DE102013102199A1 - Cylinder with path measuring device - Google Patents

Abstract

The description comprises a cylinder for power transmission of a steering support of a vehicle comprising: a piston 13 with a piston rod 7, wherein the piston 13 is translationally movable by pneumatic or hydraulic pressures within the cylinder, the cylinder further comprising: a means 11 for deflecting the translational Movement of the piston 13 in a rotational movement and a rotational angle sensor 10 for measuring the rotational movement.

Description

FIELD OF THE INVENTION

The present invention relates to a cylinder for power transmission of a steering assist of a vehicle and a steering system with a steering assist for a vehicle.

BACKGROUND OF THE INVENTION

In the prior art cylinders are known for power transmission, which have a displacement measurement of the piston outside the cylinder. The path measurement is performed by placing a sensor on the outer wall of the cylinder and tracking the movement of a magnet mounted on the piston.

SUMMARY OF THE INVENTION

For a displacement measurement to work with a sensor on the outer wall of the cylinder tracking the movement of a magnet on the piston, the cylinder wall must be made of a non-magnetic material. A suitable material would be, for example, plastic, aluminum, non-magnetic steel or austenitic cast iron. However, high wall thicknesses are required for low strength materials such as plastic or aluminum, so that the cylinder is also suitable for high pressures. A high wall thickness of the cylinder means a large distance of the sensor to the magnet of the piston, whereby the measurement accuracy is deteriorated. An alternative would be a non-magnetic steel. Non-magnetic steel is suitable for high pressures even with low wall thickness. However, non-magnetic steel is expensive and difficult to machine.

It is therefore an object to provide a power transmission cylinder which can be made of a low strength material while still withstanding high pressures. In addition, the distance measurement of the stroke of the piston should be accurate.

As a first embodiment of the invention, there is provided a cylinder for power transmitting a steering assist of a vehicle, comprising: a piston having a piston rod, the piston being translatable by pneumatic or hydraulic pressures within the cylinder, the cylinder further comprising: means for Diverting the translational movement of the piston in a rotational movement and a rotational angle sensor for measuring the rotational movement.

Due to the transformation of the translatory lifting movement of a piston of a cylinder into a rotary rotary motion, advantageously rotational angle sensors can be used for measuring the distance of the piston. Advantageously, the rotation angle sensor can be arranged inside the cylinder, whereby the sensor is protected.

As a second embodiment of the invention, a steering system with a steering assistance for a vehicle is provided, wherein the steering system comprises a cylinder according to one of claims 1 to 5.

Exemplary embodiments are described in the dependent claims.

According to an exemplary embodiment of the invention, a cylinder is provided, wherein the rotation angle sensor comprises a spindle whose rotation is detectable by the rotation angle sensor and wherein the spindle is coupled to the piston rod via the means.

In a further embodiment of the invention, a cylinder is provided, wherein the means is a nut, an internal thread or a ball screw thread.

Advantageously, a rotation angle sensor can be used, which can measure more than 360 °, whereby a smaller pitch of the nut, the internal thread or the ball screw and the spindle can be selected and thereby results in a higher resolution of the stroke movement of the piston.

By using a nut or an internal thread, a manufacturing technology simple transformation of the lifting movement can be carried out in a rotary motion. A ball screw is characterized by a very low friction effect.

According to a further embodiment of the present invention, a cylinder is provided, wherein the piston rod has an anti-rotation.

By preventing rotation of the piston rod measuring errors due to rotations, which do not have their cause in a lifting movement avoided. The rotation is obtained with respect to the piston rod to the cylinder tube / the rest of the cylinder. The piston rod is therefore not rotatable because of the rotation in the cylinder tube.

According to an exemplary embodiment of the invention, a cylinder is provided, wherein the rotation by an eccentric arrangement of the piston rod and / or is formed by a design of the piston rod as a square tube or as a profile tube, wherein the piston rod may be formed as a tube or solid material rod.

As an idea of the invention can be considered to provide a cylinder for power transmission, which converts the translational movement of the piston rod in a rotational movement, which can be measured by a rotation angle sensor for the displacement measurement of the piston. Advantageously, in such a cylinder, the wall thickness can be selected independently of a sensor. Thus, a higher pressure within the cylinder is possible, whereby more power can be transmitted. In addition, a corresponding rotation angle sensor can be used for cylinders of different stroke length, so that only one or a few types of rotation angle sensors can be used for a wide variety of cylinders.

Of course, the individual features can also be combined with each other, which can also be partially beneficial effects that go beyond the sum of the individual effects.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details and advantages of the invention will become apparent from the embodiments illustrated in the drawings. Show it

1 a cylinder of the prior art in a perspective view,

2 the cylinder of the prior art in a longitudinal sectional view,

3 a cylinder according to the invention in a longitudinal sectional view,

4 a schematic representation of the cylinder of 3 to illustrate the advantageous arrangement of the terminal and the piston rod on a line.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

1 shows a cylinder 6 of the prior art in a perspective view with pressure connections 1 . 3 , a piston rod 5 , a piston 16 and a mechanical connection 4 , A travel measurement of the stroke takes place via a sensor 2 , outside the cylinder 6 is arranged. This sensor 2 tracks the stroke movement of the piston 16 using one on the piston 16 arranged magnets.

2 shows the same cylinder in a longitudinal section with the piston 16 that is inside the cylinder 6 can perform a translatory movement.

3 shows a cylinder according to the invention with a piston 13 with piston rod 7 that translates along an axis 14 is displaceable. The translational movement of the piston rod 7 is by means of a device / means in a rotational movement of the spindle 9 transformed. The spindle 9 is with a rotation angle sensor 10 connected (positive or non-positive or in one piece), whereby the rotational movement of the spindle 9 through the rotation angle sensor 10 can be detected. Thus, a distance measurement of the translational movement of the piston 13 be enabled. The advantage here is that the wall thickness or the material of the wall of the cylinder is not decisive for the quality of the distance measurement, as is the case with non-contact sensors for measuring the movement of a magnet on the piston. The wall of the cylinder can therefore be chosen from any material and in the required wall thickness, regardless of a sensor for measuring the distance of the piston 13 to have to take.

4 shows a schematic representation of the cylinder of 3 to illustrate the advantageous arrangement of the connection 15 and the piston rod 7 on a line 14 , 4 shows the eccentric piston rod 7 for preventing rotation and the also eccentrically arranged mechanical connection 15 , Due to the uniform eccentricity of the piston rod 7 and the mechanical connection 15 can be advantageously avoided that resulting from external axial forces radial forces that would require a support.

It should be noted that the term "comprising" does not exclude other elements or method steps, just as the term "a" and "an" does not exclude multiple elements and steps.

The reference numerals used are for convenience of reference only and are not to be considered as limiting, the scope of the invention being indicated by the claims.

LIST OF REFERENCE NUMBERS

1

pressure connection

2

Sensor for distance measurement

3

pressure connection

4

mechanical connection

5

piston rod

6

cylinder

7

piston rod

9

spindle

10

Rotation angle sensor

11

Nut or female thread or recirculating ball thread

12

Seal to the sensor room

13

piston

14

axis

15

connection

16

piston

Claims (6)

Cylinder for power transmission of a steering assistance of a vehicle comprising: a piston ( 13 ) with a piston rod ( 7 ), the piston ( 13 ) is translationally movable within the cylinder by pneumatic or hydraulic pressures, characterized in that the cylinder further comprises: a means ( 11 ) for deflecting the translatory movement of the piston ( 13 ) in a rotary motion and a rotation angle sensor ( 10 ) for measuring the rotational movement. Cylinder according to claim 1, characterized in that the rotation angle sensor ( 10 ) a spindle ( 9 ) whose rotation by the rotation angle sensor ( 10 ) is detectable and wherein the spindle ( 9 ) with the piston rod ( 7 ) on the means ( 11 ) is coupled. Cylinder according to one of claims 1 or 2, characterized in that the means ( 11 ) is a nut, an internal thread or a ball screw thread. Cylinder according to one of the preceding claims, characterized in that the piston rod ( 7 ) has an anti-rotation. Cylinder according to claim 4, characterized in that the rotation by an eccentric arrangement of the piston rod ( 7 ) and / or is formed by a design of the piston rod as a square tube or as a profile tube, wherein the piston rod may be formed as a tube or solid material rod.  A steering system with steering assistance for a vehicle, the steering system comprising a cylinder according to one of the preceding claims.

Images