Automatic transmission shift control device

Abstract: A position pin (20) is pushed down by an effort applied on a control button (27) to disengage the position pin (20) from a position plate (18) when a selector lever is to be moved from a parking position to other gear positions. A bushing (28) is mounted on a post (14) of the selector lever for rotation but against axial movement. The bushing has at the upper end a pair of diameterically opposed notches (29) with which the position pin is engaged when pushed down to effect the above disengagement. When an ignition key is at the "ON" position and the selector lever is at the parking position, the bushing is rotated into a position where the notches are misaligned with the position pin unless a brake pedal is fully depressed, i.e., an effor applied on the control button for pushing the position pin downward is received by the upper end of the bushing whereby downward movement of the position pin for disengagement thereof from the position plate is prevented by the bushing and therefore it is impossible to move the selector lever from the parking position to other gear positions. In accordance with the present invention, there are further provided various safety means for preventing the positon pin from being errorneously aligned with the notches.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates in general to automatic transmissions and more particularly to an automatic transmission shift control device of the kind in which when the ignition key is at the "ON" position, shifting of gears from "P(parking)" to other gears cannot be attained unless the brake pedal is fully depressed. 2. Description of the Prior Art An example of an automatic transmission shift control device of the above described kind is shown in JP-U-60-185750. From this document an automatic transmission shift control device for a vehicle having a brake pedal is known, comprising a selector lever movable into a plurality of gear positions including a parking position, and having a hollow cylindrical post, having a pair of diametrically opposed openings and a knob attached to the upper end of said post, and selector lever shift position control means for controlling movement of said selector lever, said selector lever shift position control means including a position plate having a profiled opening defining said gear position, a position pin installed transversely of said post in said openings for up-and-down movement and releaseably engaged in said position plate for positioning said selector lever at one of said gear positions, a rod installed in said post for up-and-down movement and supporting said position pin at the lower end thereof, a control button mounted in said knob for substantially horizontal movement and cooperative with said rod to disengage said position pin from said position plate. A problem of the prior art shift control device is that the solenoid pin of solenoid is liable to be deformed to cause malfunction of the shift control device since if the selector lever in a locked condition is operated for shifting gears, the solenoid pin receives the operating force to resist against movement of the selector lever. In order to solve this problem, the solenoid pin may be increased in strength so as not to be deformed by such an operating force. But this causes another problem that the solenoid is large-sized to increase the manufacturing cost, weight and the design and layout restrictions. From EP-A-300 268, which is a document published after the priority date of the present application, an automatic transmission shift control device for a vehicle having a brake pedal is known, comprising: a selector lever movable into a plurality of gear positions including a parking position having a hollow cylindrical post, having a pair of diametrically opposed openings and a knob attached to the upper end of said post, selector lever shift position control means for controlling movement of said selector lever, said selector lever shift position control means including a position plate having a profiled opening defining said gear position, a position pin installed transversely of said post in said openings for up-and-down movement and releasably engaged in said position plate for positioning said selector lever at one of the gear positions, a rod installed in said post for up-and-down movement and supporting said position pin at the lower end thereof, a control button mounted in said knob for substantially horizontal movement and cooperative with said rod to disengage said position pin from said position plate, a bushing mounted on said post for rotation but against axial movement and having at the upper end a pair of diametrically opposed notches with which said position pin is engaged for disengaging said position pin from said position plate, a solenoid operatively connected to said bushing to rotate same selectively between a first position where notches are aligned with said position pin and a second position where said notches are misaligned with said position pin, said solenoid being operative in such a way that said bushing is rotated into said first position when said position pin is at said parking position and the brake pedal is fully depressed and into said second position when said position pin is at said parking position and the brake pedal is free from depression, and safety means for preventing said position pin from being erroneously aligned with said notches. It is an object of the present invention to provide an improved automatic transmission shift control device, which is assuredly prevented from malfunction caused by erroneous or unintended movement of a bushing and by deformation or damage of a solenoid pin and other constituent parts. The solution to this problem is achieved by the features of Claim 1 and Claim 4, respectively. In accordance with the present invention there is provided an automatic transmission shift control device for a vehicle having a brake pedal, wherein said safety means comprising limiting means, wherein said bushing has at the upper end thereof a pair of axial projections which are arranged on one side of said respective notches, said selector lever shift position control means further including a bushing support secured to said post and supporting thereon said bushing, and a stopper installed on said post in the place above said bushing so that said bushing abuts at the projections upon said stopper when upward movement of said bushing reaches a predetermined amount, said projections and said stopper constituting said limiting means, wherein the distance l₁ between each of said projections and said stopper is determined so as to satisfy the relation of l₁ ≦ than l₂ where l₂ is the distance between said upper end of said bushing and the position pin in its highest possible position. Alternatively thereto said bushing has a radially projecting arm pin which is formed with a slot and said solenoid has a solenoid pin engaged at an end in said slot, wherein said end of said solenoid pin is bent vertically downward to constitute a vertical portion engaged in said slot, said solenoid pin further having a horizontal portion located above said arm so that said arm abuts upon said horizontal portion when upward movement of said bushing reaches a predetermined value, said solenoid pin and said arm constituting said limiting means, wherein the distance l₁ between said horizontal portion and said arm is determined so as to satisfy the relation of l l ≦ l₂, where l₂ is the distance between said position pin in its highest possible position and said upper end of said bushing when said bushing is in contact with said bushing support. The subclaims contain preferred embodiments of the present invention. With the present invention there is furthermore achieved an improved automatic transmission shift control device which can effectively prevent its constituent part or parts from being damaged without increasing the strength of each constituent part of itself. Furthermore, the present invention provides an improved automatic transmission shift control device of the above described character which does not require a solenoid to be large-sized and therefore does not increase the manufacturing expense, weight and the design and layout restrictions. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional, partly omitted, view of an automatic transmission shift control device according to an embodiment of the present invention; Fig. 2 is a view taken in the direction of the arrow II of Fig. 1; Fig. 3 is a view taken in the direction of the arrow III of Fig. 2; Fig. 4 is a cross sectional view of the embodiment Fig. 1 but showing the shift control device in another operative position; Fig. 5 is an elevational, partly omitted, view of a post and a position pin employed in the embodiment of Fig. 1; Fig. 6 is a view taken in the direction of the arrow VI of Fig. 1; Fig. 7 is a perspective view of a bushing employed in the embodiment of Fig. 1; Fig. 8 is a view similar to Fig. 2 but showing a variant of the embodiment of Fig. 1; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Figs. 1 to 7, an automatic transmission shift control device according to an embodiment of the present invention is shown as comprising a selector lever 10 and a selector lever shift position control means 12 for controlling the movement of the selector lever 10. The selector lever 10 is swingable into various gear positions including a "P" position for shifting gears of an associated automatic transmission (not shown). The selector lever 10 consists of a hollow cylindrical post 14 pivotally mounted at the lower end on a vehicle body 15 and a knob 16 attached to the upper end of the post 14. The selector lever shift position control means 12 includes a position plate 18 which is stationary, i.e., fixedly attached to the vehicle body 15. As shown in Fig. 6, the position plate 18 is formed with a profiled opening 18a for locating the selector lever 10 in various gear positions including a "P" position. A position pin 20 is engaged in the profiled opening 18a of the position plate 18 for positioning the selector lever 10 at one of the gear positions. The hollow cylindrical post 14 is formed with a pair of diametrically opposed openings 22 and 22 for receiving therein the position pin 20. The openings 22 and 22 are elongated axially of the post 14 for allowing up-and-down movement of the position pin 20 relative to the post 14 and the position plate 18. The position pin 20 extends across the post 14 and has opposite ends projecting outwardly from the openings 22 and 22. A rod 24 is installed in the post 14 for up-and-down movement and attached to the position pin 20 at the lower end. More specifically, the lower end of the rod 24 is attached to a slider 21 which is slidably received within the post 14 and movable together with the position pin 20. A slide cam 26 having a tapered cam face 26a is installed in the knob 16 and attached to the upper end of the rod 24 for up-and-down movement with same. A coil spring 25 is installed in the post 14 to urge the rod 24 and the slide cam 26 upwardly together with the position pin 20. A control button 27 is installed in the knob 16 for substantially horizontal movement and has an inner end portion 27a engaged with the tapererd cam surface 26a so that pushing the control botton 27 into the knob 16 or allowing the former to project outwardly from the latter causes downward movement or upward movement of the slide cam 26 and the rod 24. A bushing 28 has a hollow cylindrical shape as shown in Fig. 7 and is concentrically mounted on the post 14 for rotation but against axial movement. The bushing 28 has at an upper end portion a pair of diametrically opposed notches 29 and 29 with which the position pin 20 is engaged when the selector lever 10 is moved from the "P" position into other gear positions as the "R (reverse)" position, "N(neutral)" position, "D (drive)" position, "1(first gear)" position and the "2(second gear)" position. In other words, in order to shift the selector lever 10 from the "P" position to other gear positions it is necessary to move the position pin 20 into the lower end portions of the openings 22 and 22. To attain this, it is inevitable for the position pin 20 to be moved into the notches 29 and 29. A solenoid 30 is installed on the post 14 by means of a bracket 23 and connected to the bushing 28 for controlling the position thereof as follows. That is, when the position pin 20 is at the "P" position and the brake pedal is not depressed, the bushing 28 is rotated into a selector lever locking position where the notches 29 and 29 are misaligned with the position pin 20 as shown in Fig. 4. When the brake pedal is fully depressed to cause a stop switch (not shown) to be turned on and thereby energize the solenoid 30, the bushing 28 is moved from the selector lever locking position into a selector lever unlocking position where the notches 29 and 29 are aligned with the position pin 20 as shown in Fig. 2. Indicated by the reference numeral 34 is a solenoid pin projectable from and retractable into the solenoid 30 and has an end 34a engaged in a slot 36 formed in an outer peripheral projection or radially projecting arm 38 of the bushing 28. Indicated by the reference numeral 40 is a bushing support welded or otherwise secured to the post 14 for supporting thereon the bushing 28. The selector lever shift position control means 12 further includes a limiting means 42 for limiting upward movement of the bushing 28. The limiting means 42 consists of a pair of axial projections 43 and 43 provided to the upper end 28a of the bushing 28 and a stopper 46 installed on the post 14. More specifically, the projections 43 and 43 are arranged on one side of the notches so that the position pin 20 is swingable between two position where it is aligned and misaligned with the notches 29 and 29. The stopper 46 is arranged above the bushing 28 so as to abut upon the projections 43 and 43 when upward movement of the bushing 28 reaches a predetermined amount for thereby limiting upward movement of the bushing 28. The stopper 46 may be a snap ring or the like. In the meantime, the distance ℓ₁ between each projection 43 and the stopper 46 and the distance ℓ₂ between the upper end 28a of the bushing 28 and the position pin 20 in its highest possible position are designed so as to satisfy the relation of ℓ₁ ≦ ℓ₂ when the bushing 28 is in contact with the bushing support 40. With the foregoing structure, when an ignition key (not shown) is at the "ON" position, shifting of the selector lever 10 from the "P" position to other gear positions is prevented as follows unless a brake pedal (not shown) is fully depressed. When the ignition key is at the "ON" position and the brake pedal is not fully depressed, the solenoid 30 is energized to allow the solenoid pin 34 to project outwardly therefrom. By this, the bushing 28 is rotated into the selector lever locking position where the notches 29 and 29 are misaligned with the position pin 20. In order to shift the selector lever 10 from the "P" position to other gear positions as "R", "N", "D", "2" and "1", it is necessary to push the control button 27 into the knob 16 for thereby pushing the position pin 20 down into its lowest possible position, i.e., into the lower end portions of the openings 22 and 22 so that the position pin 20 can clear a stopper portion 18b of the profiled opening 18a of the position plate 18. However, the downward movement of the position pin 20 in response to the pushing of the control button 27 inwardly of the knob 16 is prevented by the bushing 28, i.e., the control button 27 cannot be pushed into the knob 16 sufficiently or by a predetermined amount since the notches 29 and 29 are misaligned with the position pin 20 to make the position pin 20 abut upon the upper end 28a of the bushing 28. In the above, it will be understood that in order to prevent shifting of gears from the "P" position to other gear positions when the brake pedal is not depressed, it is only necessary to rotate, by the operation of the solenoid 30, the bushing 28 from the selector lever unlocking position to the selector lever locking position. A required power for attaining the selector lever shift position control can therefore be considerably smaller as compared with that required by the prior art device. Accordingly, the solenoid 30, the bushing 28, etc. can be compact in size, thus making it possible to reduce the cost and weight. It will be further understood that the force with which the position pin 20 is subjected during the above prevention of gear shifting is sufficiently small since the position pin 20 receives only the force which is transferred from the control button 27 through the slide cam 26. The force applied to the control button 27 is not so large. Further, the force received by the position pin 20 is smaller than the force applied to the control button 27 since it is reduced during transmission from the control button 27 to the slide cam 26 by the effect of the tapered cam surface 26a. In order to shift the selector lever 10 from the "P" position to other gear positions, the brake pedal is fully depressed. When the brake pedal is fully depressed, the solenoid pin 34 is deenergized and thus retracts into the solenoid 30, rotating the bushing 28 into the selector lever unlocking position where the notches 29 and 29 are aligned with the position pin 20. Pushing the control button 27 into the knob 16 causes movement of the position pin 20 into the lower end portions of the openings 22 and 22, whereby to make it possible for the position pin 20 to clear the stopper portion 18b of the profiled opening 18a of the position plate 18. The selector lever 10 therefore can be moved from the "P" position to other gear positions. It is to be noted that by the provision of the limiting means 42 for limiting upward movement of the bushing 28 the bushing 28 can be assuredly rotated between the above described two positions by the operation of the solenoid 30, thus increasing the reliability of operation of the selector lever shift position control means 12. That is, the bushing 28 may move upwards in response to upward movement of the position pin 20 and vibrations of the vehicle body. When the upward movement of the bushing 28 reaches a predetermined amount, the position pin 20 in its highest possible position, i.e., in the position engaged in the upper end portion of the openings 22 and 22, can engage in the notches 29 and 29. When this is the case, it is impossible to rotate the bushing 28 from the selector lever unlocking position to the selector lever locking position even if the soleoid 30 is actuated and tries to do so, thus causing a malfuction of the selector lever shift position control means 12, i.e., making it possible, even if the brake pedal is not depressed, to shift the selector lever 10 from the "P" position to any other gear positions. However, by the provision of the limiting means 42, the projections 43 and 43 of the bushing 28 are brought into abutment upon the stopper 46 when the bushing 28 moves the distance ℓ₁ upwardly, thus limting the upward movement of the bushing 28. Since the distance ℓ₂ between the position pin 20 in its highest possible position and the upper end 28a of the bushing 28 when the bushing 28 is in contact with the bushing support 40 is designed so as to be larger than the distance ℓ₁ , the position pin 20 is assuredly prevented from being engaged in the notches 29 and 29, thus making it possible to prevent a malfuction of the selector lever shift position control means 12 assuredly. The distance ℓ₁ is provided for compensating for allowance of the bushing 28, stopper 46, etc. In the meantime, by constructing so that the position pin 20 abuts upon the vertical walls of the projections 43 and 43 when the bushing 28 is in the selector lever unlocking position, it becomes possible to guide movement of the bushing 28 into and out of the notches 29 and 29 by means of the projections 43 and 43, thus making assured the movement of the position pin relative to the notches 29 and 29. Further, by constructing so that one upstanding or vertical side 29a of each notch 29 opposite to the other vertical side where the projection 29 is located is inclined outward as shown by the dotted lines in Fig. 2, it becomes easier to move the position pin 20 out of the notches 29 and 29 since such an inclined side is effective for preventing the position pin 20 from being locked in the notches 29 and 29 when the bushing 28 is driven by the solenoid 30 while receiving in the notches 29 and 29 the position pin 20. Fig. 8 shows a variant of the foregoing embodiment. In this variant, the end 34a of the solenoid pin 34 inserted into the slot 36 of the arm 38 of the bushing 28 is bent vertically downwards to constitute a vertical portion engaged in the slot 36. The solenoid pin 34 further has a horizontal portion 34b located above the arm 38. The above described limiting means 42 is constituted by the horizontal portion 34b of the solenoid pin 34 and the arm 38 of the bushing 28. The distance ℓ₁ between the horizontal portion 34b of the solenoid pin 34 and the arm 38 and the distance ℓ₂ between the position pin 20 in its highest possible position and the upper end 28a of the bushing 28 when the bushing 28 is in contact with the bushing support 40 are designed so as to satisfy the relation of ℓ₁ ≦ ℓ₂. With this structure, the arm 38 is brought into abutment upon the horizontal portion 34b of the solenoid pin when the bushing 28 moves the distance ℓ₁ , thus making it possible to limit upward movement of the bushing 28 similarly to the previous embodiment. This embodiment makes it possible to reduce the number of constituent parts as compared with the previous embodiment. In the foregoing, it will be understood that the limiting means 42 constitute safety means for preventing erroneous operation of the position pin 20, i.e., for preventing the position pin 20 from being erroneously aligned with the notches 29 and 29, and thereby attaining an assured and reliable operation of the selector lever shift position control means 12.

Claims: An automatic transmission shift control device for a vehicle having a brake pedal, comprising: a selector lever (10) movable into a plurality of gear positions including a parking position and having a hollow cylindrical post (14) having a pair of diametrically opposed openings (22) and a knob (16) attached to the upper end of said post (14); and selector lever shift position control means (12) for controlling movement of said selector lever (10); said selector lever shift position control means (12) including a position plate (18) having a profiled opening (18a) defining said gear positions, a position pin (20) installed transversely of said post (14) in said openings for up-and-down movement and releasably engaged in said position plate (18) for positioning said selector lever (10) at one of said gear positions, a rod (24) installed in said post (14) for up-and-down movement and supporting said position pin (20) at the lower end thereof, a control button (27) mounted in said knob (16) for substantially horizontal movement and cooperative with said rod (24) to disengage said position pin from said position plate (18), a bushing (28) mounted on said post (14) for rotation but against axial movement and having at the upper end a pair of diametrically opposed notches (29) with which said position pin (20) is engaged for disengaging said position pin (20) from said position plate (18), a solenoid (30) operatively connected to said bushing (28) to rotate same selectively between a first position where said notches (29) are aligned with said position pin (20) and a second position where said notches (29) are misaligned with said position pin (20), said solenoid (30) being operative in such a way that said bushing (28) is rotated into said first position when said position pin is at said parking position and the brake pedal is fully depressed and into said second position when said position pin (20) is at said parking position and the brake pedal is free from depression, and safety means for preventing said position pin (20) from being stuck into said notches (29), when already aligned in the notches (29), and safety means for preventing said position pin (20) for being stuck into said notches (29), wherein said safety means comprising limiting means (42), wherein said bushing (28) has at the upper end thereof a pair of axial projections (43) which are arranged on one side of said respective notches (29), said selector lever shift position control means (12) further including a bushing support (40) secured to said post (14) and supporting thereon said bushing (28), and a stopper (46) installed on said post (14) in the place above said bushing (28) so that said bushing abuts at said projections (43) upon said stopper (46) when upward movement of said bushing (28) reaches a predetermined amount, said projections (43) and said stopper (46) constituting said limiting means (42), wherein the distance l₁ between each of said projections (43) and said stopper (46) is determined so as to satisfy the relation of l₁ ≦ l₂ where l₂ is the distance between said upper end (28a) of said bushing (28) and said position pin (20) in its highest possible position. An automatic transmission shift control device as set forth in claim 1 wherein one upstanding side of each of said notches (29), opposite to the other upstanding side where each of said projections (43) is located, is inclined outwards. An automatic transmission shift control device as set forth in claim 1 wherein said bushing (28) has a radially projecting arm (38) which is formed with a slot (36), and said solenoid (30) has a solenoid pin (34) engaged at an end in said slot (36). An automatic transmission shift control device for a vehicle having a brake pedal, comprising: a selector lever (10) movable into a plurality of gear positions including a parking position and having a hollow cylindrical post (14) having a pair of diametrically opposed openings (22) and a knob (16) attached to the upper end of said post (14); and selector lever shift position control means (12) for controlling movement of said selector level (10); said selector lever shift position control means (12) including a position plate (18) having a profiled opening (18a) defining said gear positions, a position pin (20) installed transversely of said post (14) in said openings for up-and-down movement and releasably engaged in said position plate (18) for positioning said selector lever (10) at one of said gear positions, a rod (24) installed in said post (14) for up-and-down movement and supporting said position pin (20) at the lower end thereof, a control button (27) mounted in said knob (16) for substantially horizontal movement and cooperative with said rod (24) to disengage said position pin from said position plate (18), a bushing (28) mounted on said post (14) for rotation but against axial movement and having at the upper end a pair of diametrically opposed notches (29) with which said position pin (20) is engaged for disengaging said position pin (20) from said position plate (18), a solenoid (30) operatively connected to said bushing (28) to rotate same selectively between a first position where said notches (29) are aligned with said position pin (20) and a second position where said notches (29) are misaligned with said position pin (20), said solenoid (30) being operative in such a way that said bushing (28) is rotated into said first position when said position pin is at said parking position and the brake pedal is fully depressed and into said second position when said position pin (20) is at said parking position and the brake pedal is free from depression, and safety means for preventing said position pin (20) from being stuck into said notches (29), when already aligned in the notches (29) and safety means for preventing said position pin (20) for being stuck into said notches (29), wherein said safety means comprising limiting means (42), wherein said bushing (28) has a radially projecting arm pin (38) which is formed with a slot (36), and said solenoid (30) has a solenoid pin (34) engaged at an end in said slot (36), wherein said end of said solenoid pin (34) is bent vertically downward to constitute a vertical portion engaged in said slot (36), said solenoid pin (34) further having a horizontal portion (34b) located above said arm (38) so that said arm (38) abuts upon said horizontal portion (34b) when upward movement of said bushing (28) reaches a predetermined value, said solenoid pin (34) and said arm (38) constituting said limiting means (42), and wherein the distance l₁ between said horizontal portion (34b) and said arm (38) is determined so as to satisfy the relation of l₁ ≦ l₂ where l₂ is the distance between said position pin (20) in its highest possible position and said upper end (28a) of said bushing (28) when said bushing is in contact with said bushing support (40).

Inventors: KATO KOJI C O WASHIZU PLANT FU, KOBAYASHI SATOSHI, YAMAZAKI HIROSHI C O OHI SEISA, KATO, KOJI C/O WASHIZU PLANT FUJI KIKO CO., LTD., KOBAYASHI, SATOSHI, YAMAZAKI, HIROSHI C/O OHI SEISAKUSHO CO., LTD.
Applicants: FUJI KIKO KK, NISSAN MOTOR, OHI SEISAKUSHO CO LTD, FUJI KIKO CO., LTD., NISSAN MOTOR CO., LTD., OHI SEISAKUSHO CO., LTD.
Application year: 1988
Main classification: F16H61
IPC codes: F16H59