DE102007035291B4 - Device for the hydraulic or pneumatic actuation of a switching element - Google Patents

Abstract

Device for the hydraulic or pneumatic actuation of a shift element (2), in particular a shift fork, in a change gear transmission, with at least one piston-cylinder system (3) which has at least one piston (4) which, while forming at least two pressure chambers (5, 6) is surrounded by at least one cylinder (7), the at least one cylinder (7) being arranged axially movably on a shift rod (8) and being in operative connection with a shift element (2), the piston (4) on or on the switching rod (8) is fixed and wherein pressure fluid inside the switching rod (8) can be conducted along at least two flow paths (9, 10) into the at least two pressure chambers (5, 6), the two flow paths (9, 10) run parallel along an axial extension (11) in the shift rod (8), characterized in that the shift rod (8) is designed at least in sections as a tube, the two flow paths (9, 10) through a into the Switching rod (8) inserted separating element (15) are formed.

Description

Field of invention

The invention relates to a device for the hydraulic or pneumatic actuation of a shift element, in particular a shift fork, in a change gear transmission, with at least one piston-cylinder system which has at least one piston which is surrounded by at least one cylinder to form at least two pressure chambers, with the at least one cylinder is axially movably arranged on a shift rod and is in operative connection with a shift element, the piston being fixedly arranged on or on the shift rod and wherein pressure fluid inside the shift rod can be conducted along at least two flow paths into the at least two pressure chambers, wherein the two flow paths run parallel along an axial extension in the shift rod.

Background of the invention

To actuate sliding sleeves in change gear transmissions, it is known to use hydraulically actuated actuators. For example, the SU 1 333 878 A1 a device for the hydraulic movement of a sliding sleeve, wherein a shift fork is arranged on a piston-cylinder system. Hydraulic oil is applied to the piston-cylinder system so that the shift fork can be moved in a desired manner.

DE 34 10 802 C2 discloses a shifting device for change gears with a shift rod carrying a shift fork which can be pushed back and forth by means of a manual shift lever engaging a driver on the shift rod with the assistance of a pressure fluid. The pressure fluid is guided in the axial direction in bores in the shift rod.

A similar solution, in which a fluid (liquid or gas) is used to actuate a switching device of a change gear transmission, is also in the DE 698 24 116 T2 described.

In U.S. 2,508,564 A air is preferably used as the fluid in order to bring about a corresponding movement; a pneumatic solution is therefore preferred here.

DD 61 173 A1 describes a compressed air-operated reversing gear for transmissions of rail vehicles. A generic device goes out EP 0 150 583 A2 emerged.

Today, especially many automated manual transmissions are equipped with such hydraulic or pneumatic actuators in order to control the shifting elements, i. H. especially the shift forks to operate. The actuators are often arranged on a transmission wall. However, this has disadvantages insofar as a not inconsiderable installation space is required for this. This is doubled if the actuator only acts on one side.

In order to reduce the installation space required in the transmission wall, the actuator - as the above-mentioned prior art shows - can be moved to the shift fork. There, too, the actuator must be supplied with pressure fluid (hydraulic oil or compressed air). As is also known in the cited prior art, the pressure fluid can be supplied through the switching rod, with the previously known solutions only being available in one pressure space in the rod.

In order to be able to execute two opposite directions of actuation of a shift fork, two pressure lines must be attached. In order to generate at least two pressure lines in the switching rod, a structural, pressure-tight separation must be made in the switching rod. Even if a separating element (e.g. a plug) is introduced into the shift rod, pressure fluid supply on both sides is still necessary, which means increased effort in the transmission.

Object of the invention

The present invention is therefore based on the object of developing a device of the type mentioned at the outset in such a way that it is possible, in a simplified manner, to conduct two different pressurized fluid flows to a piston-cylinder system with which a switching element can be actuated. Above all, it should be possible to supply the system with pressurized fluid in a particularly simple and space-saving manner.

Summary of the invention

The object is achieved by a device with all the features of claim 1. The device according to the invention is characterized in that the two flow paths run parallel along an axial extension in the shift rod.

This axial extension is not insignificant with a view to the entire length of the shift rod, but can preferably be at least 25% of the length of the shift rod.

The inflows and outflows for pressure fluid can be arranged essentially at the same axial position of the shift rod. The inflows and outflows for pressure fluid can particularly preferably be in be arranged in an axial end region of the shift rod.

The switching rod is designed at least in sections as a tube, the two flow paths being formed by a separating element inserted into the switching rod. The separating element is preferably designed as a tube which is inserted coaxially into the shift rod. This creates two pressure-tight flow cross-sections. In general, however, any other cross-sections are also possible.

The separating element can furthermore have two axially spaced locking elements at one axial end, each of which is tightly connected to the shift rod on its inner surface, the separating element having at least one fluid opening between the two locking elements.

The one locking element is preferably arranged axially at the level of the piston. The locking elements are also preferably designed as cylindrical bodies which have at least one sealing element on their outer circumference that rests against the inner surface of the shift rod.

The shift rod can have at least one passage for pressure fluid axially on both sides of the piston.

The separating element inserted into the shift rod and designed as a tube can furthermore be held and sealed in the axial end region of the shift rod by a terminating piece with an enlarged diameter and resting on the inner circumference of the shift rod.

The locking elements and / or the terminating piece are also preferably designed in one piece with the separating element. In this case, the component consisting of the separating element, locking elements and end piece can be designed as a unit that can be pushed into the tubular switching rod.

With the proposed configuration of a device for hydraulically or pneumatically actuating a shift fork in a change gear transmission, it is possible to separate two fluid flows in a simple manner and to enable pressure fluid to be supplied from one side of the shift rod. It is also possible to use two switching elements, each of which supplies one side with pressure fluid.

This allows a separate supply of the two pressure fluids to the piston-cylinder system, d. H. to the location of the actuator, which is made possible by the inlet inserted into the tubular shift rod.

The only one-sided supply of both pressure fluids enables a simple construction of the hydraulic or pneumatic supply.

The supply lines are pressure-tight, which has a positive effect on the hydraulic or pneumatic efficiency.

In this way, a pipe can be constructed fluidically separated over a relatively large length without having to resort to partition walls which can hardly be kept tight over a greater length and which are very susceptible to pressure loading.

Figure list

• An exemplary embodiment of the invention is shown in the drawing. The single figure shows schematically the section through a device for actuating a switching element in a gear change transmission.

Detailed description of the figures

In the figure is a device 1 to operate a switching element 2 shown in the form of a shift fork. The shift fork 2 engages, which is not shown, in an annular groove of a sliding sleeve in order to move it axially and thus trigger a gear change.

The axial displacement (in the figure in the horizontal direction) of the sliding sleeve takes place in the present case hydraulically, ie with a piston-cylinder system 3 that is an axial movement of the shift fork 2 relative to a shift rod 8th caused.

For this purpose, the tubular shift rod carries 8th a piston 4th of the piston-cylinder system 3 . The piston 4th is from a cylinder 7th surrounded on which the shift fork 2 is preferably set. Generally speaking, the shift fork is in place 2 with the cylinder in a suitable operative connection, ie shift fork 2 and cylinder 7th are coupled with each other.

The cylinder 7th can move in the axial direction on the shift rod 8th move. Between the piston 4th and the cylinder 7th become two different pressure rooms 5 and 6th Are defined. Becomes the right pressure chamber 5 when hydraulic oil is applied, its volume increases, so that the shift fork 2 - with a stationary switch rod 8th - is moved to the right. It is correspondingly the other way around when the other pressure chamber 6th is charged with hydraulic oil.

It is essential that the pressure fluid is inside the shift rod 8th along two flow paths 9 and 10 in the two pressure rooms 5 , 6th can be directed. According to the invention, this is done in such a way that the two flow paths 9 and 10 along a certain, in terms of the length of the shift rod 8th not inconsiderable axial extension 11th in the shift rod 8th run parallel or coaxial.

In the embodiment according to the figure, this is implemented so that in the tubular shift rod 8th a tubular separator 15th is used.

This runs along the axial extension 11th concentric to the shift rod 8th so that the two flow paths 9 , 10 train as annular spaces.

At an axial position 14th the shift rod 8th , namely at one (right) end there are two inflows and outflows 12th and 13th , into which pressure fluid - as illustrated by the arrows - can alternatively be entered.

• Hier befinden sich in axialem Abstand zwei Sperrelemente 17 und 18, die als radiale Erweiterungen des rohrförmigen Trennelements 15 ausgestaltet sind. Die Sperrelemente 17, 18 liegen mit ihrem zylindrischen Außenumfang an der inneren Wand der Schaltstange 8 dichtend an, wozu Dichtelemente 20 zwischen den Sperrelementen 17, 18 und der Schaltstange 8 vorgesehen sind. Das in der Figur rechte Sperrelement 17 ist dabei in axialer Höhe des Kolbens 4 angeordnet. Das linke Sperrelement 18 liegt in axialem Abstand links daneben. Es verhindert eine Leckage von Druckfluid in den sich weiter nach links erstreckenden Innenraum der Schaltstange 8.

Im from the inflows and outflows 12th , 13th distant other axial end 16 of the separating element 15th the following design is planned:

• Here there are two locking elements at an axial distance 17th and 18th that act as radial extensions of the tubular separating element 15th are designed. The locking elements 17th , 18th lie with their cylindrical outer circumference on the inner wall of the shift rod 8th sealing, including sealing elements 20th between the locking elements 17th , 18th and the shift rod 8th are provided. The locking element on the right in the figure 17th is at the axial height of the piston 4th arranged. The left locking element 18th lies to the left at an axial distance. It prevents leakage of pressure fluid into the interior of the shift rod, which extends further to the left 8th .

With a suitable, local choice of material for the inlet, a separate sealing element can optionally also be dispensed with. Here comes z. B. a vulcanized sealing element or a partially elastomer-like plastic in question.

Immediately axially next to the piston 4th are flows 21 and 22nd into the shift rod 8th introduced, which are designed as holes.

In the axial area between the two locking elements 17th , 18th there is at least one fluid opening 19th in the separator 15th .

This means that pressurized fluid can flow through the inflow and outflow 12th along the flow path 9 to the flow 21 and through it into the pressure room 5 flow to the shift fork 2 move to the right. Correspondingly, pressurized fluid can alternatively also be used via the inflow and outflow 13th along the flow path 10 through the fluid port 19th in the space between the two locking elements 17th and 18th and on through the flow 22nd in the printing room 6th flow to movement of the shift fork 2 to the left to accomplish. The respective flow of the pressure fluid is indicated by the arrows.

The mechanical fixing of the separating element 15th in the shift rod 8th at the right end of the same takes place by means of a terminating piece 23 that is the tubular separator 15th holds concentrically.

Over a defined axial extent 11th the shift rod 8th a structurally and hydraulically tight separation of two pressure flows is achieved.

To the double-acting piston unit with two pressure chambers 5 , 6th so lead at least two inflows and outflows 12th , 13th . Every inflow and outflow 12th , 13th the filling (active pressure side), the other correspondingly as a ventilation line (exhaust) of the other pressure chamber and vice versa. By the inlet 12th If the fluid is pumped into the pressure chamber, the vent line enables the fluid to be emptied or pushed out of the other, inactive pressure chamber. Each of the inflows and outflows 12th , 13th can therefore be an inflow and outflow line.

List of reference symbols

1

Device for actuating a switching element

2

Shift element (shift fork)

3

Piston-cylinder system

4th

Pistons

5

Printing room

6th

Printing room

7th

cylinder

8th

Shift rod

9

Flow path

10

Flow path

11th

axial extension of the shift rod

12th

Inflow and outflow

13th

Inflow and outflow

14th

axial position

15th

Separator

16

axial end of the separating element

17th

Locking element

18th

Locking element

19th

Fluid opening

20th

Sealing element

21

Flow

22nd

Flow

23

End piece

Claims (11)

Device for the hydraulic or pneumatic actuation of a shift element (2), in particular a shift fork, in a change gear transmission, with at least one piston-cylinder system (3) which has at least one piston (4) which, while forming at least two pressure chambers (5, 6) is surrounded by at least one cylinder (7), the at least one cylinder (7) being arranged axially movably on a shift rod (8) and being in operative connection with a shift element (2), the piston (4) on or on the switching rod (8) is fixed and wherein pressure fluid inside the switching rod (8) can be conducted along at least two flow paths (9, 10) into the at least two pressure chambers (5, 6), the two flow paths (9, 10) run parallel along an axial extension (11) in the shift rod (8), characterized in that the shift rod (8) is designed at least in sections as a tube, the two flow paths (9, 10) through a into the Switching rod (8) inserted separating element (15) are formed. Device according to Claim 1 , characterized in that the inflows and outflows (12, 13) for pressure fluid are arranged at the same axial position (14) of the shift rod (8). Device according to Claim 2 , characterized in that the inflows and outflows (12, 13) for pressure fluid are arranged in an axial end region of the shift rod (8). Device according to one of the Claims 1 until 3 , characterized in that the separating element (15) is designed as a tube which is inserted coaxially into the shift rod (8). Device according to one of the Claims 1 until 3 , characterized in that the separating element (15) has at one axial end (16) two axially spaced locking elements (17, 18) which are each tightly connected to the shift rod (8) on its inner surface, the separating element (15 ) has at least one fluid opening (19) between the two blocking elements (17, 18). Device according to Claim 5 , characterized in that the one locking element (17) is arranged axially at the level of the piston (4). Device according to Claim 5 , characterized in that the locking elements (17, 18) are designed as cylindrical bodies which have at least one sealing element (20) on their outer circumference which rests against the inner surface of the shift rod (8). Device according to Claim 1 , characterized in that the shift rod (8) axially on both sides of the piston (4) has at least one passage (21, 22) for pressure fluid. Device according to Claim 4 , characterized in that the separating element (15) inserted into the shift rod (8) and designed as a tube is held and sealed in the axial end region of the shift rod (8) by a terminating piece (23) which is enlarged in diameter and rests on the inner circumference of the shift rod (8) will. Device according to Claim 5 or 9 , characterized in that the locking elements (17, 18) and / or the terminating piece (23) is formed in one piece with the separating element (15). Device according to Claim 10 , characterized in that the component consisting of the separating element (15), locking elements (17, 18) and terminating piece (23) is designed as a unit which can be pushed into the tubular switching rod (8).

Images