Device for measuring distance

• US 6,698,289 B1
• Filed: 10/16/2001
• Issued: 03/02/2004
• Est. Priority Date: 12/21/1998
• Status: Expired due to Fees

• Current Assignee: TRW Automotive Electronics & Components GmbH & Co. KG
• Original Assignee: TRW Automotive Electronics & Components GmbH & Co. KG
• Inventors: Hora, Peter, Lemcke, Sören
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): SAINT SURIN, JACQUES M
• Application Number:
  US09/868,714
• Time in Patent Office: 868 Days
• Field of Search: 735/97, 735/98, 736/00, 736/02, 732/90.V, 73/17.3, 73/17.9, 732/90.R, 736/27, 736/28, 367/122, 367/127, 367/129
• US Class Current: 73/597
• CPC Class Codes: G01B 17/00 Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations

Abstract

The invention relates to a device for distance measurement, comprising a transmission element (9) for emitting pulsed acoustic or electromagnetic waves. Said transmission element is provided at a first end of a distance (L) or at a known distance from said first end. The device contains a receiving element (13) for the emitted waves. Said receiving element (13) receives said waves at a second end of the distance (L) or, after reflection at the second end, at the first end. An evaluation and control unit (11) calculates the distance (L) from the running time and the signal speed. According to the invention, a telescope tube (3) with two engaging tube elements (5, 7) is used between the first and second end. The transmission element (9) and the receiving element (13) are arranged on the tube elements (5, 7) respectively or are coupled thereto via waveguides. One of the tube elements can also be coupled to a displaceable element which can change location.

Claims

1. A device for measuring distance comprising:

an ultra-sound transmitter element adapted to emit acoustical waves, the transmitter element being disposed at a first end of a distance (L) to be measured and having a face surface defining a first diameter;

an ultra-sound receiver element adapted to receive the emitted acoustical waves, which is provided at the other end of the distance (L) to be measured;

an evaluation and control unit operative to control the transmitter and communicate with the receiver, whereby the distance (L) to be measured is determined from a transit time of the acoustical waves and a velocity of the acoustical waves; and

,

a telescope tube having a first part displaceably arranged inside a second part, said telescope tube being operatively connected on a first end with the transmitter element and on a second end with the receiver element whereby said acoustical waves emitted by the transmitter at said first end of said distance L pass through at least a portion of the telescope tube and are received by the receiver said first end of the telescope tube having a second diameter smaller than said first diameter of the transmitter element.

2. Device according to claim 1, wherein the telescope tube defines an annular compartment adapted to receive said transmitter element, the annular compartment being filled with damping material.

3. Device according to claim 1 wherein said telescope tube is a wave-guide, and further including an additional ultra-sound receiver element connected with the wave-guide, the evaluation- and control unit being adapted to determine from the known distance between the ultra-sound transmitter element and the additional ultra-sound receiver element, the signal velocity and/or changes in the signal velocity and utilize same for the determination of the distance (L) from the signal transit time recorded by means of the ultra-sound transmitter element and the ultra-sound receiver element.

4. Device according to claim 1 further including a second ultra-sound receiver element wherein the evaluation and control unit is adapted to determine from the known distance between the ultra-sound receiver element and the additional ultra-sound receiver element the signal velocity and/or changes in the signal velocity and utilizes for determination of the distance (L) the signal transit time recorded by means of the ultra-sound transmitter element and the ultra-sound receiver element.

5. Device according to claim 1 wherein the ultra-sound transmitter element and the ultra-sound receiver element are arranged in the axis (A) of the telescope tube for joining the ultra-sound transmitter element and/or the ultra-sound receiver element with the telescope tube, are essentially connected with same in the axis (A) of the telescope tube.

6. Device according to claim 1 wherein peripheral walls of the telescope tube have perforations for damping of reflections.

7. Device according to claim 1 wherein the ultra-sound transmitter element and the ultra-sound receiver element are an integrated ultra-sound transmitter/receiver element.

8. Device according to claim 1 wherein the evaluation and control unit is designed as an integrated component of the telescope tube.

9. Device according claim 1 wherein the evaluation and control unit is disposed inside the telescope tube.

10. A device for measuring a distance comprising:

a transmitter element;

a telescopic tube having a first tube element operatively connected with the transmitter element, and having a second tube element slidably coupled with the first tube element;

a receiver element arranged to receive a signal transmitted by the transmitter element after said signal traverses a path that passes through at least a portion of the first tube element and that passes through at least a portion of the second tube element, a length of said signal path being adjustable based on a relative position between the first and the second tube elements; and

an evaluation-and-control unit in operative communication with the transmitter element and the receiver element, said evaluation-and-control unit being adapted to perform the steps of;

selectively operate the transmitter element to transmit said signal,

communicate with the receiver element to detect the reception of said signal by the receiver element,

evaluate the signal received by the receiver element to obtain a transit time between the signal transmission and the signal reception, and

extract the distance to be measured based on the transit time, a pre-determined signal velocity, and a pre-determined equation that relates said distance with the transit time and the signal velocity.

11. The device as set forth in claim 10, wherein:

the transmitter element includes an ultra-sonic transmitter adapted to generate an ultra-sonic signal; and

the receiver element includes an ultra-sonic receiver.

12. The device as set forth in claim 11 wherein the ultra-sonic transmitter element and the ultra-sonic receiver element are formed as a single unitary ultra-sound converter.

13. The device as set forth in claim 11, wherein a connection of the transmitter element with the first tube element includes:

a conically expanding annular compartment disposed at an end of the first tube element in alignment with a membrane of the ultra-sonic transmitter to couple the ultra-sonic signal with the first tube element.

14. The device as set forth in claim 13, further comprising a damping material disposed in the annular compartment.

15. The device as set forth in claim 10, wherein a connection of the transmitter element with the first tube element includes a waveguide disposed therebetween.

16. The device as set forth in claim 10, further comprising:

a second receiver element in operative communication with the evaluation-and-control unit and with the telescopic tube.

17. The device as set forth in claim 16, wherein:

the second receiver element is disposed at an operative distance from the transmitter element; and

the evaluation-and-control unit is further adapted to perform the steps of;

selectively operate the transmitter element to transmit a calibrating signal,

communicate with the second receiver element to detect the reception of said calibrating signal by the second receiver element,

evaluate the calibrating signal received by the second receiver element to obtain a calibrating signal transit time, and

obtain the pre-determined signal velocity based on the calibrating signal transit time and a calibration equation that relates the signal velocity with the calibrating signal transit time.

18. The device as set forth in claim 17, wherein the calibration equation is:

$v_s=\frac{L_1}{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>t_1}$

where L₁ is the operative distance between the transmitter and the second receiver, Δ

t₁ is the calibrating signal transit time, and v_s is the obtained pre-determined signal velocity.

19. The device as set forth in claim 16, wherein:

the second receiver element is disposed at an operative distance from the receiver element; and

the evaluation-and-control unit is further adapted to perform the steps of;

selectively operate the transmitter element to transmit a calibrating signal,

communicate with the receiver element to detect the reception of said calibrating signal by the receiver element,

communicate with the second receiver element to detect the reception of said calibrating signal by the second receiver element,

evaluate the calibrating signal received by the receiver element and the second receiver element to obtain a calibrating signal transit time, and

obtain the pre-determined signal velocity based on the calibrating signal transit time and a calibration equation that relates the signal velocity with the calibrating signal transit time.

20. The device as set forth in claim 10, wherein a connection between the second receiver element and the telescope tube includes a waveguide disposed therebetween.

21. The device as set forth in claim 10, wherein:

the transmitter element and the receiver element are arranged at opposite ends of the telescope tube; and

the pre-determined equation that relates said distance with the transit time and the signal velocity is;

22. The device as set forth in claim 10, wherein:

the transmitter element and the receiver element are arranged at the same end of the telescope tube;

the second tube element includes a reflective surface arranged to reflect the transmitted signal toward the receiver element; and

the pre-determined equation that relates said distance with the transit time and the signal velocity is;

23. The device as set forth in claim 10 wherein the transmitter element and the receiver element are arranged along a central longitudinal axis defined by the telescopic tube.

24. The device as set forth in claim 10 further comprising perforations formed on at least a portion of the peripheral walls of the telescope tube, said perforations damping signal reflections off of said peripheral walls.

25. The device as set forth in claim 10 wherein the evaluation-and-control unit is integrated into the telescopic tube.

26. The device as set forth in claim 10 wherein the evaluation-and-control unit is disposed inside the telescopic tube.

27. A device for measuring a distance comprising:

a telescope tube having displaceably interconnected first and second tube elements;

an ultra-sonic transmitter operatively connected with the first tube element;

an ultra-sonic receiver element operatively connected with one of the first and the second tube elements; and

an evaluation-and-control unit in operative communication with the transmitter element and the receiver element, said evaluation-and-control unit selectively operating the transmitter element to transmit an ultra-sonic signal into the telescope tube;

detecting reception at the receiver element of the ultrasonic signal after said signal passes through at least a portion of the second tube element;

deriving a signal path length from the signal transit time and a signal velocity; and

, calculating the distance to be measured based on the signal path length and the geometrical relationship between the transmitter, receiver, and telescope tube.

28. The device for measuring a distance as set forth in claim 27, further comprising:

a second ultra-sonic receiver arranged in operative communication with the telescope tube.

29. The device for measuring a distance as set forth in claim 28, wherein the evaluation-and-control unit is adapted to:

detect reception at the second receiver element of the ultrasonic signal after said signal passes through at least a portion of the second tube element,

obtain a calibration time corresponding to a time interval between detecting reception at the second receiver and one of detecting reception at the receiver and selectively operating the transmitter element, and

calculate the signal velocity based on the calibration time and a pre-determined calibration signal path length.