line 14b extending to a direction substantially perpendicular to the straight line B connecting the center of the circular hole 16 and the center of the bolt hole 13. Further, a front end of the projecting portion 14a is formed in a line 14c substantially in parallel to the straight line A which is in contact with a contour of seat surfaces 13a of the adjacent bolts in a direction from the outer portion of the drive plate 10. The seat surfaces 13a are provided at circumferences portions of the bolt holes 13 respectively, and to be pressed by the bolts 3 and the cover member 4. In order to reduce the stress concentration, each of the corner portions of the additional holes 14 is smoothened. Among these, with respect to both end corner portions of the line 14c substantially in parallel to the straight line A, a radius Rl of curvature of the corner portion close to the bolt hole 13 is set to be larger than a radius R2 of curvature of the portion apart from the bolt hole 13 in correspondence to the distance with respect to the bolt hole 13. Further, an interval having a distance L ≤≥ 0 is provided between the center portion of the plate (the mounting portion 11 to the crankshaft 1) and the additional hole 14. The drive plate 10 is fastened to a rear end surface of the crankshaft 1 through the bolt hole disposed in the center portion thereof by a bolt extending therethrough. With respect to the torque converter, it is fastened to a boss portion thereof through the bolt hole 13 disposed in the outer peripheral portion of the plate by a bolt extending therethrough. Rotation is transmitted between the crankshaft of an automotive engine and the torque converter through the drive plate 10. When the load is applied to the thrust direction from the torque converter, the center portion of the plate is hardly displaced because of its high rigidity, so that the outer side thereof is bent. Since the flange 15 absorbs the bending, a bending angle that the outer side is bend around the periphery of the center portion of the plate becomes small and the generated stress is averaged in correspondence to the interval distance L, so that the breakage in the periphery of the center portion of the plate can be efficiently prevented. With respect to the load to the thrust direction, in the projecting portion 14a of the additional hole 14, the stress concentration becomes larger in the corner portion close to the bolt hole 13, however, when the radii Rl and R2 of curvature of these corner portions are set such that one close to the bolt hole 13 becomes larger, the stress to both side corner portions of the line 14c forming the outer edge of the additional hole 14 can be reduced on the average . The drive plate 10 receives the load to the torsion direction between the crankshaft and the torque converter due to the rotational change therebetween. The generated stress of the drive plate 10 becomes the largest in the direction between the bolt seat surfaces 13a due to the load to the torsion direction, however, the stress generated in the portion can be averaged by forming the front end 14c of the projecting portion 14a substantially in parallel to the straight line A. In the case that the front end 14c of the projecting portion 14a is inclined to the straight line A as in the conventional art, when a position of the front end of the projecting portion 14a is not changed, an area of the additional hole 14 becomes small at a degree of the inclined amount with respect to the straight line A. In other words , by forming the front end 14c of the projecting portion 14a substantially in parallel to the straight line A, the area of the additional hole 14 can be efficiently enlarged while restricting the stress generated in the portion to a small level . With respect to the load to the torsion direction, between the additional holes 14, the response becomes highest on the straight line B by the effect of the circular hole 16, however, since both side edges of the additional holes 14 are formed by the line 14b extending to the direction substantially perpendicular to the straight line B, the area of the additional hole 14 can be efficiently enlarged while securing a width E of the portion having the highest stress (the strength against the load to the torsion direction) on the basis of the same reason as that of the front end 14c of the projecting portion 14a. As a result of this, the drive plate 10 can be lightened for the weight thereof in a maximum manner while securing and sustaining the optimum rigidity and strength. Referring now to Figs . 3 and 4 , a second embodiment of the invention will be described hereinafter. The drive plate 10 of the second embodiment is formed with additional holes 114. Each of the he additional holes 114 is formed as a substantially triangular shape symmetrical with respect to the center axis on the straight line C shown in Fig. 2 connecting the center of the bolt hole 13 and the center of the drive plate 10, and a projecting portion 114a to the outer periphery of the plate is provided in both sides of a bottom line thereof. A tongue-like flange 115 projecting to the inner diameter of the plate is formed by the projecting portion 114a, so that the bolt hole 13 is open to each of the flanges 115 as shown in Figs. 3 and 4. In addition to the additional hole 114 and the through hole 12, a circular hole 16 for lightening is formed. The circular hole 16 is disposed one by one in the center position of the adjacent additional holes 114. In this case , both side edges of the additional hole 114 are formed by a line 114b extending to a direction substantially perpendicular to the straight line B connecting the center of the circular hole 16 and the center of the bolt hole 13 as same as the first embodiment. Further, a front end of the projecting portion 114a is formed in a line 114c almost or substantially in contact with the straight line A which is in contact with a contour of the seat surfaces 13a of the adjacent bolts from the outer portion. Furthermore, the line 114c is located inner of the straight line A in the location between the line A and B, desirably. In order to reduce the stress concentration, each of the corner portions of the additional holes 114 is smoothened. Among these, with respect to both end corner portions of the line 114c substantially in parallel to the straight line A, a radius Rl of curvature of the corner portion close to the bolt hole 13 is set to be larger than a radius R2 of curvature of the portion apart from the bolt hole 13 in correspondence to the distance with respect to the bolt hole 13 as same as the first embodiment. In other wards, as to the additional hole 114, the front end 114c of the projecting portion 114a is formed in the portion close to the inner diameter than the straight line A and the additional hole on the straight line A is omitted, so that the generated stress of the line 114c substantially in parallel to the straight line A can be largely reduced. Referring now to Fig. 5, a third embodiment of the invention will be described hereinafter. The drive plate 10 of the third embodiment is formed with additional holes 214. Since the structure is made such as not to have the projecting portion 214a to the outer periphery of the plate, with respect to the load to the thrust direction, it is disadvantageous in view of the absorbing performance of the bending amount of the plate, however, by giving the same conditions as those mentioned above such as forming the line 214c substantially in parallel to the straight line A shown in Fig. 3, forming the line 214b substantially perpendicular to the straight line B shown in Fig. 3 and the like, the effect that the lightening of the drive plate 10 can be promoted while securing the optimum rigidity and strength can be obtained. Reference numeral 13 in the drawing denotes a bolt hole in the outer peripheral portion of the plate. As described hereinbefore, according to a first aspect of the present invention provides a drive plate for a vehicle mounted between a crankshaft of an automotive engine and a torque converter, comprising: a mounting portion to be connected with the crankshaft, the mounting portion located in a center portion of the plate; a ring gear to be meshed with a starter, the ring gear formed in an outer peripheral portion of the plate; a plurality of additional holes for lightening the weight of the drive plate, the additional holes located in a center portion between the mounting portion and the ring gear at a constant interval to a circumferential direction; and a plurality of bolt holes to be inserted with bolts connecting the drive plate with the torque converter, the bolt holes formed in an outer side of each of the additional holes , the bolt holes having a plurality of seat surfaces pressed by the bolts, wherein an outer edge of each of the additional holes is formed by a line; and the line is substantially in parallel to a straight line which is in contact with contours of the adjacent seat surfaces from the outer portion. In accordance with the first aspect of the present invention, the stress generated in the drive plate becomes the largest in the direction between the seat surfaces of the adjacent bolts with respect to the load to the torsion direction, however, since the line substantially in parallel to the straight line is formed in the outer edge of the additional hole, the generated stress can be averaged. Accordingly, the area of the additional hole can be secured to be wide while the maximum stress between the seat surfaces of the bolts can be restricted in a small level. According to a second aspect of the present invention, as it depends from the first aspect, the line of the additional hole is located inner side of the straight line. In accordance with the second aspect of the present invention, since the line substantially in parallel to the straight line of the additional hole is formed in the inner diameter side of the plate with respect to the load to the torsion direction and the additional holes on the straight line are omitted, the generated stress can be greatly reduced. According to a third aspect of the present invention , as it depends from the first or the second aspect, the drive plate for a vehicle according to claim 1 , further comprises : a circular hole formed in a center position between the adjacent additional holes, wherein both side edges of the additional holes are formed by a line extending to a substantially perpendicular direction to a second straight line connecting the center of the circular hole and the center of the bolt hole. In accordance with the third aspect of the present invention, the stress generated in the drive plate becomes the largest on the second straight line by an effect of the circular hole, however, since both side edges of the additional hole is formed by the line extending to the direction substantially perpendicular to the second straight line, the area of the additional hole can be enlarged in the maximum manner as well as the effect of the line substantially in parallel to the straight line while securing the width required with respect to the circular hole (the portion having the highest stress). According to a fourth aspect of the present invention , as it depends from one aspect among the first aspect to the third aspect , both end corner portions of the line substantially in parallel to the straight line of the additional holes is formed as a circular arc shape; and a radius of curvature of these corner portions is set in such a manner that as to become larger radius of the end corner portion as the corner portion becomes close to the bolt hole. In accordance with the fourth aspect of the present invention, with respect to the load to the thrust direction, in both side corner portions of the line substantially in parallel to the straight line of the additional hole, a stress concentration becomes larger as the corner portion becomes close to the bolt hole, however, since the radius of curvature of the corner portions is set to be larger as it is close to the bolt hole, the stress to both side corner portions of the line forming the outer side edge of the additional hole can be reduced on the average. According to a fifth aspect of the present invention, as it depends from one aspect among the first aspect to the fourth aspect, an interval having a distance L ≤≥ 0 is set between the mounting portion to be connected with the crankshaft and each of the additional holes. In accordance with the fifth aspect of the present invention, with respect to the load to the thrust direction. the outer side around the periphery of the center portion of the plate is going to bend, however, the bending stress to the periphery of the center portion of the plate can be averaged in response to the distance L of the interval between the center portion of the plate and the additional hole. Accordingly, the largest stress around the mounting portion to the crankshaft can be reduced. While preferred embodiments of the present invention have been described using specific terms , such description is for illustrative purposes, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims . Industrial Applicability As stated hereinbefore, the drive plate according to the invention is applicable for use in automotive vehicle, especially for a drive plate mounted between a crankshaft and a torque converter assembly, and used for a flywheel as well as for a flexplate flywheel.

Claims: CLAIMS 1. A drive plate for a vehicle mounted between a crankshaft of an automotive engine and a torque converter, comprising: a mounting portion to be connected with the crankshaft, the mounting portion located in a center portion of the plate ; a ring gear to be meshed with a starter, the ring gear formed in an outer peripheral portion of the plate; a plurality of additional holes for lightening the weight of the drive plate , the additional holes located in a center portion between the mounting portion and the ring gear at a constant interval to a circumferential direction; and a plurality of bolt holes to be inserted with bolts connecting the drive plate with the torque converter, the bolt holes formed in an outer side of each of the additional holes , the bolt holes having a plurality of seat surfaces pressed by the bolts, wherein an outer edge of each of the additional holes is formed by a line; and the line is substantially in parallel to a straight line which is in contact with contours of the adjacent seat surfaces from the outer portion. 2. A drive plate for a vehicle according to claim 1, wherein the line of the additional hole is located inner side of the straight line. 3. A drive plate for a vehicle according to claim 1, further comprising: a circular hole formed in a center position between the adjacent additional holes, wherein both side edges of the additional holes are formed by a line extending to a substantially perpendicular direction to a second straight line connecting the center of the circular hole and the center of the bolt hole. 4. A drive plate for a vehicle according to claim 1 , wherein both end corner portions of the line substantially in parallel to the straight line of the additional holes is formed as a circular arc shape; and a radius of curvature of these corner portions is set in such a manner that as to become larger radius of the end corner portion as the corner portion becomes close to the bolt hole. 5. A drive plate for a vehicle according to claim 1 , wherein an interval having a distance L ≤≥ 0 is set between the mounting portion to be connected with the crankshaft and each of the additional holes .

Inventors: OGIHARA OSAMU, OGIHARA, OSAMU
Applicants: NISSAN MOTOR, OGIHARA OSAMU, NISSAN MOTOR CO., LTD., OGIHARA, OSAMU
Application year: 1998
Main classification: F16H41
IPC codes: F16D1, F16D3, F16H41