WO2015000481A1

WO2015000481A1 - Piston-cylinder unit

Info

Publication number: WO2015000481A1
Application number: PCT/DE2014/200290
Authority: WO
Inventors: Markus Heitbaum
Original assignee: Schaeffler Technologies Gmbh & Co. Kg
Priority date: 2013-07-04
Filing date: 2014-07-01
Publication date: 2015-01-08
Also published as: DE102014212670A1; DE112014003101A5

Abstract

The invention relates to a piston-cylinder unit having a cylinder and a piston which can be axially displaced in said cylinder and has a piston rod connected to said piston, said piston rod being connectable to an actuator element and being displaceable by means of said actuator element in order to axially displace the piston in the cylinder. Connected to the piston is provided at least one guide element which projects radially outwards and which engages in an axial guide of the cylinder in order to prevent the piston from rotating or being incorrectly positioned in the cylinder.

Description

Piston-cylinder unit

The invention relates to a piston-cylinder unit, such as in particular a master cylinder in particular for a clutch or transmission actuation of a motor vehicle.

Piston-cylinder units have become known in the art as a master cylinder for example for a clutch actuation. In this case, a piston in a cylinder of the piston-cylinder unit is displaced in the axial direction, so that a pressure chamber, which is filled with a fluid, thereby increased or decreased to pressurize the fluid pressure to an aggregate, for example by means of a slave cylinder actuate. For the actuation state of the unit, the position of the piston of the master cylinder of importance, which is why a piston of such a piston-cylinder unit is provided with a sensor nozzle, so that a sensor arranged on the cylinder sensor element can detect the position of the sensor sensor element and thus the piston relative to the sensor receiving element , With this knowledge about the position of the piston in the cylinder of the piston-cylinder unit then an improved control can be performed.

To achieve the best possible resolution for the position of the piston is the

Sensornehmerelement not arranged centrally of the piston, but it is off-center of the piston arranged such that the distance between the sensor pad and the Sensornehmerelement is minimized. However, this involves the risk that the piston is incorrectly inserted into the cylinder during assembly of the piston with the sensor guide element. In this case, the most common error that occurs is that the piston is rotated by 180 ° about its longitudinal axis into the cylinder, which has the effect that the sensor element has the greatest distance with respect to the sensor receiving element. This leads to errors in the position determination or failure of the sensor device.

It is the object of the invention to provide a piston-cylinder unit in which incorrect assembly of the piston can be excluded.

The object of the invention is achieved with the features of claim 1. An embodiment of the invention relates to a piston-cylinder unit having a cylinder and a piston axially displaceable in the cylinder with a piston rod connected to the piston, which is connectable to an actuator element and which is displaceable by means of the actuator element to the piston in the cylinder axially displace, wherein at least one radially outwardly projecting guide member is provided connected to the piston, which engages in an axial guidance of the cylinder to prevent a rotation or mispositioning of the piston in the cylinder. As a result, it is successfully achieved that the piston can only be inserted into the cylinder in one position when the guide element engages in axial guidance, so that rotation of the piston about its longitudinal axis prior to insertion is precluded. This has the effect that the piston is always positioned in such a way that a sensor sensor element provided is positioned as intended with respect to the sensor element.

It is particularly advantageous if the cylinder is designed in several parts, wherein at least two cylinder elements are connected to form the cylinder, wherein the axial guidance is provided in at least one of the cylinder elements. If the cylinder is designed in several parts, it is advantageous if the axial guidance are formed in at least one of the cylinder elements or in a plurality of the cylinder elements. As a result, a secure guidance of the guide element in the axial guidance can be achieved, so that the axial movement of the guide element in the axial guidance over the maximum axial movement of the piston in the cylinder is made possible.

It is particularly advantageous if the cylinder is formed from at least two tubular cylinder elements which are arranged adjacent to each other in the axial direction and connected to each other. It is particularly advantageous if one of the tubular cylinder elements is open on one side for receiving the piston, while at least the second cylinder element is ausgenbildet open on both sides as a tubular cylinder element to accommodate the piston axially displaceable.

It is also advantageous if the axial guidance of the cylinder is a groove in a wall of the cylinder or in at least one of the cylinder elements. Alternatively, the axial guide can also be formed by at least one web which cooperates with the guide element in order to guide the piston in the circumferential direction so as to be non-rotatable with respect to the longitudinal axis. It is also advantageous if for connecting the piston with the piston rod

Connecting element is provided, which forms a positive connection with both the piston and the piston rod. This allows a simple coupling can be achieved, which can be implemented quickly and inexpensively with the connecting element.

It is also advantageous if the connecting element has the at least one projecting guide element which projects radially outward and engages in the axial guidance. Thus, in addition to ensuring the connection, the connecting element can also assume a further function, which is particularly advantageous because it requires no further component.

To achieve the Unverdrehbarkeit it is advantageous if the connecting element engages positively in a receptacle of the piston, wherein the receptacle of the piston in the axial direction of the piston is open, for inserting the connecting element into the receptacle. The one-sided open recording a quick coupling is achieved.

It is also advantageous if the receptacle has a non-rotationally symmetrical cross-sectional area which corresponds to the cross-section of the connecting element, so that the connecting element in the receptacle is arranged substantially non-rotatable with respect to the longitudinal axis of the piston. Any shape which deviates from a circular shape and thus does not lead to a twistability is regarded as non-rotationally symmetrical. Deviations from a circular shape by protrusions or circular sections etc. are particularly preferred.

It is also advantageous if the connecting element has first means for the positive connection of the piston rod with the connecting element, wherein the piston rod has second means for positive connection of the piston rod with the connecting element, wherein the first means and the second means cooperate with each other such that the Piston rod relative to the connecting element is substantially non-rotatable with respect to the longitudinal axis of the piston.

It is particularly advantageous if the first means are slots in the connecting element and the second means are webs of the piston rod, which engage in the slots. So can be achieved in a simple manner, a coupling in which the piston rod still has a certain play perpendicular to the longitudinal axis of the piston.

The present invention will be explained in more detail below with reference to preferred exemplary embodiments in conjunction with the associated figures:

Showing:

FIG. 1 shows a perspective view of a piston-cylinder unit according to the invention,

FIG. 2 shows a view of the connecting element,

FIG. 3 is a view of a cylinder element,

FIG. 4 shows a view of the piston with connecting element,

FIG. 5 shows a sectional view with piston and connecting element,

FIG. 6 shows a sectional view with piston and connecting element,

FIG. 7 shows a sectional view with piston and connecting element,

8 shows a sectional view with piston and connecting element, and

Figure 9 is a sectional view with piston and connecting element.

FIG. 1 shows a piston-cylinder unit 1 with a cylinder 2 and a piston 3 axially displaceably received in the cylinder 2. The piston 3 is connected to a piston rod 4 so that the piston 3 is actuated by means of an actuator element, not shown, such as a foot pedal or a drive unit is connectable, which can displace the piston 3 in the axial direction within the cylinder 2. The piston 3 is formed with a sensor element 5, which is arranged in a receptacle of the piston 3. At the cylinder 2, a sensor receiving element 6 is arranged, which detects the position of the sensor element 5.

The piston 3 is connected to the piston rod 4 via a connecting element 7. The connecting element 7 engages in a recess of the piston 3, so that a projection 8 of the connecting element 7 can engage in the recess 9 of the piston 3 to be secured there. For this purpose, the projection 8 of the connecting element 7 is preferably formed with locking elements, which engage in the recess 9 of the piston 3 and cause a secure connection between the piston 3 and the connecting element 7.

With the connecting element 7, the piston rod 4 can be connected for example via a kind of ball head. For this purpose, it preferably matures in a type of pan of the connecting element 7, so that the piston rod can be tilted relative to the pan or to the connecting element.

The cylinder 2 is formed in two parts in the exemplary embodiment, so that a first

Cylinder member 10 is sealed with a second cylinder element connectable to define the cylinder interior, which receives the piston. For this purpose, the cylinder element 10 has a recess 12 with a collar into which the cylinder element 1 1 can be inserted at least partially in the axial direction, wherein a sealing element 13 is provided, for sealing between the first cylinder element 10 and the second cylinder element 1 first

2 shows the connecting element 10 in a perspective view with the projection 8 extending in the axial direction and a basket-like structure 14 as a socket of the connecting element 7, which is divided by slots 15 into individual tongues 16. On one of the tongues 16 a projecting guide element 17 is formed, which serves to cooperate with an axial guide in order to prevent a rotation of the piston 3 or an undefined positioning of the piston when inserted into the cylinder 2. The basket-like structure 14 of the connecting element 7 is not formed rotationally symmetrical, wherein the receptacle of the piston 3 is not rotationally symmetrical, so that a rotation of the connecting element 7 in the recess 9 is received untwisted. 3 shows the second cylinder element 1 1, which is formed substantially hollow cylindrical. On the inner wall, an axial guide 18 is formed as a groove into which the guide element 17 of the connecting element 7 can engage.

4 shows the piston 3 with the connecting element 7 and the piston rod 4, wherein the connecting element 7 can be inserted into the recess 9 of the piston. In this case, the connecting element 7 is positioned such that the guide element 17 protrudes radially outward, even if the connecting element 7 is inserted into the recess 9 of the piston 3.

Figures 5 and 6 show the arrangement of the piston 3 in the cylinder 2 and in the arrangement of the cylinder member 1 1 with the connecting element 7 and the piston rod 4. The connecting element 7 with the guide member 17 projects radially outwardly beyond the radial extent of the piston 3 addition and engages in the axial guide 18 in the inner wall of the cylinder member 1 1 a. In FIG. 5, the piston 3 is placed so that it is inserted into the cylinder 2, wherein the guide element 17 begins to be received in the axial guide 18.

In Figure 6, the piston 3 is inserted so far into the cylinder 2, that the guide member 17 has substantially reached a stop of the axial guide in the axial direction.

FIG. 7 once again shows the receptacle of the guide element 17 in the axial guide 18 of the piston 3 in a detailed representation.

FIG. 8 shows the arrangement of the cylinder element 11 with the embodiment 18 designed as a groove into which the guide element 17 engages in a radially outward engagement.

FIG. 9 shows the arrangement of the guide element 17 in the axial guide 18 when the piston 3 has been pushed in substantially completely. LIST OF REFERENCE NUMBERS

Piston-cylinder unit

cylinder

piston

piston rod

Sensor transmitter element

Sensor receiving element

connecting element

head Start

recess

cylindrical member

recess

sealing element

structure

slot

tongues

guide element

axial guidance

Claims

claims

1 . Piston-cylinder unit (1) with a cylinder (2) and in the cylinder (2) axially displaceable piston (3) with a piston (3) connected to the piston rod (4) which is connectable to an actuator element and which by means of Aktuato- is relocatable elements to axially displace the piston (3) in the cylinder (2), wherein with the piston (3) at least one radially outwardly projecting guide member (17) is provided, which in an axial guide (18) of the cylinder (2) engages to prevent a rotation or mispositioning of the piston (3) in the cylinder (2).

Second piston-cylinder unit (1) according to claim 1, characterized in that the cylinder (2) is formed in several parts, wherein at least two cylinder elements (10,11) are connected to form the cylinder (2), wherein the axial guide ( 18) is provided in at least one of the cylinder elements.

3. piston-cylinder unit according to claim 2, characterized in that the cylinder (2) of at least two tubular cylinder elements (10,11) is formed, which are arranged adjacent to each other in the axial direction and connected to each other.

4. piston-cylinder unit according to claim 1, 2 or 3, characterized in that the axial guide (18) of the cylinder (2) is a groove in a wall of the cylinder (2) or in at least one of the cylinder elements (10,11) ,

5. Piston-cylinder unit according to one of the preceding claims, characterized in that for the connection of the piston (3) with the piston rod (4), a connecting element (7) is provided, which a positive connection with both the piston (3) and the piston rod (4) is received.

6. piston-cylinder unit according to claim 5, characterized in that the connecting element (7) has the at least one projecting guide element (17) which projects radially outward and engages in the axial guide (18).

7. Piston-cylinder unit according to claim 5 or 6, characterized in that the connecting element (7) engages positively in a receptacle of the piston (3), wherein the receiving of the piston in the axial direction of the piston is open, for inserting the connecting element (7) in the receptacle.

8. piston-cylinder unit according to claim 7, characterized in that the receptacle has a non-rotationally symmetrical cross-sectional area which corresponds to the cross section of the connecting element (7), so that the connecting element in the receptacle with respect to the longitudinal axis of the piston (3) substantially non-rotatable is arranged.

9. Piston-cylinder unit according to one of claims 5, 6, 7 or 8, characterized in that the connecting element (7) has first means for the positive connection of the piston rod (4) with the connecting element (7), wherein the piston rod (4 ) second means for positive connection of the piston rod (4) with the connecting element (7), wherein the first means and the second means cooperate with each other such that the piston rod relative to the connecting element is substantially non-rotatable with respect to the longitudinal axis of the piston.

10. Piston-cylinder unit according to claim 9, characterized in that the first means are slots in the connecting element (7) and the second means are webs of the piston rod (4) which engage in the slots.