EP0227761A1

EP0227761A1 - Overlapping steering gear system for track-laying vehicles

Info

Publication number: EP0227761A1
Application number: EP19860904123
Authority: EP
Inventors: Hans-Jürgen EICKHOFF
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1985-06-15
Filing date: 1986-06-04
Publication date: 1987-07-08
Also published as: DE3619055A1; DE3619055C2; WO1986007324A1

Abstract

Un système à mécanisme de direction à recouvrement à rayon triple (1 plus 2) où se trouvent un mécanisme partiel hydrostatique (1) et un mécanisme partiel mécanique (2). Un arbre zéro (21) commande, par l'intermédiaire d'un mécanisme de totalisation (3) et des arbres de sortie (34), les roues à chenilles d'un véhicule à chenilles afin d'effectuer une trajectoire courbe. Pour ce système, dans la gamme du premier rayon (RI) seul le mécanisme partiel hydrostatique (1) fonctionne, dans la gamme du deuxième rayon (RII) les mécanismes partiels hydrostatique (1) et mécanique (2) fonctionnent, et dans un troisième rayon fixe (RF) seuls les mécanismes partiels mécaniques (2) fonctionnent, de sorte que la vitesse de rotation de l'arbre zéro (21) assure, dans la gamme du premier et du deuxième rayon (RI et RII), une action de direction progressive, et dans la gamme du troisième rayon, une action de direction avec un faible rayon fixe (RF). Le mécanisme partiel mécanique (2) est un système de mécanisme planétaire doté de trois ensembles de roues simples (23, 24 et 25), qui, de préférence, possèdent les mêmes roues solaires et les mêmes roues à denture intérieure.A triple spoke overlap steering system (1 plus 2) where there is a partial hydrostatic mechanism (1) and a partial mechanical mechanism (2). A zero shaft (21) controls, via a summing mechanism (3) and output shafts (34), the track wheels of a tracked vehicle to perform a curved path. For this system, in the range of the first radius (RI) only the partial hydrostatic mechanism (1) works, in the range of the second radius (RII) the partial hydrostatic (1) and mechanical (2) mechanisms work, and in a third fixed radius (RF) only the partial mechanical mechanisms (2) operate, so that the speed of rotation of the zero shaft (21) ensures, in the range of the first and second radius (RI and RII), an action of progressive direction, and in the third ray range, a steering action with a small fixed radius (RF). The mechanical partial mechanism (2) is a planetary mechanism system with three sets of single wheels (23, 24 and 25), which preferably have the same sun wheels and the same internal gear wheels.

Description

Upper bearing steering gear for caterpillars

This invention relates to a superimposed steering gear for caterpillars according to the preamble of claim 1.

Steering gearboxes of this type have proven themselves because the two drive sprockets are additionally and counter-driven in a simple manner via summation gearboxes when cornering. If the main drive, which is guided to the two planetary gears via the gearshift gearbox, is shut down, there is no parallel drive of the chain wheels, this same but opposite drive from the steering gear causes the caterpillar to rotate about the vertical axis. But even when the propulsion via the main drive acts at the same time, such superimposed steering gears arranged in this way lead to a high maneuverability of the tracked vehicle.

From DE-PS 14 80 725 a hydrostatic / mechanical or hydrodynamic steering gear is known in which, in a first embodiment, the hydrostatic and hydrodynamic and in a second embodiment the hydrostatic and mechanical steering gear in terms of power in a first embodiment in all occurring curve radii the zero wave work. Steering is stepless across the entire range. This is favorable for the operation of the steering of the tracked vehicle, especially on the road, where sensitive steering is important because the contact of the road with the chain has little slip and where the necessary steering movements are recognized in good time.

In contrast, such a steering acts too slowly in the terrain, especially when it is necessary to change quickly in the direction of travel and with small steering radii, because in the entire range from the steering radius r = infinite (straight-ahead driving) to the desired steering radius, the entire area must be traversed, which is inevitable leads to a delay. Is further due to the effect of the hydrostatic steering gear over the entire steering range and a high steering power in the small radii, the efficiency is unsatisfactory.

Furthermore, a hydrostatic / mechanical steering gear is known from DE-PS 11 74 182, in which the mechanical drive drives the zero shaft in the case of a selected smaller curve radius and the hydrostatic transmission in the case of a larger curve radius. The mechanical steering gear responds very quickly to all steering movements and also works with a high degree of efficiency, so that a high degree of mobility is possible with economical driving in the field. However, the transition from the hydrostatic to the mechanical steering area is not entirely unproblematic and therefore requires practice for the driver.

It is therefore an object of the invention to further develop a superimposed steering gear for caterpillars according to the preamble of claim 1, in particular to adapt the superimposed steering gear even better to the practical requirements and to improve the efficiency and the steerability with respect to sensitive steering without significant steering delay to improve.

This object is achieved in the same way with the characterizing features of claims 1 and 2.

Due to the three-wheel steering gear and the division into a purely hydrostatic radius range, a range with power summation, from the adjustable hydrostatic drive and the direct and in principle constant drive from the motor via the mechanical steering gear as well as a purely mechanical drive with a fixed curve radius an optimal adaptation to the practical requirements while minimizing the power losses.

In the first radius area there is a clear assignment between the steering lever deflection and the theoretical curve radius. Because the steering radius area expands according to the gear jump tighter curve radii can also be driven with a lower gear, so that this first radius range is particularly suitable for road travel. The efficiency of the hydrostatic unit is getting better and better with speeds that increase in accordance with the steering deflection, and since the steering power required is low with large steering radii, the absolute power losses are also low.

In the second hydrostatic / mechanical radius range, relatively tight curves (e.g. 24 m radius in 4th gear) can still be driven on the road, and there are also off-road areas with radii between 87 and 24 m in 4th Gear a favorable maneuverability with relatively good efficiency due to the steering power summation from the mechanical and hydrostatic partial transmissions.

Due to the mechanical superimposition in the third small radius area, optimum maneuverability with the best possible efficiency is achieved, particularly when driving off-road. The control allows the small radius to be switched on very quickly without a slower adjustment of the hydrostatic pumps hindering this process.

The claims 2 to 4 further develop the invention in an advantageous manner.

The swiveling of the control pump in the hydrostatic partial transmission from a maximum swivel angle through the zero point to the opposite maximum swivel angle enables a hydrostatic / mechanical radius range which is relatively large, so that in connection with the gears a very large number of steering requirements can be covered.

The same sun and ring gears of the simple planetary sets from the mechanical sub-transmission simplify the manufacture very much. Further details of the invention are explained on the basis of exemplary embodiments and drawings, the details of the drawing being the subject of the invention.

Show it:

1 shows a schematic representation of the overall transmission of a caterpillar vehicle

Fig. 2, the superimposed steering gear with drive

3 shows a table of the engaged clutches and brakes in the radius areas when cornering

Fig. 4 is a diagram of the swivel angle of the control pump in connection with the radius areas.

1 schematically shows an arrangement of the superimposed steering gear with the hydrostatic 1 and mechanical 2 partial transmissions, the mechanical partial transmission 2 being axially parallel to the main drive axis 45. To the left and right of the summation gears 3 there are still the side gears (not shown) with the drive chain wheels. A hydrodynamic torque converter 43 and the gearshift transmission 44 with the retarder 47 are located coaxially to the main drive axis 45. The drive of the hydrostatic sub-transmission 1 and takes place via a drive assembly 41 which is connected to the motor 4 of the tracked vehicle a branching gear 42 on which, in addition to the hydrodynamic torque converter 43 and the mechanical sub-gear 2, other consumers not shown, such as. B. fans and supply pumps are connected.

The main drive takes place from the engine 4 via the drive assembly 41 to the hydrodynamic torque converter 43 and from there via a hollow shaft 46 to the gear shift transmission 44. Via the main drive shaft 45, the two summation gears 3 z. B. driven via the ring gear 31, the retarder 47, ie between the gearbox 44 and the summation gears 3, being arranged on the main drive shaft 45.

The mechanical sub-transmission 2 is driven purely mechanically, depending on the engine speed, via the branching gear 42 and once via the hydrostatic sub-transmission 1, the pivoting angle of a control pump 11 being adjusted as a function of a steering and control unit, which is not shown.

The steering drive from the mechanical sub-transmission 2 of the superposition steering gear takes place via the zero shaft 21 on the z. B. sun gears 32 of the summation gear 3, the required opposite drive direction being generated via intermediate gears 22. In the two summing gears 3, the main drive guided via the ring gear 31 is superimposed with the steering drive which is the same on both sides, runs in opposite directions on the inside of the bend and rotates in the same direction on the outside of the bend, so that when cornering, the two output shafts 34 connected to the planet carrier 33 of the summing gear 3 are connected, have different speeds - on the one hand drive speed plus speed from the superimposed steering gear, and on the other hand drive speed minus speed from the superimposed steering gear.

In the schematic representation of the superimposed steering gear according to FIG. 2, the control valve 11 driven by the motor 4 and the oil motor 12 are arranged in the hydrostatic partial transmission 1 in a known manner. The mechanical sub-transmission 2 consists of three simple planetary gear sets 23, 24, 25 as well as the clutches A and B and the brake C for switching the superimposed steering gear 1 plus 2 and the right-hand drive clutch D and the left-hand steering clutch E, for connection to the neutral shaft 21 , depending on the desired direction of travel z. B. - D closed = right turn; E closed = left curve -. There are also two freewheels F, G and a direction of rotation Reverse gear 26 arranged, the following driving connections exist:

The zero shaft 21 with the left-hand drive clutch E and via a reversing gear 26 with the right-hand drive clutch D, an inner hollow shaft 27 on the one hand with the right-hand drive clutch D and a first freewheel F and on the other hand with the left-hand drive clutch E and the clutch B for the fixed Radius RF,

A hollow shaft 28 with the first F and the second freewheel G and with the planet carrier 241 of the second 24 and the sun gear 250 of the third simple planetary gear set 25,

The second freewheel G with the clutch A and the clutch B with the planet carrier 251 of the third planetary gear set 25,

The drive gear 29A for the controllable drive coming from the hydrostatic transmission 1 with the clutch A and the ring gear 232 of the first planetary gear set 23, the drive gear 29B for the motor speed-dependent, in principle constant drive with the sun gear 240 of the second planetary gear set 24 and with the Ring gear 252 from the third simple planetary gear set 25,

The sun gear 230 of the first 23 with the ring gear 242 of the second 24 simple planetary gear set 23 and the planet carrier 231 of the first simple planetary gear set 23 with the brake C,

The table in FIG. 3 indicates with an X the clutches A, B, brakes C, directional clutches D, E and the effective freewheels as they are in the radius ranges RI, RII and the fixed radius RF at one Right curve, a left curve and when driving straight ahead are effective.

In the diagram according to FIG. 4, the achievable radii are plotted over the swivel angle f of the control pump 11 of the hydrostatic sub-transmission 1. RI is the first purely hydrostatically achievable radius range and RII is the hydro- called static / mechanical radius range. RF is the small fixed radius.

From the straight line - r = infinite; Swivel angle = 0 - with increasing positive swivel angle in the direction plus according to curve rl and from w-plus maximally to> minus maximally corresponding to curve r2a and r2b, increasingly smaller radii result in the area of the partial curves rl, that is between infinity and e.g. B. a radius of 89 m can be achieved continuously and purely hydrostatically, and this radius depends on the gear selected and z. B. should correspond to the highest, fourth gear. The two subcurves r2a and r2b correspond to the hydrostatic / mechanical radius range, r2a resulting from the maximum swivel angle plus to 0 and the subcurve r2b from 0 to maximum minus as the control pump swivels. The sub-curve r2a reduces the radius from 89 to 38 m and the sub-curve r2b from 38 to 24 m. In this example, the fixed radius r3 is reached with about 15 m in the fourth gear, which corresponds to a curve radius in the first gear of about 3.3 m.

The ratio jump from the smallest hydrostatically / mechanically achievable curve radius of 24 m to the fixed radius is i = 1.58 and is completely irrelevant, especially when driving off-road. It is also possible, by means of suitable measures in the mechanical sub-transmission 2, to design this step change, and thus also the small fixed radius and the other radius ranges, depending on the task.

The three-wheel superimposed steering gear works as follows: When driving straight ahead, the right-hand steering clutch D and the left-hand steering clutch E are closed. The zero shaft 21 is thus blocked, and the drive torque which is applied to the summation gear 3 on the ring gear 31 is supported on the sun gear 32. Only the main drive coming from the manual transmission thus acts on the output shafts 34 and thus via the side gear on the chain wheels. When initiating z. B. a right turn, clutch E is released and clutch A is closed. This applies to a small steering deflection on the steering and control unit 5. Up to a theoretical curve radius of z. B. 89 m, as shown in Fig. 4, the steering overlap purely hydrostatically in the area RI corresponding to the curve rl. The speed generated by the oil motor 12, which is between 0 and plus / minus z. B. 580 rpm, supplied via the drive gear 29A to the mechanical sub-transmission and transmitted via the clutch A and the freewheels G and F and the clutch D as well as the reversing gear 26 and the zero shaft 21 to the sun gears 31 of the summation gear 3 , wherein the same, but opposite steering drive to both summation gear is achieved via an intermediate wheel 22.

In the case of a left-hand curve in which the clutch E is closed and D is open, the drive takes place via the freewheels G and F and the inner hollow shaft 27 onto the clutch E and thus onto the zero shaft 21, the direction of rotation of the zero shaft being reversed. The entire required steering power is therefore applied via the hydrostatic transmission.

In the event of a larger steering deflection corresponding to the radius area RII from FIG. 4, the drive from the hydrostatic transmission 1 is superimposed by the drive, which is dependent on the throttle lever but is otherwise constant, via the input gear 29B, since the brake C is closed and the planetary gear sets 23, 24 of the mechanical sub-transmission come into effect. The possible drive in this area from the hydrostatic transmission of z. B. plus z. B. 580 to minus 580 rpm is passed via the drive gear 29A and the planetary gear set 23 to the ring gear 242 of the planetary gear set 24. The constant drive from the motor 4 is via the drive gear 29B to the sun gear 240.

Part of the steering power thus flows from the drive gear 29A via the first planetary gear set 23 to the ring gear 242 of the second planetary gear set 24, and a second part flows from the drive gear 29B to the sun gear 240 of the second planetary gear set 24. Both partial powers are summed in the planetary gear set 24. The size of the two partial powers can be influenced by the design of the planetary gear sets.

The output takes place via the planet carrier 241 and the freewheel F, depending on the steering deflection, with a right turn via the clutch D and the reversing gear 26 to the zero shaft and with a left turn from the freewheel F via the hollow shaft 27 and the clutch E also to the Zero wave.

4, the maximum speed of the oil motor in the minus range is superimposed by the constant drive via the gearwheel 2B. Since clutch B is now also closed, there is a force profile from gear 29B via simple planetary gear set 25 and via planet carrier 251 to clutch B and via inner hollow shaft 27, as already described, via the right-hand and left-hand drive clutch D and E on the zero wave 21st

1

10

Reference list

1 hydrostatic transmission

11 control pump

12 oil engine

2 mechanical partial transmissions

21 zero wave

22 idler gears

23 first simple planetary gear set

230 sun gear

231 footbridge

232 ring gear

24 second simple planetary gear set

240 sun gear

241 footbridge

242 ring gear

25 third simple planetary gear set

250 sun gear

251 footbridge

252 ring gear 6 rotation reversing gear 7 inner hollow shaft 8 hollow shaft 9A drive gear 9B drive gear summation gear 1 ring gear 2 sun gear 3 planetary gears (land) 4 output shafts motor 1 drive assembly 2 branching gear 3 torque converter 4 gear shift 5 main drive shaft 6 hollow shaft 47 retarders

5 steering and control unit

A first clutch

B second clutch

C brake

D Right-hand drive clutch

E Left-hand drive clutch

F first freewheel

G second freewheel

RI first radius range

RII second radius area

RF fixed radius rl possible radii depending on the swivel angle in the first radius area r2a and possible radii depending on the swivel angle r2b in the second radius area f swivel angle of the control pump

Claims

Expectations

1. superimposed steering gear for caterpillar vehicles, the zero shaft (21) of which acts on the drive sprockets via summation gear (3), with a hydrostatic (1) and / / depending on the steering deflection in a control and steering unit (5) for driving the zero shaft (21) or a mechanical (2) partial transmission is used and cornering deviates from the straight line, characterized in that a three-wheel steering transmission (1 plus 2) consisting of a mechanical (2) and hydrostatic (1) partial transmission is designed such that the Straight ahead seen in a first radius area (RI) only the hydrostatic partial transmission (1) in a second radius area (RII) the hydrostatic (1) and mechanical (2) partial transmission together and in a small fixed radius (RF) only the mechanical partial transmission ( 2) change the speed of the zero shaft (21), so that in the first and second radius ranges (RI and RII) stepless steering and in a third steering with a small fixed steering radius (RF).

2. superimposed steering gear for caterpillar vehicles, the zero shaft (21) of which acts on the drive sprockets via summation gear (3), with a hydrostatic (1) and / / depending on the steering deflection in a control and steering unit (5) for driving the zero shaft (21) or mechanical (2) sub-transmission, and a cornering deviating from the straight line acts, characterized in that a three-wheel steering transmission (1 plus 2) consisting of a mechanical (2) and hydrostatic (1) sub-transmission is designed so that the mechanical Partial transmission (2) as a planetary coupling transmission with three simple planetary gear sets (23, 24, 25), two clutches (A, B), a brake (C) and two freewheels (F, G) and for coupling to the zero shaft (21 ) each has a right and left steering clutch (D, E) with the drive connections: the zero shaft (21) with the left-hand drive clutch (E) and via a reversing gear (26) with the right-hand drive clutch (D), an inner hollow shaft (27) on one side with the right-hand drive clutch (D) and a first freewheel (F) , and on the other hand with the left-hand drive clutch (E) and the clutch (B) for the fixed radius (RF), a hollow shaft (28) with the first (F) and the second freewheel (G) and with the planet carrier (241 ) of the second (24) and the sun gear (25) of the third simple "planetary gear set (25), the second freewheel (G) with the clutch (A) and the clutch (B) with the planet carrier (251) of the third tarpaulin ¬ gear set (25), the drive gear (29A) for the variable drive coming from the hydrostatic partial transmission (1) with the clutch (A) and the ring gear (232) of the first planetary gear set (23), the drive gear (29B) for the motor speed-dependent, in principle constant drive with the sun gear (240) of the second position anetenradset (24) and with the ring gear (252) from the third simple planetary gear set (25), the sun gear (230) of the first (23) with the ring gear (242) of the second (24) simple planetary gear set and the planet carrier (231) of the first simple planetary gear set (23) with the brake (C).

3. superimposed steering gear for caterpillar vehicles according to one of claims 1 or 2, characterized in that the control pump (11) of the hydrostatic Teilge¬ transmission (1) in a first radius range (RI) from 0 to the maximum swivel angle to plus (max. plus) is pivoted into a second radius range (RII) from maximum plus over 0 to an opposite pivot angle (max. minus) and is fixed in a small fixed radius (RF) in the maximum pivot range (t ^ max. minus) .

4. Superimposed steering mechanism according to claim 3, characterized in that the sun gears (230, 240, 250) and the H _* ohlräder (232, 242, 252) of the planetary gear sets (23,

24, 25) each have the same number of teeth.