WO1997038245A1

WO1997038245A1 - Hydrostatic, continuously variable force transmission device

Info

Publication number: WO1997038245A1
Application number: PCT/EP1997/001813
Authority: WO
Inventors: Georg Albersinger
Original assignee: Georg Albersinger
Priority date: 1996-04-11
Filing date: 1997-04-11
Publication date: 1997-10-16
Also published as: DE29706516U1; DE19614381A1

Abstract

In order to obtain a hydrostatic, continuously variable force transmission device with a high efficiency, a substantially smaller size and therefore a reduced weight, it is proposed that two displacement units (4, 5) be arranged in a housing. The displacement units (4, 5) are two spherical dome-shaped inner shells (4a, 5a) arranged on a common longitudinal axis (9a, 10a) in such a way that the faces of the inner shells (4a, 5a) face each other with an axial gap. A control piston unit (6) arranged between the front faces of the inner shells (4a, 5a) delimits in the axial direction two working chambers (2, 3) filled with a hydrostatic medium, together with the two inner shells (4a, 5a). The control piston assembly can rotate around the longitudinal axis (9a, 10a) and has two non-parallel faces (6c, 6d) whose angle of inclination with respect to the longitudinal axis (9a, 10a) is adjustable. Separating elements (7) which project into the two working chambers (2, 3) subdivide each working chamber (2, 3) into a pressure half (2a and 3a) and a suction half (2b and 3b). The working chambers (2, 3) are in fluid communication with each other through control openings (6e) in the control piston assembly (6). When the inner shell (4a, 5a) or control piston assembly (6) turn around the longitudinal axis (9a, 10a), a pressure difference is created in the hydrostatic medium between the pressure half (2a, 3a) and the suction half (2b, 3b) of each working chamber (2, 3). The pressure difference causes force to be transmitted from the driving part (4a or 5a; 6) to the driven part(s) (6; 4a and/or 5a), depending on the difference between a first (A1) and a second (A2) cross-sectional areas of the control piston assembly (6). The ratio (n1/n2) between the speeds of rotation of the driving part (4a or 5a; 6) and the driven part(s) (6; 4a and/or 5a) can be continuously regulated by adjusting at least one inclination angle of one face (6c, 6d) of the control piston assembly (6).

Description

HYDROSTATIC CONTINUOUSLY ADJUSTABLE POWER TRANSMISSION DEVICE

DESCRIPTION

The invention relates to a hydrostatic, continuously adjustable power transmission device according to the preamble of claim 1. Such a power transmission device is known from DE-A-3 143 645.

Known power transmission devices, such as those used for example as automatic transmissions in motor vehicle construction, as well as mechanical manual transmissions, have a number of fixed gears or gear ratios, which has the disadvantage that the output speed of the vehicle wheels can only be adapted to the drive speed of the internal combustion engine in relatively coarse steps is. Infinitely adjustable mechanical gears made of two adjustable pulleys and a steel link belt as a transmission belt have not proven themselves due to the high wear and the sluggish adjustment option in motor vehicle construction. Infinitely variable hydrostatic transmissions, such as are known for example from "VDI Nachrichten" No. 18, September 22, 1995, page 32, have so far not been able to establish themselves in practice because of their insufficient efficiency. The efficiency losses of such continuously variable hydrostatic transmissions result to a lesser extent from the internal friction of the transmission components and to a greater extent from flow losses due to the inevitable throttle control of the hydrostatic working medium. An additional reduction in efficiency results from the fact that the output of the working medium increases with increasing output speed, which results in the highest working medium throughput at maximum output. Although this effect can be reduced by combining hydrostatic transmissions with power-branching mechanical transmission stages, this increases the structural complexity and complexity of the mechanical components considerably, which results in a corresponding increase in weight, size and manufacturing costs. From DE-A-3 143 645 a continuously variable hydrostatic power transmission device is already known, which consists of the series arrangement of an adjustable hydrostatic pump and a hydrostatic motor in a rotating housing. In this known power transmission device, the flow rate of the working medium decreases to zero with increasing output speed. The size and weight of the known transmission is however unsatisfactory because of the series connection of two separate units (pump and motor) as with all other known hydrostatic stepless power transmission devices.

In contrast, the object of the invention is to provide a hydrostatic, continuously adjustable power transmission device of the type mentioned at the outset, which has a high degree of efficiency and a significantly reduced size with a correspondingly lower weight.

This object is achieved by the features in the characterizing part of patent claim 1.

Advantageous refinements and developments of the power transmission device according to the invention result from the subclaims.

The invention is based on the consideration of combining two hydrostatic displacement units not only functionally, but also in a direct structural effect. The constructive approach consists in the spherical shape as the envelope surface of both displacement units, which work according to the vane principle. A largely loss-free, stepless conversion of the power supplied in the form of a speed-torque ratio into any other speed-torque ratio with a high power density can be achieved. The high level of efficiency results from very low specific friction losses, as well as hardly any flow losses due to the direct and throttle-free transfer of the working medium between the drive units and through the same direction of rotation of drive and output. The high power density results from a large volume of the work spaces compared to the small size and from the high achievable speed level. In comparison to known automatic gearboxes, as are currently used in motor vehicle construction, the stepless power transmission device according to the invention requires only a fraction of the construction volume, weight and manufacturing costs. The stepless adjustability of the transmission ratio ensures that, for example, the driving internal combustion engine can always be operated with an optimal speed-torque ratio, which leads to a considerable reduction in fuel consumption.

The invention is explained below with reference to the exemplary embodiments shown in the drawings. It shows:

Fig. 1 is a perspective, partially cutaway view of a first

Embodiment of the power transmission device according to the invention in the form of a continuously variable transmission;

FIG. 2 shows an exploded view of the displacer and control piston units of the continuously variable transmission according to FIG. 1, which are accommodated in a spherical envelope surface, the control piston unit being adjustable via an internal mechanism;

Fig. 3 is a perspective, partially cutaway view of a

Modification of the embodiment of FIG. 1, wherein the drive-side spherical cap-shaped displacement unit is encased by a fixed support shell;

Fig. 4 is a perspective, partially cutaway view of a second

Embodiment of the power transmission device according to the invention in the form of a continuously variable transmission, which in contrast to the first embodiment according to FIGS. 1 to 3 has an adjustment mechanism for the control piston unit which extends over the outside of the displacement units;

Fig. 5 is a perspective view of a control piston unit for

Illustration of the two slot-shaped control openings between the working spaces of the hydrostatic working medium separated by the control piston unit within the spherical envelope surface;

6 to 8 are schematic views of the first embodiment of FIG. 1 with different tilt positions of the control piston unit, namely in the idle position (FIG. 6), in a middle position with the speed ratio 2: 1 (FIG. 7) and an end position with the speed ratio 1: 1 (Fig. 8);

9 shows a schematic illustration of the different cross-sectional areas typical of the control piston unit and the resulting different reaction forces, which generate the torque on the rotatable control piston unit;

Fig. 10 is a schematic development of the annular lateral surface of a

Control piston unit and the associated work spaces with their respective pressure and suction halves to illustrate the pressure differences in the work spaces and the closed flow circuit of the hydrostatic working medium between the work spaces;

Fig. 11 is a perspective, partially cutaway view of a third

Embodiment of the power transmission device according to the invention in the form of a continuously variable transmission, which in contrast to the first embodiment according to FIGS. 1 to 3 has an alternative embodiment of the separating elements and a modified internal adjustment mechanism for the control piston unit;

Fig. 12 is an axial longitudinal section through the third embodiment

11 shows the adjustment mechanism and a three-part spherical center;

Fig. 13 is a perspective, partially cutaway view of a

Modification of the third exemplary embodiment according to FIG. 11, which, like in the case of FIG. 4, has an adjustment mechanism for the control piston unit which extends over the outside of the displacement units, both displacement units being enveloped by support shells and the output being effected via the housing;

14 is a partially sectioned axial view of the embodiment of FIG. 13;

15 is a perspective, uncut representation of the variant of

Control piston unit with the two adjoining displacement units, as used in the exemplary embodiments according to FIGS. 11 to

14 are provided;

16 is a partially cutaway illustration of the assembly according to FIG.

15 with a special design of the separating elements, the control piston unit and the spherical center;

Fig. 17 is a perspective, partially cutaway view of a fourth

Embodiment of the power transmission according to the invention device in the form of a continuously variable transmission which, in contrast to the previous exemplary embodiments, has a control piston unit consisting of two control pistons arranged at an axial distance from one another;

Fig. 18 is an axial view of the fourth embodiment shown in Fig. 17;

19 is a perspective, partially cutaway view of a fifth

Embodiment of the power transmission device according to the invention in the form of a continuously variable transmission which, in contrast to the previous exemplary embodiments, has a control piston unit consisting of a two-part control piston which can be adjusted on a common pivot axis and has a doubled number of work spaces and volume cycles;

Fig. 20 is an axial view of the fifth embodiment shown in Fig. 19;

Fig. 21 is a perspective, partially cutaway view of a sixth

Embodiment of the power transmission device according to the invention in the form of a continuously adjustable, in particular usable as a differential gear, which has spring-loaded, slidably mounted separating elements with a relief groove on one side, and

22 is a partially sectioned view of a control piston unit with pressure-dependent throttling of the volume flow between the work spaces for the special use of the control piston unit in transmissions according to the invention, which are operated as differential gears. A first embodiment of a power transmission device according to the invention is shown in perspective in FIG. 1 and in an exploded view in FIG. 2. The associated start, end and middle positions are illustrated schematically in FIGS. 6, 7, 8. Furthermore, FIGS. 9 and 10 schematically show the basic principle of the power conversion as well as the flow and pressure conditions.

A housing 1 has a spherical inner surface lc, which serves as an enveloping surface for two spherical cap-shaped displacement units 4, 5, which are arranged on a common longitudinal axis 9a, 10a and with their end faces 4b, 5b (FIG. 6) lie opposite one another at an axial distance . The drive-side displacement unit 4 is rotatably mounted about the longitudinal axis 9a, 10a to the housing section la in a rotary bearing 9b, while the other displacement unit 5 is fixedly connected to the housing section 1b. The space remaining between the end faces of the displacement units 4, 5 is rotationally symmetrical with respect to the longitudinal axis 9a, 10a and is divided into two spaces by means of a control piston unit 6. The control piston unit 6 is rotatably mounted about the longitudinal axis 9a, 10a and takes the output shaft 10 with it. The control piston unit 6 is constructed around a spherical center 6f, which separates and delimits the spaces on both sides of the control piston unit 6 towards the center thereof. This results in two ring-shaped working spaces 2, 3 (FIG. 3) between the housing inner surface 1c, displacement units 4, 5 and control piston unit 6, which are filled with a hydrostatic medium. Each of the two displacement units 4, 5 consists of a spherical cap-shaped inner shell 4a, 5a, which is provided on its end faces 4b, 5b (FIG. 6) with radial slots 4c, 5c (FIG. 6) arranged in a star shape. Wing-like or slide-like separating elements 7 are received in these radial slots 4c, 5c in such a way that the separating elements can be pivoted about the center of their spherical cap-shaped inner shell 4a, 5a. The degree of freedom of this mobility is limited by the spherical inner surface 1c of the housing and the spherical center 6f of the control piston unit 6. This pivoting movement is controlled in that the separating elements 7 on the facing end face 6c, 6d of the control piston unit 6 forcibly. This compulsory system is ensured in that a driver lug 7a is integrally formed on the lower, free end of each separating element 7 and hooks into an annular guide groove 8 at the transition between the control piston unit 6 and the spherical center 6f. The two ring-shaped work spaces 2, 3 (FIG. 3) are divided into a plurality of work space cells by means of these separating elements 7. To supply the individual workspace cells with the medium, an annular groove 5d is provided on the fixed spherical cap-shaped inner shell 5a, which distributes the medium to corresponding bores 5e, which are provided with an integrated check valve 5f. The connection of the annular groove 5d to the outside is made through a hole ld in the housing section lb. The inner shell 4 on the drive side likewise has an annular groove 4d (FIG. 6) which is not visible in FIG. 1 and which corresponds to the annular groove 5d. The annular grooves 4d, 5d (FIG. 6) serve in both inner shells 4a, 5a to compensate for the changes in volume of the free spaces within the radial slots 4c, 5c (FIG. 6) behind the moving separating elements 7.

The mode of operation and the interaction of the two hydrostatic displacement units 4, 5 is determined by the design of the control piston unit 6, which is explained in detail below and which, in the transmission according to FIG. 1, functions as the output, the control of the working medium and the adjustment of the Funding takes over.

The main feature of the control piston unit 6 is its end-side annular surfaces 6c, 6d (FIG. 9) which delimit the respective working space 2, 3 and which are arranged non-parallel, ie with mutual inclination to one another. An imaginary cross-sectional plane 6g (FIG. 9) runs through the longitudinal axis 9a, 10a and cuts through the control piston unit 6 such that the part of the cross-sectional area lying above the longitudinal axis 9a, 10a (hereinafter referred to as "upper cross-sectional area A,") is maximum, and the part lying below the longitudinal axis 9a, 10a (hereinafter referred to as "lower cross-sectional area A ₂ ") is minimal. The upper and lower apex regions are the upper and lower cross-sectional areas A ₁ , A ₂ corresponding areas of the respective end-side annular surface 6c, 6d of the control piston unit 6 understood. The separating elements 7 in the apex areas - they are closest to the cross-sectional plane 6g - divide the two working spaces 2, 3 into a pressure half 2a, 3a and a suction half 2b, 3b each. The two opposite pressure halves 2a, 3a, like the two opposite suction halves 2b, 3b, are in direct fluidic connection between the upper and lower apex regions through pressure-side or suction-side, slit-shaped control openings 6e.

When the drive-side displacement unit 4 rotates, as can be seen from the development according to FIG. 10, between the pressure halves 2a, 3a (with the pressure p,) and the suction halves 2b, 3b (with the pressure pj) of each working space 2 or 3 a pressure drop, the differential pressure öp = pi - P ₂ acting perpendicular to the cross-sectional plane 6g on the entire cross-sectional area A, -fA _{2 of} the control piston unit 6. According to the different sizes of the upper and lower cross-sectional area A _u A ₂ act on their priorities different forces F ,, F _2, where in effect the difference between these two forces (ώF = F, - F ₂₎ at the focus of the larger upper cross-sectional area A, is present. Via the distance r from this center of gravity to the longitudinal axis 9a, 10a, the differential force ÖF generates a torque in a direction of rotation that is identical to the direction of rotation of the drive, with which the desired power transmission to the output shaft 10 (FIG. 2) is effected.

Another function of the control piston unit 6 is to continuously adjust the speed ratio between the drive shaft 9 and the output shaft 10. For this purpose, the control piston unit 6 is mounted such that it can be tilted about a pivot axis 6a perpendicular to the longitudinal axis 9a, 10a and perpendicular to the cross-sectional plane 6g (FIG. 9). For this purpose, in the embodiment according to FIG. 2, the disk-shaped control piston unit 6 with the cylindrical bore 6i (FIG. 9) of its spherical center 6f is mounted on a spherically shaped hub 10 of the output shaft 10, so that the cylindrical bore 6i is located on the spherical surface of the Hub lOe can roll around the swivel axis 6a. To tilt the control piston unit (6) around the In the embodiment according to FIG. 2, the pivot axis 6a is used for an actuating device guided in the hollow output shaft 10. An actuator 14c (FIG. 1) transmits a static linear movement via a rotary inlet 14 to a drive ring 14a which rotates with the output shaft 10. The driver ring 14a engages via a radial driver pin 14b (which can be axially displaced in the axial longitudinal slots 10d of the output shaft 10) in a push rod 12 which is axially displaceably mounted in the interior of the output shaft 10. In this way, the linear adjustment movement for the control piston unit 6 is transmitted from the actuator 14c into the interior of the output shaft 10.

In the embodiment according to FIG. 2, tappets 13 are moved on the push rod 12 by wedge-shaped inclined surfaces 12a which run against one another and which are mounted in a radially movable manner in the spherical center 6f. The upper ends of the plungers 13 lie against the inner bore 6i (FIG. 9) of the center 6f of the control piston unit 6 and, depending on their radial position (which depends on the axial position of the push rod 12), tilt the control piston unit 6 clockwise or counterclockwise around the pivot axis 6a. As a result, the control piston unit 6 can be continuously tilted back and forth between the end positions shown in FIGS. 6 and 8, in which one of the non-parallel end faces 6c, 6d of the control piston unit 6 is perpendicular to the longitudinal axis 9a, 10a. For example, FIG. 7 shows a central position in which the angles between the respective end face 6c, 6d and the longitudinal axis 9a, 10a are the same, the speed ratio 2: 1 being set in this position. 6 is the idle position, while in the end position according to FIG. 8 there is a transmission ratio of 1: 1. For coupling the rotary movement of the control piston unit 6 to the output shaft 10, a bore 6k coaxial to the pivot axis 6a is provided in the spherical center 6f in FIG. 9, into which a driver pin 6h (FIG. 11) is inserted. In FIG. 10 the ring-shaped surface of the control piston unit 6 and the associated working spaces 2, 3 are developed on one level to illustrate the volume flow. Here you can see the two inner shells 4a, 5a and their separating elements 7, which bear against the facing end face 6c, 6d (FIG. 9) of the control piston unit 6 shown in its central position (FIG. 7). The slit-shaped control openings 6e between the pressure halves 2a, 3a and the suction halves 2b, 3b are also shown here. The pressure and suction halves of each work space 2, 3 are subdivided from one another by those separating elements 7 which currently bear against the webs of the end faces 6c, 6d between the slot-shaped control openings 6e. As a result of this separation of the pressure halves 2a, 3a from the respective suction halves 2b, 3b, the above-mentioned pressure drop occurs within each working space 2 or 3, which is the cause of the power transmission to the control piston unit 6.

10, the rotary movement 9c initiated on the drive side is shown as a linear movement of the corresponding inner shell 4a. If the drive-side inner shell 4a is moved in the direction of the arrow 4e and the pressure half 2a of the work space 2 is viewed, the volume of the individual work space cells of the work space 2 is reduced, as a result of which the medium flows into the pressure half 3a of the opposite work space 3. In order to avoid the increasing medium volume, one would expect the inner shell 5a to move in a direction opposite to the drive-side inner shell 4a. Since the inner shell 5a is firmly connected to the stationary housing section 1b, only the rotatably mounted control piston unit 6 can evade the increasing media volume, with the result of a rotary movement of the control piston unit 6 in the same direction of rotation as the drive-side inner shell 4a. As a result of the relative movement of the control piston unit 6 to the fixed inner shell 5a, the volume of the working space cells of the working space 3 increases, as a result of which the medium can be taken up. At the same time, the medium is transported to the suction half 3b of the work space 3, where the same process takes place analogously to the pressure half 2a of the work space 2 plays, whereby here the volume flow takes place from the fixed inner shell 5a to the driven inner shell 4a. Through their relative movement with respect to the control piston unit 6, the medium is in turn conveyed in the direction of the pressure half 2a of the working space 2, so that the circuit of the medium closes.

The speed ratio n, / n ₂ is set by the corresponding setting of the tilting angle of the control piston unit 6. If one considers, for example, the pressure halves 2a, 3a, the drive-side displacement unit 4 delivers a certain volume V per revolution. Analogously, the pressure half 3a of the fixed displacement unit 5 takes up a certain volume V ₂ per revolution. The size of the delivered or absorbed volumes per revolution depend on the angle of the respective end face 6c, 6d of the control piston unit 6 with respect to the longitudinal axis 9a, 10a. Since, due to the closed circuit, the total volume V, • n conveyed by the drive-side displacement unit 4 (in relation to time) corresponds to the volume V ₂ • n _{2 received} by the fixed displacement unit 5, the ratio of the volumes conveyed per revolution has an effect V ,, V ₂ directly on the speed ratio:

n,

V, «n, = V ₂ « n ₂ = =>

V,

The variable n here means the relative speed of the drive-side displacement unit 4 with respect to the control piston unit 6, while the variable r ^ means the relative speed of the control piston unit 6 with respect to the fixed displacement unit 5. Since in this exemplary embodiment the control piston unit 6 represents the output, the actual drive speed determines

n = n, + n ₂ , the actual gear ratio

nn, + n ₂

1 =

The actual flow rate of the working medium within this cycle increases continuously from idling (flow rate 0) to the gear ratio 2: 1 (maximum flow rate) and then continuously decreases again to the gear ratio 1: 1 (flow rate 0). This means that overall relatively little medium is transported and that a hydrostatic standstill occurs at a ratio of 1: 1.

Further exemplary embodiments of the power transmission device according to the invention are described below, only their differences from the exemplary embodiment according to FIGS. 1 and 2 being explained.

The second exemplary embodiment shown in FIG. 3 improves by using a hemispherical support shell 11 which surrounds the drive-side displacement unit 4 and is connected to it in a rotationally fixed manner. This displacer unit 4 together with the support shell 11 is slidably or roller-mounted relative to the housing la, as a result of which the sliding friction between the drive-side inner shell 4a and the housing section la of the exemplary embodiment according to FIG. 1 is eliminated. Furthermore, the sealing of the working space 2 is reduced to the impact between the support shell 11 and the housing section 1b.

In the exemplary embodiment according to FIG. 4, the housing sections 1 a, 1 b are connected in a rotationally fixed manner to the control piston unit 6 and follow their rotation and pivoting movement. This design enables the use of an external adjustment mechanism for the control piston unit 6 with a bow-shaped push rod 12 and rotary lead-in 14. The push rod 12 connects the housing sections 1a, 1b to the rotary lead-in 14 in a moving manner. The output-side displacement unit 4 is non-rotatably coupled to an outer protective housing 100 by means of a hub 5g. In addition, this design enables a guide groove 8, which is incorporated in the housing sections 1 a, 1 b, for the forced guidance of the separating elements 7.

FIGS. 11 and 12 show an exemplary embodiment of a force transmission device in which, instead of individually movable separating elements 7, wing-like separating elements 7 which are rigidly arranged on a closed carrier ring 71 are used. These wing rings 71, with their smooth surface 71c facing the control piston unit 6, each slide against the respectively adjacent end surface 6c, 6d of the control piston unit 6. Between the separating elements 7, passage openings 71b (FIG. 15) for the working medium are made in the annular surface, which openings are aligned with the slot-shaped control openings 6e of the control piston unit 6. The separating elements 7 dip into radial slots of frustoconical recesses 18 of the inner shells 4a, 5a, which are dimensioned such that the separating elements 7 have a deflection in the recesses 18 (FIG. 15) of the inner shells 4a, 5a corresponding to the tilting position of the control piston unit 6 can execute. In order to ensure the compensation of this deflection and at the same time the sealing of the individual work area cells to one another, frustoconical sealing and compensating rings 18a are embedded in the recesses 18, in the radial slots of which the separating elements 7 slide in. The movement-dependent volume compensation within the sealing and compensation rings 18a takes place via channels 7b (FIG. 16) which extend within the separating elements 7 in the direction of the control piston unit 6.

The advantages of the construction according to FIG. 11 are a smaller number of individual parts to be sealed, a loss of individual control of the separating elements 7, and a more favorable, improved sliding friction behavior between the separating elements 7 and sealing and compensating rings 18a compared to the construction according to FIG. 1 11 is the embodiment of the internal adjustment in connection with a spherical center, which consists of a three-part inner ball 61, on which the control piston unit 6 is pivotably mounted. As shown in FIG. 12, the inner ball 61 comprises a central part 61c, which is connected to the output shaft 10 in a rotationally fixed manner, and two side parts 61a, 61b which are rotatably mounted on the output shaft 10 via roller bearings 61d with respect to the central part 61c. The roller-supported side parts 61a, 61b of the inner ball 61 serve for low-friction and stable support of the inner shells 4a, 5a, which enables better guidance of the inner shells 4a, 5a and improved sealing of the work clearances to the longitudinal axis 9a, 10a. The adjustment of the control piston unit 6 is carried out by means of a transmission lever 17 integrated in the middle part 61c of the inner ball 61, which is actuated by a push rod 12 axially displaceably arranged in the center of the output shaft 10 by means of a rotary introduction 14 similar to that shown in FIG. The transmission lever 17 has ball heads at its ends, which engage in an articulated manner in a blind bore 12b of the push rod 12 and in a radial bore 6m of the control piston unit 6. The spherically thickened shaft between the ball heads of the transmission lever 17 rolls on the inner surface of a radial bore in the central part 61c of the inner ball 61 and in this way transmits the pushing force of the push rod 12 acting on the lower ball head to the upper ball head and thus the control piston unit 6. The control piston unit 6 and the central part 61c of the inner ball 61 are coupled to the output shaft 10 by means of the shafts 6h of the pivot axis 6a and form an internal output.

In the exemplary embodiments according to FIGS. 13 and 14, features from FIGS. 3 and 4 are used in an expanded form. The spherical outer shell for the inner shells 4a, 5a consists of two spherical cap-shaped support shells 11 and a one- or two-part middle ring (ring sections 15a, 15b). The output takes place from the control piston unit 6 through the central ring 15a, 15b into the housing 1 by means of the adjusting shaft 14e, the entire housing 1 rotating is executed. The two support shells 11 are non-rotatably connected to the respective displacement units 4, 5, the central ring 15 forming a unit with the housing 1 and thereby allowing the adjustment shaft 14e to be introduced from the outside. An actuating bracket 14d, which is coupled to the adjusting shaft 14e, is pivoted with an actuator 14c which also rotates. These measures enable an externally attached adjustment for the control piston unit 6 with simultaneous output guidance via the housing 1.

FIGS. 15 and 16 show a variant of the power transmission device shown in FIG. 11, which differs in that an external adjustment (similar to that in FIGS. 13 and 14) including housing output and multi-part support shell 11, 15a, 15b for Application comes. By eliminating an internal adjustment mechanism and an output shaft 10, the wing ring 71 and the respective spherical cap 71a can be connected to one another in one piece. The two spherical caps 71a are mounted on the control piston unit 6 arranged therebetween in a precise and low-friction rolling or sliding manner in the radial and axial direction. The one-piece connection of wing rings 71 and spherical caps 71a further reduces the sealing surfaces for work spaces 2, 3 and, in particular, enables a hermetic seal in the center of the transmission.

In the power transmission device according to FIGS. 17 and 18, the displacement units 4, 5, in contrast to the exemplary embodiments described so far, are not combined to form a ball, but are arranged with their center points at an axial distance from one another. As a result, the inner shells 4a, 5a can be enlarged beyond the center of the hemisphere, as a result of which substantially larger swivel angles can be realized for each of the two control pistons 64, 65 of the control piston unit 6. The separate pivot axes 6a, 6b of the control pistons 64, 65 are located in the region of the facing end face 4b, 5b of the inner shells 4a, 5a, which can be enlarged up to beyond the center of the hemisphere, as a result of which the deflection of the separating elements 7 is significant if wing rings 71 are used reduced and thus their sealing simplified. Anywhere selectable axial distance between the displacement units 4, 5, more complex adjustment mechanisms can be installed, for example for an independent adjustment of the two end faces 6c, 6d of the control piston unit 6.

In the embodiment according to FIGS. 19 and 20, a design of the control piston unit, which is divided into two in the region of the pivot axis 6a, is provided. This division of the doubling of the circuit of the hydrostatic medium results. A separate work process therefore takes place in each control piston half 62, 63. The actuation of the divided control piston halves 62, 63 can be carried out in a mirrored manner, similarly to the undivided control piston unit 6 (FIG. 13). In this design, the output takes place via the central ring 15, which rests slidingly against the two support shells 11 at their joints. The right shell 11 has a shaft extension Ila, which is held in a rotationally fixed manner, as in FIGS. 19, 20 is indicated schematically by an arrow. Since the end faces of the divided control piston halves 62, 63 form only in the end positions of a plane, only wing-like separating elements 7 can be used in this embodiment in single execution and without positive control. These separating elements 7 are preferably controlled by spring elements 72 and / or hydrostatically. The separating elements 7 are provided with a groove 7c on one side, which ensures the volume compensation on the rear side in the guide slot 4c, 5c of the inner shell 4a, 5a. This type of control of the separating elements 7 by means of spring elements 72 and the hydrostatic relief of the separating elements 7 can of course also be used in all other exemplary embodiments with individual separating elements 7. The same also applies to the use of the two-part control piston unit in the exemplary embodiments according to FIGS. 1 to 16 and in the differential gear according to FIGS. 21 and 22.

FIGS. 21 and 22 show an application of the principle of a power transmission device according to the invention in the form of a continuously variable transmission as a differential transmission. All of the five exemplary embodiments described above can also be used as differential gears, for example for power distribution in vehicle drive axles are used. In the embodiment shown in FIG. 21, the control piston unit 6 serves as a drive unit, while both displacement units 4, 5 with their shaft extensions 101, 102 each form an output unit.

As an alternative to forced control, the separating elements 7 shown in FIG. 21 are pressed against the control piston unit 6 by prestressed spring elements 72, as already shown in FIGS. 19 and 20 is provided. Furthermore, in the separating elements 7, the hydrostatic relief of the rear slot space is also ensured by a groove 7c on one side.

The control piston unit 6 shown in FIG. 22 is specially equipped with a slide-type valve block 66 for use as a differential gear. The valve block 66 is used, depending on the pressure of the medium, to at least specifically close the control-side control openings 6e in order to throttle the volume flow between the working spaces 2, 3 (FIG. 10) and thereby reduce the differential effect to the full Achieve lock. In addition, an overload safety device in the form of a pressure relief valve 66a is integrated in this valve block 66 (FIG. 22), which is used during peak loads, e.g. when the vehicle starts up in a flash, a bypass between the pressure and suction sides opens. These control functions can also be carried out, for example, remotely.

There are several advantages specifically for differential gears: The O output torque can be infinitely distributed as desired by adjusting the tilt angle of the control piston unit 6 to both displacement units 4, 5. The regulation of the locking effect brings considerable advantages, especially in tough off-road or motor sport applications. The overload protection device 66a can be used above all to improve the starting behavior of vehicles.

Claims

P A T E N T A N S P R U C H E

Hydrostatic continuously variable power transmission device, with a housing (1) in which two displacement units (4, 5) are arranged, characterized in that in the housing (1) as displacement units (4, 5) two spherical cap-shaped inner shells (4a, 5a ) are arranged on a common longitudinal axis (9a, 10a) in such a way that the inner shells (4a, 5a) face each other at an axial distance with their end faces, so that a control piston unit (6) is arranged between the end faces of the inner shells (4a, 5a) Which, with the two inner shells (4a, 5a), delimits two working spaces (2, 3) filled with a hydrostatic medium in the axial direction, so that the control piston unit (6) can be rotated about the longitudinal axis (9a, 10a) and two non-parallel end faces (6c, 6d), whose angle of inclination with respect to the longitudinal axis (9a, 10a) is adjustable in each case, that separating elements (7) protrude into both working spaces (2, 3), which each work Subdivide the space (2, 3) into a pressure half (2a or 3a) and a suction half (2b or 3b) so that the working spaces (2, 3) are in fluid communication with one another via control openings (6e) in the control piston unit (6) , and that when an inner shell (4a, 5a) or the control piston unit (6) rotates about the longitudinal axis (9a, 10a) in the hydrostatic medium, a pressure drop between the pressure half (2a, 3a) and the suction half (2b, 3b) of each work space (2, 3) is generated, which is a function of the difference between a first (A,) and a second (A ₂ ) cross-sectional area of the control piston unit (6) causes the power transmission from the driving part (4a or 5a; 6) to the driven part (s) (6; 4a and / or 5a), the speed ¬ ratio (n./nj) between the driving part (4a or 5a; 6) and the driven part (s) (6; 4a and / or 5a) by adjusting at least one angle of inclination of an end face (6c, 6d) of the Control piston unit (6) is infinitely adjustable.

2. Power transmission device according to Anspmch 1, characterized in that the spherical cap-shaped inner shells (4a, 5a), the control piston unit (6) and the working spaces (2, 3) are delimited by a spherical envelope surface.

3. Power transmission device according to claim 1 or 2, characterized in that the control piston unit (6) can be tilted about a pivot axis (6a) which is oriented perpendicular to the common longitudinal axis (9a, 10a) of the displacement units (4, 5).

4. Power transmission device according to one of claims 1 to 3, characterized in that the control piston unit (6) consists of two partial pistons (62, 63; Fig. 19) which can be pivoted in opposite directions about a common tilt axis (6a). 5. Power transmission device according to Anspmch 1 or 2, characterized in that the control piston unit (6) consists of two axially spaced control pistons (64, 65; Fig. 17), which are independent of each other about separate, parallel pivot axes (6a, 6b) The tilting axes (6a, 6b) are perpendicular to the common longitudinal axis (9a, 10a) of the displacement units (4,

5) are oriented.

6. Power transmission device according to one of claims 1 to 5, characterized in that for adjusting the or the angle of inclination of the end faces (6c, 6d) of the control piston unit (6) with respect to the longitudinal axis (9a, 10a) an internal adjustment mechanism (12, 13 14, Fig. 2; 12, 17, Fig. 12) is provided.

7. Power transmission device according to Anspmch 6, characterized in that the internal adjustment mechanism (12, 13 14, Fig. 2; 12, 17, Fig. 12) has an axially displaceable push rod (12) mounted inside the output shaft (10), which are in operative connection with the pivotably mounted control piston unit (6), the axial position of the push rod (12) forming a measure of the tilting angle of the control piston unit (6).

8. Power transmission device according to Anspmch 6, characterized in that the push rod (12) is non-positively connected to one end of a transmission lever (17), the other end of which is non-positively connected to the control piston unit (6), the transmission lever (17) is supported between its ends.

9. jPower transmission device according to one of claims 1 to 5, characterized in that for adjusting the or the angle of inclination of the end faces (6c, 6d) of the control piston unit (6) with respect to the longitudinal axis (9a, 10a) an external adjustment mechanism (12, 14, 14d , 14e; FIGS. 4, 13, 19) is provided.

10. Power transmission device according to Anspmch 9, characterized in that the external adjustment mechanism (12, 14, 14d, 14e; Figs. 4, 13, 19) has at least one bow-shaped push rod (12) which is operatively connected to the control piston unit (6) .

11. Power transmission device according to Anspmch 10, characterized in that the bow-shaped push rod (12) engages via at least one actuating bracket (14d; FIGS. 13, 19) on the control piston unit (6) in its pivot axis (6a, 6b).

12. Power transmission device according to one of claims 7 to 11, characterized in that the push rod (12) can be driven via a rotary introduction (14).

13. Power transmission device according to one of claims 1 to 12, characterized in that the separating elements (7) of each working space (2, 3) in radial slots (4c, 5c) of the associated spherical cap-shaped inner shell (4a, 5a) are guided in a reversing manner.

14. Power transmission device according to Anspmch 13, characterized in that the separating elements (7) are positively controlled in such a way that they rest flush on the associated end face (6c, 6d) of the control piston unit (6).

15. Power transmission device according to Anspmch 14, characterized in that for their positive control, the separating elements (7) are operatively connected to at least one guide groove (8) provided on the end face (6c, 6d) of the control piston unit (6).

16. Power transmission device according to Claim 13 or 14, characterized in that the separating elements (7) are pressed against the associated end face (6c, 6d) of the control piston unit (6) by spring means (72) or hydrostatic means having the same effect (FIGS. 19, 21).

17. Power transmission device according to one of claims 1 to 12, characterized in that the separating elements (7) of each working space (2, 3) are rigidly attached to a wing ring (71) which is parallel to the associated end face (6c, 6d) of the control piston unit (6) is guided and engages with its separating elements (7) in recesses (18) of the associated spherical cap-shaped inner shell (4a, 5a).

18. Power transmission device according to Anspmch 17, characterized in that each wing ring (71) has passage openings (71b) which produce a passage to the control openings (6e) of the control piston unit (6).

19. Power transmission device according to Anspmch 17, characterized in that radially slotted inserts (18a) are used in the recesses (18) to compensate and to seal the separating elements (7).

20. Power transmission device according to one of claims 1 to 19, characterized in that each separating element (7) with at least one in the longitudinal direction of the separating element (7) extending groove (7c) or bore (7b) is provided which provides a fluidic connection between an assigned cell of a work space (2 or 3) and the spaces within the radial slots (4c, 5c) or the recesses (18) of the inner shell (4a, 5a) behind the separating elements (7).

21. Power transmission device according to one of claims 1 to 19, characterized in that the spaces within the radial slots (4c, 5c) or the recesses (18) of the inner shell (4a, 5a) behind the separating elements (7) separately from the work spaces (2nd , 3) are fluidly connected to one another.

22. Power transmission device according to one of claims 1 to 19, characterized in that at least one inner shell (4a, 5a) is at least partially surrounded by a Stütz¬ shell (11) which is rotatably connected to the associated inner shell (4a, 5a).

23. Power transmission device according to claim 22, characterized in that both inner shells (4a, 5a) are surrounded by support shells (11) and that the support shells (11) abut against their one-piece or multi-part middle ring (15; 15a, 15b) .

24. Power transmission device according to Anspmch 23, characterized in that the central ring (15; 15a, 15b) with the control piston unit (6) and optionally with the housing (1) is rotatably connected and serves as an output or drive.

25. Power transmission device according to one of claims 1 to 24, characterized in that each working space (2, 3) radially to the longitudinal axis (9a, 10a) are limited by a spherical boundary surface.

26. Power transmission device according to Anspmch 25, characterized in that the spherical boundary surfaces of the working spaces (2, 3) are formed by a spherical center (6f) of the control piston unit (6) (Fig. 2).

27. Power transmission device according to Anspmch 25, characterized in that the spherical boundary surfaces of the working spaces (2, 3) are formed by an inner ball (61).

28. Power transmission device according to Anspmch 27, characterized in that the inner ball (61) is constructed in three parts, the central part 61c) being connected in a rotationally fixed manner to the output and the two side parts (61a, 61b) being rotatably mounted with respect to the central part (61c).

29. Power transmission device according to Anspmch 28, characterized in that the control piston unit (6) is pivotally mounted on the central part (61c) of the inner ball (61).

30. Power transmission device according to Anspmch 29, characterized in that in the central part (61c) a radial Bohmng is provided, in which the transmission lever (17) is supported (Fig. 12).

31. Power transmission device according to Anspmch 27, characterized in that the inner ball (61) is constructed in three parts, the central part being formed by the control piston unit (6) and each side part (71a) being rotatably mounted about an axis which is perpendicular to the facing end face ( 6c, 6d) of the control piston unit (6).

32. Power transmission device according to Anspmch 31, characterized in that each side part (71a) is rigidly connected to the associated wing ring (71) (Fig. 16).

33. Power transmission device according to Anspmch 5, characterized in that the displacement units (4, 5) are arranged with their centers at an axial distance from one another (FIGS. 17, 18).

34. Power transmission device according to Anspmch 33, characterized in that the inner shells (4a, 5a) are enlarged to beyond the center of the hemisphere.

35. Power transmission device according to Anspmch 33 or 34, characterized in that the separate, mutually parallel pivot axes (6a, 6b) of the control piston (64, 65) run essentially through the center points of the assigned inner shells (4a, 5a).

36. Power transmission device according to one of claims 1 to 35, characterized in that both displacement units (4, 5) are provided as the output and the control piston unit as the drive in the sense of using the power transmission device as a differential gear.

37. Power transmission device according to Anspmch 36, characterized in that a controllable valve (66) is provided which is arranged in the flow path between the working spaces (2, 3) in order to throttle the volume flow between the working spaces (2, 3) to control.

38. Power transmission device according to Anspmch 36 or 37, characterized in that a controllable valve (66a) is arranged in a bypass between the pressure and suction half (2a, 3a; 2b, 3b) of each working space (2, 3).

39. Power transmission device according to one of claims 1 to 38, characterized in that the medium can be fed into several or all cells of at least one working space (2, 3) via bores (5e) which are in an inner shell (4a, 5a) or in the housing (1) are attached and, if necessary, provided with check valves.