Displacement measuring system for a piston-cylinder assembly

• US 20050066536A1
• Filed: 08/18/2004
• Published: 03/31/2005
• Est. Priority Date: 09/27/2003
• Status: Active Grant

• Current Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Hildner, Stefan, Thoma, Achim, Kolb, Wolfgang
• Granted Patent: US 7,204,035 B2
• Time in Patent Office: Days
• US Class Current: 33/706
• CPC Class Codes: F15B 15/2892 characterised by the attachment means
• CPC Class Codes: F16F 2230/08 Sensor arrangement
• CPC Class Codes: F16F 9/3207 Constructional features F16F9/34 - F16F9/50 take precedence; assembly or repair F16F9/3271

Abstract

A piston rod is guided with freedom of axial movement in a cylinder, where the position of the piston rod is detected by a first position-measuring device, which travels along with the piston rod, and by a second position-measuring device on the cylinder side. The two position-measuring devices are radially adjacent and axially parallel, and are supported in such a way that they cannot rotate with respect to each other.

Claims

1. A displacement measuring system for a piston-cylinder assembly, the system comprising:

a cylinder;

a piston rod guided for movement axially within the cylinder;

a first position measuring device which moves with the piston rod and is fixed against circumferential movement with respect to the cylinder; and

a second position measuring device fixed to the cylinder radially adjacent and axially parallel to the first position measuring device, the first and second positioning measuring devices being fixed against circumferential movement with respect to each other.

2. A displacement measuring system as in claim 1 further comprising a holder for the second position measuring device, the holder having guide surfaces which prevent circumferential movement of the first position measuring device relative to the second position measuring device.

3. A displacement measuring system as in claim 1 further comprising a protective sleeve which surrounds the cylinder and moves with the piston rod, the first position measuring device moving with the sleeve.

4. A displacement measuring system as in claim 3 wherein the first position measuring device is fixed to the sleeve.

5. A displacement measuring device as in claim 4 wherein the sleeve has a receiving channel in which the first position measuring device is fixed.

6. A displacement measuring system as in claim 5 wherein the sleeve has anti-rotation surfaces which prevent circumferential movement of the sleeve with respect to the cylinder.

7. A displacement measuring system as in claim 6 further comprising a holder for the second position measuring device, the holder having guide surfaces which cooperate with the anti-rotation surfaces on the sleeve to prevent circumferential movement of the first position measuring device relative to the second position measuring device.

8. A displacement measuring system as in claim 3 further comprising a spring which axially pretensions the first position measuring device against the sleeve.

9. A displacement measuring device as in claim 8 a holder for the second position measuring device, the holder having a receiving channel in which the spring and the first position measuring device are received, the first position measuring device being axially moveable in the channel.