Position detecting device and industrial vehicle having the position detecting device

• US 6,463,009 B1
• Filed: 08/23/2000
• Issued: 10/08/2002
• Est. Priority Date: 08/26/1999
• Status: Expired due to Fees

• Current Assignee: Honda Electronics Co., Ltd., Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
• Original Assignee: Honda Electronics Co., Ltd., Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
• Inventors: Yagita, Yasunobu, Nagai, Katsumi
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US09/644,738
• Time in Patent Office: 776 Days
• Field of Search: 367/99, 367/902, 367/900, 367/13
• US Class Current: 367/99
• CPC Class Codes: B66F 9/0755 Position control; Position detectors
• CPC Class Codes: B66F 9/20 Means for actuating or controlling masts, platforms, or forks power take-off from vehicle transmissions, combined with vehicle propulsion systems B60K
• CPC Class Codes: F15B 15/2884 using sound, e.g. ultrasound
• CPC Class Codes: G01S 7/52006 with provision for compensating the effects of temperature
• CPC Class Codes: G01S 7/524 Transmitters
• CPC Class Codes: Y10S 367/902 Speed of sound compensation

Abstract

In a position detecting device which detects a piston rod based on the time elapsed from a point at which an ultrasonic wave is emitted from an ultrasonic wave sensor toward a lower end surface of the piston rod reciprocatingly moved linearly by supply and discharge of a working oil with respect to a hydraulic cylinder to a point at which the ultrasonic wave reflected by the lower end surface of the piston rod is received by the ultrasonic wave sensor, if the working oil'"'"'s temperature is detected by a temperature sensor, then a microcomputer sets the strength of the ultrasonic wave emitted from the ultrasonic wave sensor in accordance with the temperature of the working oil so as to accurately detect the position of the piston.

Claims

1. A position detecting device for detecting a position of a movable member, which moves within a hydraulic cylinder, by using an ultrasonic wave, the device comprising:

an ultrasonic wave sensor which emits the ultrasonic wave toward the movable member and receives the ultrasonic wave reflected by the movable member;

position calculating means for counting a time elapsed from an emission of the ultrasonic wave to a reception of the reflected ultrasonic wave by the ultrasonic wave sensor to calculate a position of the movable member relative to the ultrasonic wave sensor on the basis of the time elapsed thus counted;

a temperature sensor which detects a temperature of fluid through which the ultrasonic wave is propagated within the cylinder; and

reception sensitive level setting means for variably setting a reception sensitive level for the ultrasonic wave received by the ultrasonic wave sensor, wherein the reception sensitive level setting means sets the reception sensitive level for the ultrasonic wave based on the temperature of the fluid detected by the temperature sensor, so as to include a range in which it is made consecutively higher as the temperature of the fluid detected by the temperature sensor is made higher.

2. An industrial vehicle having the position detecting device according to claim 1.

3. A position detecting device for detecting a position of a movable member, which moves within a hydraulic cylinder, by using an ultrasonic wave, the device comprising:

an ultrasonic wave sensor, which emits the ultrasonic wave toward the movable member and receives the ultrasonic wave reflected by the movable member;

position calculating means for counting a time elapsed from an emission of the ultrasonic wave to a reception of the reflected ultrasonic wave by the ultrasonic wave sensor to calculate a position of the movable member relative to the ultrasonic wave sensor on the basis of the time elapsed thus counted;

a temperature sensor which detects a temperature of fluid through which the ultrasonic wave is propagated within the cylinder; and

ultrasonic wave strength setting means for variably setting a strength of the ultrasonic wave emitted from the ultrasonic wave sensor, wherein the ultrasonic wave strength setting means sets the strength of the ultrasonic wave based on the temperature of the fluid detected by the temperature sensor, so as to be smaller in a step-wise manner as the temperature of the fluid detected by the temperature sensor is made higher.

5. The position detecting device according to claim 3, further comprising:

storage means for storing the position of the movable member as the latest position data each time after the position of the movable member is calculated,

the ultrasonic wave strength setting means setting the strength of the ultrasonic wave based on the latest position data.

6. The position detecting device according to claim 5, wherein the ultrasonic wave strength setting means sets the strength of the ultrasonic wave so as to be made larger as the position of the movable member based on the latest position data is further from the ultrasonic wave sensor.

4. A position detecting device for detecting a position of a movable member, which moves within a hydraulic cylinder, by using an ultrasonic wave, the device comprising:

an ultrasonic wave sensor, which emits the ultrasonic wave toward the movable member and receives the ultrasonic wave reflected by the movable member;

position calculating means for counting a time elapsed from an emission of the ultrasonic wave to a reception of the reflected ultrasonic wave by the ultrasonic wave sensor to calculate a position of the movable member relative to the ultrasonic wave sensor on the basis of the time elapsed thus counted;

a temperature sensor which detects a temperature of fluid through which the ultrasonic wave is propagated within the cylinder; and

ultrasonic wave strength setting means for variably setting a strength of the ultrasonic wave emitted from the ultrasonic wave sensor, wherein the ultrasonic wave strength setting means sets the strength of the ultrasonic wave based on the temperature of the fluid detected by the temperature sensor, so as to include a range in which it is made consecutively smaller as the temperature of the fluid detected by the temperature sensor is made higher.

7. An industrial vehicle having the position detecting device according to claim 4.

8. A position detecting device for detecting a position of a movable member, which moves within a hydraulic cylinder, by using an ultrasonic wave, the device comprising:

an ultrasonic wave sensor which emits the ultrasonic wave toward the movable member and receives the ultrasonic wave reflected by the movable member;

position calculating means for counting a time elapsed from an emission of the ultrasonic wave to a reception of the reflected ultrasonic wave by the ultrasonic wave sensor to calculate a position of the movable member relative to the ultrasonic wave sensor on the basis of the time elapsed thus counted;

a temperature sensor which detects a temperature of fluid through which the ultrasonic wave is propagated within the cylinder; and

reception sensitive level setting means for variably setting a reception sensitive level for the ultrasonic wave received by the ultrasonic wave sensor, wherein the reception sensitive level setting means sets the reception sensitive level for the ultrasonic wave based on the temperature of the fluid detected by the temperature sensor, so as to be made higher in a step-wise manner as the temperature of the fluid detected by the temperature sensor is made higher.

9. The position detecting device according to claim 8, further comprising:

storage means for storing the position of the movable member as the latest position data each time after the position of the movable member is calculated,

the reception sensitive level setting means setting the reception sensitive level for the ultrasonic wave based on the latest position data.

10. The position detecting device according to claim 9, wherein the reception sensitive level setting means sets the reception sensitive level of the ultrasonic wave so as to be made smaller as the position of the movable member based on the latest position data is further from the ultrasonic wave sensor.