DE2331980A1 - PLANETARY DIFFERENTIAL GEAR - Google Patents

Description

The invention relates to a planetary differential gear, in particular for use in connection with a vehicle when positioned either between the two driven axles of a four-wheel drive vehicle or between the two drive wheels of the same axle of a conventional drive vehicle.

In some planetary differential gears it is required that the gears of the transmission, especially those in mesh standing planet gears and the ring gear, so cooperate with each other that a viscous fluid against one Resistance is displaced, the meshing gears thus act as a pump, whereby between each other cooperating gears torque is transmitted. This torque transmission is used to influence the relative rotation exploited between the cooperating gears. An application example for such a differential gear is given in a four-wheel drive vehicle in which the differential gear is used to influence the speed difference between the front and rear wheels of the vehicle at least contributes.

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The invention is based on the object of a planetary differential gear to create in which the size of the torque transmitted between the gears can be changed is.

This object is achieved with a planetary differential gear, which according to the invention is characterized in that in a housing filled with plud a ring gear, a sun gear, with these meshing planet gears and one that carries them Web are housed, the gears are included so that they act as a gear pump in relative rotation that the Plud pumped by the gears can be received by lines that a variable opening is connected to the lines through which the pumped plud flows, and that the size of the opening is variable with a device.

A planetary differential gear of the construction described above is used in a four-wheel drive vehicle for influencing the speed difference between the front and rear wheels of the vehicle can be used.

In such a planetary differential gear, the size of the opening as a function of the speed difference be made automatically changeable between the gears. This can expediently be achieved in that the The size of the opening is made variable according to the pressure of the fluid pumped by the gears, this pressure in turn depends on the speed difference between the gears.

The web carrying the planetary gears, the sun gear and the ring gear represent the drive and output elements of the Transmission.

There can be two groups of lines in the transmission, each group being assigned a variable opening,

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and the lines and openings are formed so that upon relative rotation between the output elements of the transmission the Plud in one direction of rotation through one group of lines and the associated changeable opening and in Relative rotation in the other direction is pumped through the other group of lines and through the opening associated with them will.

A modified embodiment of the transmission is that there are two groups of lines that each Group is assigned a check valve, and that the changeable Opening is connected to both groups of lines, with relative rotation between the Abtrxebselementen of the gearbox the flow in one direction of rotation through one group of lines and from these through the changeable one Opening and with relative rotation in the other direction through the other group of lines and from these through the changeable Orifice is pumped.

In a further development of the invention it is provided that the web has an annular part encompassing the sun gear, in which a plurality of chambers are formed at an intermediate distance in the circumferential direction, facing the inner and outer circumference of the annular part are open, that a planetary gear is received in each chamber, and that the inner surfaces the Kammarn are cylindrical and only one of the outermost ends of the gear teeth in the radial direction have a small distance, the teeth of the planetary gears the recesses of the chambers to the inner and outer circumference of the penetrate ring-shaped part.

.of the bridge
Two lines can open into each chamber /, one of which belongs to one group of lines and the other to the other group of lines.

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The or each variable opening provided in the differential gear can be part of a pressure-controlled valve. That Valve can have a pressure-actuatable component that is used in increasing pressure of the fluid pumped by the gears reduces the size of the opening.

The pressure actuatable component of the or each valve can be a Be a spring-loaded piston which, in cooperation with a valve seat, forms the variable opening. The piston can urged by the spring away from the valve seat and designed so that it is displaceable against the valve seat to in Depending on the increasing pressure in the fluid pumped by the gears, the fluid flow through the valve seat increases decrease or interrupt.

The differential gear can also be provided with a combined expansion and storage chamber, with which in the Housing a certain minimum pressure of the fluid can be maintained.

If the differential gear works as a pump for a longer period of time, the temperature of the gear unit increases considerably Dimensions. The size of the variable opening can therefore be dependent on the pressure in a modification of the embodiment described above variable opening depending on the temperature of the differential gear or that of the gears pumped fluids can be made changeable.

A planetary differential gear of the embodiment described above is in particular in a vehicle with a drive motor acting on two wheels or on two groups of wheels usable in such a way that it is arranged between the drive wheels or between the drive wheel groups to the to influence existing speed difference between these.

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The invention is described below with reference to schematic drawings an exemplary embodiment explained with further details. In the drawing shows:

Pig. 1 shows a longitudinal section along the line G-C in FIG by a planetary differential gear according to the invention and by one connected to this Transfer case,

Pig. 2 shows a cross section along the line A-A in FIG. 1,

Pig. 3 shows a section along the line B-B in Pig. 2 through a! part of the transmission,

Pig. 4 is a simplified representation of a four-wheel drive vehicle with a planetary differential gear according to the invention and

Pig. Figure 5 is a graph of the typical relationship between the fluid pressure generated in the differential gear and the speed difference between the front and rear wheels of a four-wheel drive vehicle.

A planetary differential gear connecting the drive axles for arrangement between the front and rear wheels of a four-wheel drive vehicle has a Outer housing 10 on which a drive shaft 11 and two Output shafts 12 and 13 are supported.

The output shaft 12 is received in the interior of the outer housing in a bearing arrangement 16 and connected to the front wheels of the The vehicle can be connected via a sprocket wheel 14 which is held on the output shaft with a spline connection 15. The drive shaft 11 is inside the output shaft 12 in stored in a bearing 17. With the output shaft 12 is on one Weld 19 a fluid-tight two-part housing 18

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welded, which is received at the other end in a bearing arrangement which is supported on the outer housing. With output shaft connectable to the "rear wheels of the vehicle is in the interior of the housing 18 in the axial direction with spacing arranged bearing assemblies 21 and 22 stored. To seal the housing 18 against the output shaft 13 are Sealing members 23 and 24 are arranged between the two elements.

Axially directed forces acting on the output shaft 13 which tend to move the shaft according to FIG. 1 to move left, are from the output shaft to the bearing assembly 20 via a thrust bearing 30 and a pressed part transferred to the output shaft 13 in a range between a speedometer drive sprocket 26 and a backlash limiting disc 27 is attached. The transmission of these axially directed forces takes place from the bearing arrangement 20 via the housing 18 and the sprocket 14 to the other bearing arrangement 16, which is so mounted in the interior of the outer housing is that it can produce an opposing force against these forces. Axially directed forces that the aspiration have to move the output shaft 13 to the right as shown in FIG. 1, the output shaft via a further Transfer thrust bearing assembly 28 to housing 18. The bearing arrangement 16, which is shown in FIG their location inside the outer housing is held by a retaining ring.

A sun gear 31 is formed on the output shaft 12 driving the front wheels, while the rear wheels are formed with it driving output shaft 13 is connected to a ring gear 32 via projections 33 formed on its outer surface, which engage in corresponding recesses 34 on a bell-shaped formed in one piece with the output shaft 13 Part 35 are present. On the drive shaft 11 is a planetary gear carrier (web) 36 with a splined profile 37 held, which carries three planetary gears 38 received on pivot pins 39, which with the sun gear 31 and the ring gear 32

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comb. The web 36 is formed in two parts and has a main part 40 and an annular end plate 41, which is connected to the main part with circumferentially spaced screws 42 (FIG. 2). the End plate 41 and part of the main part 40 form an annular part of the web which engages around the sun gear. In the part of the main part 40, which engages around the sun gear, three chambers 43 are formed in the circumferential direction with an intermediate distance, which are open to the inner and outer circumference of the web. A planet gear 38 is received in each chamber. the Inner surfaces of the chambers are cylindrical and have the outer ends of the gear teeth in the radial direction only a short distance. The teeth of the planet gears penetrate through the recesses formed in the chambers through to the inner and outer circumference of the web in order to be able to intervene in the sun gear and the ring gear.

Two lines open into each chamber, namely at the corresponding Pig. 2 on the left side of the can a line 44, on the right Chamber side a line 45. The lines opening on the left side of the chambers are formed in the main part of the web and closed at one end by ball bearings 54, while at their other ends they are close to the inner circumference of the web are connected to a ring line 46, which is of a closure sleeve 47 and a groove 48 in the main part of the web is limited. The lines opening on the right side of each chamber are formed in the face plate 41 and on one End closed with ball bearings 55, while their other ends close to the inner circumference of the end plate 41 a further ring line 49 are connected, which of a further closing sleeve 50 and a groove 51 in the End plate is limited. The lines 44 and the ring line 46 assigned to them thus form a first group of Lines, lines 45 and the associated ring line 49 form a second group of lines.

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Like in Pig. 3 to be recognized is with the first group of Lines connected to a pressure-controlled valve 52 via a bore 53 which opens at one end into the ring line 46 and is closed with a ball bearing 56 at the other end. The pressure-controlled valve has a stepped bore 57 in which is screwed in a distributor block 58, the inlet opening 59 of which is connected to a bore 53. In the Bore 57 is also a pressure actuated element in The shape of a spring-loaded piston 60 is added, which with a shoulder 61 acting as a valve seat in the bore 57 cooperates and forms a variable opening with this. The piston has on its outer circumference grooves 62 which form a fluid flow path between the piston and the walls of the bore 57. The piston is on the manifold 58 urged to by a compression spring 63 which is received in the bore 57. There is a plurality on the manifold formed by projections 64 which provide a continuous flow path between the manifold block and the piston is guaranteed. When passing through the variable opening, the plud exits the valve via a bore 64 * formed in the end plate 41.

A pressure controlled valve is provided so that at increasing pressure of the fluid flowing through the valve, the piston 60 is displaced toward the valve seat 61, thus reducing the Reduce the size of the changeable opening. As soon as the pressure of the ITud flowing through the valve becomes sufficient reaches a high level, the piston 60 can come to rest on the valve seat 61 and thus the plud flow through the Completely interrupt the valve.

The second group of lines is via one of the shown A second pressure-controlled valve 65, which is similar to that in Pig. is designed similarly and serves to control the fluid flow through these lines in a similar manner to

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previously described to control. The distribution block of the second group of lines associated with pressure-controlled The valve is received in or near the end plate 41 and the fluid occurs when leaving the valve via a bore in the main part of the bridge.

As already mentioned, the housing 18 is made fluid-tight and filled with flud. The sealing of the housing is completed by a further set of die members 66 and 67 arranged between the web and the output shaft 12. In order to prevent the formation of air pockets inside the housing, the Flud is equipped with a combined expansion and Storage chamber 68, which is in communication with the housing interior, kept under pressure. The expansion and storage chamber 68 is of an L-shaped cross-sectional view Piston 69 and a shoulder 70 formed on the housing. The piston 69 »which engages with a seal on the housing, is urged resiliently towards the shoulder by a plate spring 71. That inside the expansion and pantry 68 piud and therefore also the flud within of the housing is thus pressurized by the plate spring 71. This helps to prevent the formation of cavities in the Flud. Another advantage of the piston arrangement described above is that the piston as a result of it Displaceability away from the shoulder 70 against the action of the plate spring 71, the thermal expansion of the in the housing can absorb located fludes.

In order to ensure the free fluid connection in the interior of the housing 18, there are on the outer circumference of the end plate 41 and of the main part 40 of the web, three flats 72 arranged at an intermediate distance in the circumferential direction are incorporated. The parts of the face plate 41 and the main part 40 of the web located between the planet gears 38 continue to have two bores 73 extending in the axial direction (FIG. 1) and two radially connected with these aligned bores 74.

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As already described, the drive force is transmitted to the front wheels of the vehicle via the sprocket 14, which is connected to the output shaft via a splined profile. A transfer case is used for power transmission 75, which is enclosed by a housing 76 screwed to the differential gear housing 10. The transfer case has another sprocket 77 attached to a shaft which is supported in housing 76 in bearing assemblies and 80 is supported. The sprockets 14 and 77 are connected to one another via two chains 81 and 82. The wave is connected to the drive axle of the front wheels with a flange.

From the above description it can be seen that when a speed difference occurs between the front and the Rear wheels of the vehicle also result in a relative rotation between the sun gear and the ring gear. This leads to a Relative rotation of the planet gears 38 in the chambers 43 and to Pumping of flud through either the first or the second group of lines and their associated pressure-controlled Valves.

In Fig. 4 is a simplified representation of the installation of the differential gear shown in Fig. 1 to 3 and transfer case shown in a four wheel drive vehicle. In this application example, the four-wheel drive Vehicle on a drive motor 100, which via a clutch 102 and a gear IO3, the differential gear transfer case assembly 101 drives in the form of training described above. The transmission of the drive on Rear wheels 104 and 105 of the vehicle take place via a drive shaft 106 and one arranged between the wheels Differential gear 107. Front wheels 108 and 109 of the vehicle are sent from the transfer case via a drive shaft 110 and a differential gear arranged between the wheels 111 driven. It makes sense that they are among the

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Drive shaft 106 leading to the rear wheels of the vehicle with the output shaft 13 shown in FIG. 1 and the drive shaft 110 for the front wheels of the vehicle is connected to the shaft 78 shown in FIG. 1.

Under normal conditions the front and rear wheels of the vehicle rotate at essentially the same speed, so that little or no relative movement occurs between the gears of the differential gear. Surrendered however, there is a considerable speed difference between the front and rear wheels because a set of wheels is spinning or locking is, this leads to relative rotation between the sun gear and the ring gear of the differential gear.

The differential gear is designed so that when driving forward of the vehicle a higher speed of the rear wheels than the front wheels rotation of the planet gears 38 accordingly Fig. 2 causes clockwise. This rotation of the planet gears is what is in the housing 18 Flud into the first group of Le .. remaining 44 and from these over the ring line 46 is pumped to the pressure-controlled valve 52. As already described, an increase in the pressure of the fluid being pumped leads to a reduction in the size of the fluid from the piston 60 and the variable opening formed on the valve seat 61. This increases the resistance against which the plate gears 38 when pumping of the fluid work, enlarged, so that the relative rotation of the differential gear parts is counteracted. this leads to also to the fact that part of the previously on the vehicle's rear wheels transmitted torque is transmitted to the front wheels of the vehicle.

The situation is similar when the vehicle is reversing the rear wheels should rotate at a higher speed than the vehicle's front wheels. The planet gears 38 run in Counterclockwise, thereby pumping fluid through the second group of lines and the associated pressure-controlled

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Valve 65. This acts in a similar manner to that previously described in connection with valve 52. Hence becomes a certain proportion of the torque previously transmitted to the vehicle's rear wheels to the front wheels of the vehicle diverted.

Due to the presence of two groups of lines with associated pressure-controlled valves, the Differential gear also spins the front wheels when the vehicle is moving forwards or backwards dominate. The likelihood that the front wheels will spin, i.e. rotate at a higher speed than the rear wheels, is much lower than in four-wheel drive vehicles normally a larger proportion of the total torque delivered by the drive motor is transmitted to the rear wheels will. If the front wheels spin when the vehicle is moving forward, the planet gears rotate counterclockwise, see above that fluid is pumped through the second group of lines and the associated pressure-controlled valve 65. Occurs this In the opposite state, when the vehicle is reversing, the planetary gears Flud pump through the first group of lines 44 and the pressure-controlled valve 52 associated therewith.

Is the speed difference between the front and rear wheels of the vehicle sufficiently large, for example when the vehicle is stands with its rear wheels in a ditch, and attempts have been made for a long time to get the vehicle out of the Driving out the trench can raise the pressure of the fluid pumped inside the housing 18 to a sufficiently high level increase so that the variable opening is completely closed. This leads to a direct drive connection between the front and rear wheels of the vehicle.

In a modification of the embodiment shown in Fig. 1 to 3 can be a single pressure-controlled with both line groups

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Be connected to the valve. In this pail is in every leadership group a check valve is provided, the fluid flow through allows the lines only in one direction, so that when the planetary gears 38 rotate clockwise, Plud through a group of lines and the pressure-controlled valve, with rotation of the planet gears in the opposite direction by the other Group of lines and .the pressure-controlled valve is pumped.

The characteristics of the pressure-controlled valve described above can be changed in many ways. Pig. 5 shows a typical pressure-speed difference diagram in which the speed difference N between the front and rear wheels of the vehicle, the pressure P generated in the differential gear is plotted. Since the pressure P is between the front and is proportional to the torque T transmitted to the rear wheels of the vehicle, the diagram in Pig. 5 also as The diagram of the transmitted torque T as a function of the speed difference N must be considered. The point A at the Curve 91 is the switch-off point at which the variable opening is completely closed.

By axially moving the distributor block 58 in the bore 57, the initial size of the piston 60 and set the variable opening formed on the valve seat 61. For example, if you partially screw the distribution block out of the bore 57, the initial size of the variable opening is increased. This results in a flatter rise of the initial curve section OA, in that the switch-off point A is shifted to the right into position A .. so that the modified characteristic curve 92 is obtained.

The spring force applied to the piston 60 by the compression spring 63 can be changed if a screw 90 with a central bore 94 is inserted into the bore 57, the axial position relative to the bore 57 the spring force

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determined (Pig. 3) · If, for example, the spring force is increased by screwing the screw 90 further into the bore 57, there is an increase in the pressure required to close the variable opening. The point A in Pig. 5 is shifted in the vertical direction to A ₂ and the modified characteristic curve 93 is obtained.

The rise in the remaining sections of curves 91, 92 and 93, that is, sections AB, A ₁ B .. and ApB ₂ , is largely dependent on the design of piston 60. If the piston is designed in such a way that, as previously described, it is able to completely interrupt the flow of fluid through the valve, then the curve sections AB, A ₁ B ₁ and A ₂ B _{2 run} almost perpendicularly. The piston can, however, be provided with a central recess or recesses or other devices which allow a controlled passage of fluid on the valve seat 61 even when the piston is in contact with the valve seat. If a controlled passage of Flud is possible, the slope of the curve sections AB, A ₁ B ₁ and A ₂ B _{2 is} less steep because it is proportional to the passage.

Although in the embodiments described above, the size of the variable opening depending on the speed difference between the front and rear wheels of the vehicle by sensing the pressure of the planetary gears pumped Fludes is changeable, it is clear that the relative rotation of the differential gear parts to a leads to increased temperature of a differential gear and the pumped fluid. It is therefore possible to use the above Replace pressure control with a temperature-dependent control if necessary, the size of the variable opening being variable by a temperature-controlled element which detects either the temperature of the differential gear or the temperature of the fluid being pumped. Here, the differential gear is protected against damage due to overheating, since the temperature-controlled element is so

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can be designed that it completely closes the variable opening before the temperature of the differential gear or of the pumped fluid reaches a level at which it would cause failure.

The invention thus creates a planetary differential gear between two groups of driving wheels in a four-wheel drive Vehicle or between vehicle driving wheels of the same axle can be arranged and that is able to Spin of the wheels before the spinning wheel group or the spinning wheel supplied torque to / for to redirect the slower turning group of wheels / wheel.

/Expectations

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Claims (14)

Expectations 1 · 1 planetary differential gear, especially for four-wheel drives, in which a ring gear, a sun gear, planet gears meshing with these and a web carrying the planet gears are arranged in a housing filled with fluid, the gears being enclosed in such a way that they are as Gear pumps act, characterized in that lines (44, 45) are provided to receive the fluid pumped by the gears (32, 31, 38) and are connected to an opening which can be changed with an adjusting device (60, 61). 2. Planetary differential gear according to claim 1, characterized in that the size of the opening in Depending on the speed difference between the gears (32,31,38) can be changed automatically. 3 · Planetary differential gear according to claim 2, characterized in that the adjusting device (60,61) can be controlled by the pressure of the fluid pumped by the gears (32,31,38). 4. Planetary differential gear according to one of claims 1 to 3, characterized in that the web (36), the sun gear (31) and the ring gear (32) represent the drive and output elements of the gear. / 2 309886/0817 43 259 5. Planetary differential gear according to claim 4, characterized in that it rejects two groups of lines (44.46; 45.49) are present that each group (44.46 and 45,49) is assigned a variable opening, and that the lines and the openings are designed so that at Relative rotation between the output elements (31,32) of the gearbox that! Plud in one direction of rotation through one Group of lines (44,46) and the associated changeable opening and through helative rotation in the other direction the other group of lines (45, 49) and is pumped through the opening assigned to them. 6. planetary differential gear according to claim 4, characterized marked that fcwo groups of lines (44,46; 45,49) are present, dap each group (44,46 resp. 45, 49) is assigned a check valve, and that the variable opening with both groups of lines (44, 46 and 45,49) is connected, with relative rotation between the output elements (31,32) of the transmission the Plud in the a direction of rotation through one group of lines (44, 46) and from these through the variable opening and with relative rotation in the other direction through the other group of lines (45, 49) and from these through the changeable one Orifice is pumped. 7. Planetary differential gear according to one of the claims 1 to 6, characterized in that the web (36) an annular part (40, 41) encompassing the sun gear (31) has, in which with Zwisohen Distance in the circumferential direction a plurality of chambers (43) is formed, which towards the inner and outer circumference of the annular part (40, 41) are open, that a planet gear (38) is received in each chamber (43), and that the inner surfaces of the chambers (43) are cylindrical and only a small distance from the outer ends of the gear teeth in the radial direction have, the teeth of the planet gears (38) the recesses 309Ö86 / ^0817/3 43 259 of the chambers (43) to the inner and outer circumference of the annular Partly penetrate (40,41). 8. Planetary differential gear according to claim 7 »in conjunction with claim 5 or 6, characterized g e k e η η ζ e i without t that two lines (44, 45) open into each chamber (43), one of which leads to the one (44, 46) and the other to the belongs to another group of lines (45 »49). 9. Plaraten differential gear according to one of the claims 1 to 8, characterized in that the or each variable opening is part of a pressure-controlled Valve (52,65), and that the or each valve (52,65) has a pressure-actuatable component (60) which at increasing pressure of the pumped by the gears (31 »3338) Fludea reduced the size of the opening. 10. "Planetary differential gear according to claim 9» thereby characterized in that the pressure-actuable component (60) in the or in each valve (52,65) is a spring-loaded Is piston which in cooperation with a valve seat (61) forms the variable opening, and that the piston (60) of the spring (63) is pushed away from the valve seat (61) and is formed in this way is that it is displaceable against the valve seat (61) in order to depend on the increasing pressure in the Gears (31 »32,38) pumped Plud through the Plud flow to reduce or interrupt the valve seat (61). 11. Planetary differential gear according to one of the claims 1 to 10, characterized in that a combined expansion and storage chamber in the housing (18) (68) is designed, with which a certain minimum pressure of the Pludes can be maintained in the housing (18). / 4 309886/0817 - -K- 43 259 12. Planetary differential gear according to claim ti, characterized Ine t denote that the combined expansion and storage chamber (68) by the interaction of a spring-loaded Piston (69) with the housing (18) is preserved and one filled with fluid and connected to the inside of the housing (18) communicating chamber forms, wherein the force of the spring (71) acts on the piston (69) that the chamber volume is minimized to thereby keep the fluid contained in the chamber (68) under pressure. 13. Planetary differential gear according to claim 1 or 2, characterized in that the size of the opening automatically depending on the temperature of the differential gear is changeable, and that the device for changing the size of the opening is a temperature-controlled component is that, as the temperature of the differential gear increases, the size of the opening is reduced. 14. Planetary differential gear according to one of claims 1 to 13, in particular »for a vehicle with one on two Wheels or drive motor driving on two groups of wheels, in particular for a vehicle with four-wheel drive, thereby characterized in that the planetary differential gear between the drive wheels or between the drive wheel groups is arranged to influence the speed difference existing between them. 309886/0817 Empty soap