GEARBOX CONTROL DEVICE FOR MOTOR VEHICLES

Abstract: A control device for a change gear for motor vehicles, comprises a single rod (16) for the selective control of the insertion of the highest gear and the reverse gear, this rod (16) being axially displaceable between a first end operative position corresponding to the insertion of the highest gear, and a second end operative position corresponding to the insertion of the reverse gear, and also having an intermedi­ ate neutral position between the two end operative posi­ tions, a fork (17) for controlling the insertion of the highest gear, fixed on said rod (16), an auxiliary element (24) for controlling the insertion of the reverse gear, mounted in a freely slidable manner on the said rod (16), one-way locking means (25, 26, 27, 28, 29, 31) which connect the auxiliary element (24) to the said rod (16), these means being designed to maintain the auxiliary element (24) in a fixed position on the said rod (16) when the latter is displaced between the neutral position and the second end operative position, and to enable, on the other hand, a free sliding of the rod (16) with respect to the auxiliary element (24) when the rod is displaced between the neutral position and the first end operative position, the said locking means also being designed to lock the auxiliary element (24) in a fixed axial position with respect to the gearbox structure when the said rod (16) is displaced between its neutral position and the first end operative position.

Description: Control device for a change gear for motor vehicles. The present invention relates to a control device for a change gear for motor vehicles. The object of the invention is to provide a device of the type mentioned above which is particularly simple and reliable and which enables a gearbox of reduced size to be achieved. The device of the invention is characterised in that it comprises - a single rod for the selective control of the insertion of the highest gear and the reverse gear, which rod may be axially displaced between a first end operative position corresponding to the insertion of the highest gear, and a second end operative position corresponding to the insertion of the reverse gear, and also has a neutral intermediate position between the said end operative positions, - a fork for controlling the insertion of the highest gear, fixed on the said rod, - an auxiliary element for the control of the insertion of the reverse gear mounted in a freely slidable manner on the said rod, - one-way locking means which connect the auxiliary element to the said rod, these means being designed to maintain the auxiliary element in a fixed position on the said rod when the latter is displaced between the neutral position and the second end operative position, and to enable, on the other hand, free sliding of the rod with respect to the auxiliary element when the rod is displaced between the neutral position and the first end operative position, the said locking means also being designed to lock the auxiliary element in a fixed position with respect to the gearbox structure when the said rod is displaced between its neutral position and the first end operative position, acco±-dan#t With a fourth¯ characteristic feature, the said one-way locking means comprise: : - a check element mounted slidably in a transverse through hole of the auxiliary element and designed to cooperate with a reference notch provided in the said rod in order to keep the auxiliary element locked on the said rod, - a contact surface on which the said check element slides, this surface being designed to maintain the check element in the engaged position within the said reference notch, - a stop surface designed to prevent forward movement of the auxiliary element from the neutral position of the rod in the direction of the first end operative position of this rod, - a seat provided in the said contact surface at the position assumed by the check element when the rod is in its neutral position, in order to enable the release of the check element from the reference notch and a simultaneous partial insertion of this check element within the said seat when the rod is displaced from the neutral position to the first end operative position, and - resilient means disposed within the said seat and tending to urge the check element against the said rod in order to cause the snap fastening of the check element in the reference notch when the rod is moved from the first end operative position to its neutral position. Further features and advantages of the invention are illustrated in the following description which is made with reference to the attached drawings, given purely by way of non-limiting example, in which: Fig. 1 is a sectional view of a device of the invention, and Fig. 2 is a sectional view along the line Il-Il of Fig. 1. In the drawings, the reference numeral 1 indicates an overall control device for a change gear for motor vehicles. The control device l is disposed within the gearbox 2. The gear construction with which the device 1 is associated is not shown in the drawings as it is of conventional type. The gearing comprises in particular a series of gear pairs which are constantly in engagement and synchronization devices for the control of the insertion of the various gears. In the example illustrated, the gearbox comprises five gears for forward movement and a gear for reverse movement. The synchroni-zation devices which control the insertion of these gears are controlled, in a manner known per se, by forks, one of which is shown at 3 in Fig. 1. The fork 3 is designed to control the insertion of the first and second gears and has a hub 3a (see also Fig. 2) fixed on a rod 4 which is slidably mounted in the gearbox 2. In accordance with conventional techniques, the rod 4 comprises an end operative position, shown by the dashed line in Fig. 2 corresponding to the insertion of the first gear, a second end operative position, shown by the dashed line II in Fig. 2, corresponding to the insertion of the second gear and a central neutral position. The rod 4 is also provided, in a manner known per se, with three reference notches 4a, 4b, 4c designed to cooperate with a spherical element or the like urged resiliently against the rod 4 in order to enable the snap locking of this rod in each of the said three positions. The hub 3a of the fork 3 which is fixed on the rod 4 is provided with a projection 5 having a notch 6 designed to receive a finger 7 projecting radially from a control shaft 8 mounted to rotate about its geometrical axis 9 in the gearbox 2. The shaft 8 is also mounted in an axially slidable manner in the gearbox 2 and is returned by springs 10 to the neutral position shown in Fig. 1. In this position, the finger 7 is taken up in the notch 11 of a lug 12 having a hub 13 fixed on a rod 14 for controlling the insertion of the third and fourth gears. On the rod 14 there is fixed a hub 15 of a fork (not shown) designed to control the synchronization device for the insertion of the third and fourth gears. In a similar manner to the rod 4, the rod 14 has two end operative positions corresponding respectively to the insertion of the third and the fourth gear and an intermediate neutral position, the said three positions being defined by the engagement of b spherical element or the like urged resiliently against the rod 14 in one of the three reference notches 14a, 14b, 14c with which the rod 14 is provided. The control device of the invention comprises a third rod 16, mounted slidably in the gearbox 2, on which rod there is fixed a sleeve 17 forming part of a fork (not shown) for controlling the insertion of the fifth gear. There is also fixed to the rod 16 a hub 18 having a lug projection 19 (see Fig. 1) whose free end has a notch 20 designed to cooperate with the finger 7. The rod 16 also has a first end operative position, shown by the dashed line V in Fig. 2, corresponding to the insertion of the fifth gear, a second end operative position, shown by the dashed line RM corresponding to the insertion of the reverse gear and an intermediate neutral position. When the three rods 4, 14, 16 are all in their neutral positions, the notches 6, 11, 7 are aligned, as a result of which it is possible to bring the finger 7 into engagement within any one of these notches by means of an axial displacement of the shaft 8. A subsequent rotation of the shaft 8 about its axis 9 leads, by means of the finger 7, to an axial displacement of the rod which is connected to this finger. The insertion of the reverse gear is obtained, in a conventional manner by means of the axial displacement of a gear 21. This axial displacement is controlledviaa rocker lever 22 mounted in an articulated manner about an axis 23 on the fixed structure of the gearbox, by an auxiliary element 24 which is mounted in a freely slidable manner on the rod 16. In the example illustrated, the auxiliary element 24 has, in particular, two end portions 24a, 24b mounted slidably on the rod 16 and connected together by a spacer wall 24c. The auxiliary element 24 is also provided with projections 24d between which the end of the rocker lever 22 which cooperates with the auxiliary element is engaged. One-way locking means are provided and keep the auxiliary element 24 locked on the rod 16 when the latter is displaced between its neutral position and the end operative position corresponding to the insertion of the reverse gear, and enable, on the other hand, the sliding of the rod 16 with respect to the auxiliary element 24 when the rod is displaced between its neutral position and the end operative position corresponding to the insertion of the fifth gear. In the example illustrated, these one-way locking means comprise a pin 25 mounted slidably in a through radial hole 26 provided in the end portion 24a of the auxiliary element 24 and designed to cooperate with a reference notch 27 provided on the surface of the rod 16. Wxn therod 16 is displaced between its neutral position (shown in Fig. 2) and the end operative position corresponding to the insertion of the reverse gear, the end of the pin 25 facing the rod 14 slides on the outer surface of this rod. In this way, the said surface of the rod 14 maintains the pin 25 in the engaged position in the reference notch 27 as a result of which the auxiliary element 24 is displaced together with the rod 16 causing the insertion and release of the reverse gear by means of the rocker lever 22. When the rod 16 is displaced from its neutral position in the direction of its end operative position corresponding to the insertion of the fifth gear, the end portion 24a of the auxiliary element 24 meets a stop surface 28 defined by the gearbox 2, as a result of which the latter prevents further displacement of the auxiliary element 24. The rod 14 has a seat 29 corresponding to the position assumed by the pin 25 when the rod 16 is in its neutral position. Within the seat 29 there is disposed a sensor element 30 urged by a spring 31 in the direction of the rod 16. When the rod 16 is urged in the direction of its end operative position corresponding to the insertion of the fifth gear, from its neutral position, this displacement is not accompanied by a corresponding displacement of the auxiliary element 24 as the latter, as mentioned above, meets the stop surface 28. The further displacement of the rod 16 causes, however, a release of the pin 25 from the reference notch 27. The pin 25 is therefore urged radially outwardly, with respect to the axis of the rod 16 and is partially taken up within the seat 29 following a retraction of the sensor element 30 and a compression of the spring 31. During this stage, the pin 25 acts as a connection element between the auxiliary element 24 and the rod 14. Since, during this stage, the rod is in a fixed axial position (as the device has, in a manner known per se, a series of pins 32 cooperating with corresponding notches provided on the rods 4, 14, 16 such that when one of the rods 4, 14, 16 is axially displaced, the others are locked in position), the auxiliary element 24 is therefore locked in a fixed position with respect to the gearbox structure. As shown in the preceding description, the control device of the invention has a single rod 16 for controlling the insertion of the reverse and the fifth gears. The insertion of the reverse gear is controlled by the auxiliary element 24 which is displaced together with the rod 16 when the latter moves between its neutral position and the end operative position corresponding to the insertion of the reverse gear, whilst it remains locked in a fixed axial position when the rod 16 is displaced between its neutral position and the end operative position corresponding to the insertion of the fifth gear. The locking of the auxiliary element on the rod with respect to a single direction of movement of the rod is obtained by means of the pin 25 which is also used for locking the auxiliary element 24 in a fixed axial position during the insertion and release of the fifth gear. Naturally, whilst the principle of the invention remains the same, the structural details may be greatly varied with respect to the details given above purely by way of example.

Claims: CLAIMS 1. A control device for a change gear for motor vehicles, comprising: - a single rod (16) for the selective control of the insertion of the highest gear and the reverse gear, this rod (16) being axially displaceable between a first end operative position corresponding to the insertion of the highest gear, and a second end operative position corresponding to the insertion of the reverse gear, and also having an intermediate neutral position between the two end operative positions, - a fork (17) for controlling the insertion of the highest gear, fixed on the said rod (16), - an auxiliary element (24) for.controlling the insertion of the reverse gear, mounted in a freely slidable manner on the said rod (16), - one-way locking means (25, 26, 27, 28, 29, 31) which connect the auxiliary element (24) to the said rod (16), these means being designed to maintain the auxiliary element (24) in a fixed position on the said rod (16) when the latter is displaced between the neutral position and the second end operative position, and to enable, on the other hand, a free sliding of the rod (16) with respect to the auxiliary element (24) when the rod is displaced between the neutral position and the first end operative position, the said locking means also being designed to lock the auxiliary element (24) in a fixed axial position with respect to the gearbox structure when the said rod (16) is displaced between its neutral position and the first end operative position. 2. A device as claimed in claim 1, characterised in that the said one-way locking means comprise: - a check element (25) mounted slidably in a transverse through hole (26) of the auxiliary element (24) and designed to cooperate with a reference notch (27) provided in the said rod (16) in order to maintain the auxiliary element (24) locked on the said rod, - a contact surface (14) on which the said check element (25) slides, designed to maintain the check element (25) in the engaged position in the said reference notch (27), - a stop surface (28) designed to prevent forward movement of the auxiliary element (24) in the direction of the first end operative position of the rod (16), from the neutral position, - a seat (29) provided in the said contact surface (14) at the position assumed by the check element (25) when the rod is in its neutral position, in order to enable the release of the check element (25) from the said reference notch (27) and a simultaneous partial insertion of this check element (25) in the said seat (29) when the rod (16) is displaced from its neutral position to the first end operative position, - resilient means disposed in the said seat (29) and tending to urge the check element against the said rod (16) in order to provide the snap engagement of this check element (25) in the reference notch (27) when the rod (16) is moved frsm its first end operative position to the neutral position. 3. A device as claimed in claim 2, in which there is provided a further rod for selectively controlling the insertion -of two further gears of the gear change, and in which there are provided means for locking this further rod in an axial position when the rod for inserting the fifth and reverse gears is displaced, characterised in that the said contact surface is defined by the surface of the said further rod (14).

Inventors: NEPOTE, LUCIANO
Applicants: FIAT AUTO S.P.A.
Application year: 1985
Main classification: G05G5
IPC codes: F16H63