REVERSE GEARING

Abstract: The invention relates to a reverse gearing, which is switchable by means of couplings, whereby the input shaft (6) and the output shaft (9) lie in line with each other. A compact reverse gearing, which is easy to assemble can be obtained by according to the invention making use of face gears which are mounted on the input (6) and output shaft (9). The cylindrical pinions (24) placed between the face gears and in mesh therewith are mounted in an intermediate ring (13). A coupling can connect the intermediate ring to the housing (1). Another coupling can connect the input (6) and the output shaft (9) to each other directly or indirectly by way of the toothing.

Description: REVERSE GEARING The invention relates to a reverse clutch, comprising an input shaft, an output shaft and an intermediate ring which are rotatable about a common axis of rotation in a housing and relative to each other, and cylindrical pinions which are in mesh with a first gearwheel mounted on the output shaft, a second gearwheel which is in mesh with the cylindrical pinions, a first coupling which can connect the rotation of the input and the output shaft to each other, and a second coupling which can couple the intermediate ring to the housing. Such reverse clutches are known, for example from US-A-5,344,370, which discloses a reverse clutch which is used in motor cars, in particular in a transmission with variable transmission ratio. In the case of such reverse clutches it is still necessary to keep the speed of rotation more or less the same when reversing the direction of rotation, which necessitates special constructions when gearwheels having different diameters are used. For this purpose, in the known device the input shaft is connected to a planet ring on which the cylindrical pinions are rotatably mounted, and the cylindrical pinions are in mesh with a second gearwheel in the form of a planetary gear, which forms part of the intermediate ring which can be connected by means of a coupling to the housing and is in mesh with a gearwheel mounted on the output shaft. The disadvantage of the known reverse clutch is that, in order to obtain the opposite direction of rotation, the cylindrical pinions always have to be designed in pairs, the cylindrical pinions being in mesh with each other, and the first cylindrical pinion of the pair being in mesh with the planetary gear, while the second cylindrical pinion is in mesh with the gearwheel mounted on the output shaft. This makes many parts necessary, and the reverse clutch is relatively expensive and complex to assemble. The object of the invention is to eliminate the abovementioned disadvantages, and to that end the second gearwheel is mounted on the input shaft, and the cylindrical pinions which are each in mesh with the first and the second gearwheel are mounted between them in the intermediate ring. This produces a compact transmission, in which the same cylindrical pinion is in mesh simultaneously with both gearwheels. The result of this is, inter alia, that the number of parts can be smaller, which also simplifies the assembly, and that there are fewer tooth meshings, which means a positive influence on the noise production. This also makes it possible, if the number of cylindrical pinions is kept the same, with the dimensions remaining the same, to transmit a higher torque, because then the number of meshings with the first and the second gearwheel doubles. According to a further improvement of the invention, the axis of rotation of the cylindrical pinion is more or less perpendicular to the common axis of rotation. A compact design of the reverse clutch which is simple to produce is achieved in this way. According to a further improvement of the reverse clutch according to the invention, in which the inter- mediate ring, and the coupling connected thereto, is movable in the axial direction relative to the housing, either the first gearwheel or the second gearwheel is slidable in the axial direction relative to the output shaft or the input shaft respectively. This makes it possible to slide the clutch into the housing in the direction of the shaft during mounting, which greatly simplifies the assembly. According to a further improvement of the invention, the distance between the first and the second gearwheel is adjustable. This means that the tooth meshing can be set beforehand, before assembly in the housing, with the result that the assembly is further simplified. According to a further improvement of the inven- tion, the first coupling comprises a slide bush mounted on the output or input shaft, the teeth of which can engage with the input or the output shaft respectively by sliding in the axial direction. This means that in the situation where the direction of rotation is not being reversed a direct coupling of the shafts is possible, and no slip can occur in the clutch. According to a further improvement of the inven- tion, the first coupling has a diameter which is greater than the first and/or the second gearwheel, and the second coupling has a diameter which is smaller than the first and/or the second gearwheel. It consequently becomes possible to make the reverse clutch shorter, which can be advantageous, for example for use in motor cars. A further improvement is achieved by the fact that the first gearwheel and the second gearwheel are mounted in such a way that they are slidable in the axial direction relative to each other. Accurate adjustment of the first gearwheel and the second gearwheel relative to the cylindrical pinions mounted between them is consequently simple. According to a preferred embodiment of the invention, the intermediate ring is centred about the axis of rotation under the influence of the tooth forces on the cylindrical pinions. This ensures that no additional bearings are needed for the intermediate ring, and that the cylindrical pinions always adjust in the best possible way relative to the first and the second gearwheel. The invention is explained below with reference to a number of exemplary embodiments which are illustrated by means of a drawing. In the drawing: Fig. 1 shows part of a section of a reverse clutch according to a first embodiment of the invention; Fig. 2 shows part of a section of a reverse clutch according to a second embodiment of the invention; Fig. 3 shows part of a section of a reverse clutch according to a third embodiment of the invention; and Fig. 4 shows part of a section of a reverse clutch according to a fourth embodiment of the invention. Corresponding parts are always indicated as far as possible by the same reference numbers in the various figures. Fig. 1 shows part of a section of a reverse clutch of the type known from US-A-5344370, from which the purpose and the use of a reverse clutch according to the exemplary embodiment can be deduced. Such reverse clutches are used, for example, as reversing devices when using a continuously variable transmission in a motor car. In this case it is necessary to be able to reverse the direction of rotation of the engine, so that the vehicle can also be reversed. Fig. 1 shows a housing 1, in which an input shaft 6 is fixed by means of bearings 4 in such a way that it rotates about an axis of rotation 7. The input shaft 6 is rotatably fixed by means of bearings 8 on an output shaft 9, which is fixed by means of bearings (not shown) in the housing 1 in such a way that it likewise rotates about the axis of rotation 7. A spline toothing 10 is provided on the input shaft 6, around which toothing a primary face gear 12 is fixed so that it is slidable in the direction of the axis of rotation 7. The primary face gear 12 is rotatably fixed by means of an intermediate bearing 15 on the output shaft 9, and a secondary face gear 17 and a coupling ring 20 are likewise fixed on the output shaft 9. The axial displacement under the influence of the tooth forces of the primary face gear 12 relative to the secondary face gear 17 is limited by a locking ring 16. A face gear toothing 11 of the primary face gear 12 is in mesh with a cylindrical pinion 24, and a face gear toothing 18 of the secondary face gear 17 likewise. The cylindrical pinion 24 is rotatably fixed by means of bearings 23 on a pinion pin 14. The pinion pin 14 is fitted in an intermediate ring' 13, so that the rotation of the intermediate ring 13 can be connected by means of a coupling 22 to the rotation of the coupling ring 20, and thus to the output shaft 9, and the rotation of the intermediate ring 13 relative to the housing 1 can be stopped by means of a coupling 25. Three or more cylindrical pinions are accommodated in the intermediate ring 13, so that the intermediate ring 13 is centred relative to the axis of rotation 7 by means of the toothings 11 and 18. A pressure ring 21 can slide in the axial direction under the influence of oil supply through an oil channel 19, after which the plates of the coupling 22 are pressed in a known manner against each other, and as a result of which the rotation of the intermediate ring 13 is connected to the rotation of the output shaft 9. The rotation of the input shaft 6 and that of the output shaft 9 are now connected to each other by way of the face gear 17 , the cylindrical pinions 24 and the face gear 12. If the direction of rotation has to be reversed, the coupling 22 is released by removing the oil pressure in channel 19, after which a spring (not specified any further) pushes back the pressure ring 21 against the coupling ring 20. A pressure ring 2 is then pressed in a manner comparable to that described above against the plates of the coupling 25, with the result that the intermediate ring 13 comes to a standstill in the housing. The direction of rotation of the primary face gear 12 is now opposite to that of the secondary face gear 17 , with the result that the input shaft 6 and the output shaft 9 also rotate in opposite directions. In order to permit assembly of the reverse clutch in the direction of the shaft in an undivided housing, the various parts should be mounted so that they are slidable in the direction of the shaft. First of all, the input shaft 6 and the pressure ring 2 are mounted in the housing 1. Inter alia, the intermediate ring 13 with couplings 22 and 25, and the primary face gear 12 and the secondary face gear 17, which are positioned and adjusted relative to each other, are mounted on the output shaft 9. This assembly is then slid into the housing 1, which is possible through the fact that the various bearings are in the form of roller bearings and the fact that the plates of the coupling 25 can slide into the housing. In order to provide the various toothings, bearings and coupling plates with sufficient oil, an oil channel 3 is fitted, oil channels likewise being provided at various other points to ensure an adequate oil supply. An oil seal 5 is fitted between the housing 1 and the input shaft 6. Various other design details are also shown in the drawing, which details are a matter of course for a technical draughtsman, and will therefore not be elaborated any further here. Fig. 2 shows an exemplary embodiment which is comparable to the embodiment of Fig. 1, in which the primary face gear 12 and the secondary face gear 17 are more easily adjustable relative to each other, owing to the fact that the distance between the face gears can be adjusted by means of an adjusting nut 27 mounted on the input shaft 6, the secondary face gear 17 being held in position by a thrust bearing 26 placed between the face gear 17 and the adjusting nut 27. The face gears and the couplings are assembled and adjusted on the input shaft 6 and mounted in the housing 1, after which the output shaft 9 is mounted in a manner not shown. The rotation of the output shaft 9 is brought about by coupling with the secondary face gear 17 by way of the spline toothing 10. Fig. 3 shows an embodiment in which the distance between the primary face gear 12 and the secondary face gear 17 is set to a maximum value with the adjusting nut 27, and in which the minimum distance between the face gears is determined by a sliding ring 28. This ensures that there is always a slight tooth play between the toothings. Fig. 4 shows an embodiment in which in the situation where the direction of rotation of the input shaft 6 and the output shaft 9 (not shown) is the same the toothings of the face gears 12 and 17 are not placed under load, owing to the fact that the input shaft 6 is coupled directly to the secondary face gear 17. To this end, a slide bush 30, which rotates with the input shaft 6 by means of the spline toothing 31, is fitted around the input shaft 6. The slide bush 30 can be pushed in the direction of the secondary face gear 17 by a pressure ring 29, as a result of which a coupling toothing 32 meshes. The pressure ring 29 acts in a known manner on oil pressure, and when the oil pressure is removed the coupling toothing 32 is uncoupled through the fact that the slide bush 30 slides away, partly under the influence of a spring of the secondary face gear. The coupling toothing 32 can take a high torque and can consequently have a relatively small diameter. This makes it possible to fit the one coupling inside the face gear toothing and the other coupling outside it. A shorter fitting length can be achieved as a result, which can be a great advantage particularly for use in motor cars. It is also possible to use a synchronization ring (not shown) in the case of the coupling toothing 32, by means of which ring the speed of rotation of the coupling halves to be coupled is synchronized, so that they slide into each other without jolting. A coupling comparable to the slide bush 30 and coupling toothing 32 can, of course, also be used in the case of the coupling 25, so that there too a smaller diameter may be selected if desired, with the result that the reverse clutch can be made more compact. In the situation where one or both couplings 22 and 25 are in the form of a switch toothing with a slide bush, a coupling toothing and possibly a synchronization ring, a coupling is preferably placed between the input shaft and the engine. If the reverse clutch is being used for driving a motor car, said coupling can be in the form of, for example, a hydraulic coupling or a torque converter. The invention can be varied in various ways, for example by not making the number of teeth of the primary and the secondary face gear exactly the same, so that, for example, vibrations can be reduced. It is also possible for the axis of rotation of the cylindrical pinions not to be at right angles to the axis of rotation 7 of the input and/or output shaft, which makes the face gears easier to produce with a hobbing cutter. It is then in fact possible to avoid cutting through the shaft with the cutter.

Claims: Claims 1. Reverse clutch, comprising an input shaft (6) , an output shaft (9) and an intermediate ring (13) which are rotatable about a common axis of rotation (7) in a housing (1) and relative to each other, and cylindrical pinions (24) which are in mesh with a first gearwheel (17) mounted on the output shaft, a second gearwheel (12) which is in mesh with the cylindrical pinions, a first coupling (22; 30, 32) which can connect the input and the output shaft to each other, and a second coupling (25) which can couple the intermediate ring to the housing, characterized in that the second gearwheel is mounted on the input shaft, and the cylindrical pinions are in mesh with the first and the second gearwheel and are mounted between them in the intermediate ring. 2. Reverse clutch according to claim 1, characterized in that the axis of rotation (14) of the cylindrical pinion is more or less perpendicular to the common axis of rotation. 3. Reverse clutch according to claim 1 or 2 , in which the intermediate ring, and the coupling connected thereto, is slidable in the axial direction relative to the housing, characterized in that either the first gearwheel or the second gearwheel is slidable in the axial direction relative to the output shaft or the input shaft respectively. 4. Reverse clutch according to claim 1, 2 or 3, characterized in that the distance between the first and the second gearwheel is adjustable. 5. Reverse clutch according to one of claims 1 - 4, characterized in that the first coupling comprises a slide bush (30) mounted on the output or input shaft, the teeth (32) of which can mesh with the input or the output shaft respectively by sliding in the axial direction. 6. Reverse clutch according to one of claims 1 - 5, characterized in that the first coupling has a diameter which is greater than the first and/or the second gearwheel, and the second coupling has a diameter which is smaller than the first and/or the second gearwheel. 7. Reverse clutch according to one of the preceding claims, characterized in that the first gearwheel and the second gearwheel are mounted in such a way that they are slidable in the axial direction relative to each other. 8. Reverse clutch according to claim 7, characterized in that the intermediate ring is centred about the axis of rotation under the influence of the tooth forces on the cylindrical pinions.

Inventors: LUYCKX JOHAN LOUIS, LUYCKX, JOHAN, LOUIS
Applicants: CROWN GEAR HOLDING B V, LUYCKX JOHAN LOUIS, CROWN GEAR HOLDING B.V., LUYCKX, JOHAN, LOUIS
Application year: 1997
Main classification: F16H3
IPC codes: F16D13, F16D25, F16H3