Height sensor and air spring apparatus incorporating the same in the air chamber

• US 5,859,692 A
• Filed: 05/16/1997
• Issued: 01/12/1999
• Est. Priority Date: 05/16/1997
• Status: Expired due to Fees

• Current Assignee: Rochester Gauges Incorporated
• Original Assignee: Rochester Gauges Incorporated
• Inventors: Ross, Herbert G. Jr., Horvath, Agoston
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/857,393
• Time in Patent Office: 606 Days
• Field of Search: 356/4.01, 356/4.08, 280/707, 267/64.21, 267/64.19
• US Class Current: 356/4.01
• CPC Class Codes: B60G 17/01933 Velocity, e.g. relative velocity-displacement sensors
• CPC Class Codes: B60G 2202/152 Pneumatic spring
• CPC Class Codes: B60G 2204/111 on pneumatic springs
• CPC Class Codes: B60G 2204/126 Mounting of pneumatic springs
• CPC Class Codes: B60G 2204/4502 using resilient buffer
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2401/00 Indexing codes relating to the type of sensors based on the principle of their operation
• CPC Class Codes: B60G 2401/12 Strain gauge
• CPC Class Codes: B60G 2401/14 Photo or light sensitive means, e.g. Infrared
• CPC Class Codes: F16F 2230/08 Sensor arrangement
• CPC Class Codes: F16F 9/05 the flexible wall being of the rolling diaphragm type

Abstract

An air spring apparatus with an internal height sensor is provided. The air spring includes an end cap member, a piston member and a flexible annular sleeve connected therebetween forming a sealed air chamber. The height sensor includes a sensing element and an indicating element and is mounted within the air chamber. The sensing element is mounted to one of the end cap member and piston member. The indicating element has a first portion connected to the end cap member, a second portion connected to the piston member, and an elastic member connected therebetween. The length of the elastic member defines an indicating level sensible by the sensing element such that movement of the end cap member relative to the piston member produces a much smaller proportional movement of the indicating level relative to the sensing element. This proportion reduction of movement allows a smaller sensor to measure a relatively large change in height.

Claims

1. An air spring apparatus with a height sensor, comprising:

an air spring including an end cap member, a piston member, and a flexible annular sleeve connected therebetween forming a sealed air chamber;

a height sensor being mounted within said air chamber including a sensing element and an indicating element;

said sensing element being mounted to one of said end cap member and said piston member;

said indicating element having a first portion connected to said end cap member, a second portion connected to said piston member, and an elastic member connected therebetween and having a variable length;

said length of said elastic member defining an indicating level sensible by said sensing element;

wherein a movement of said end cap member relative to said piston member produces a proportional movement of said indicating level relative to said sensing element.

2. An air spring apparatus with a height sensor according to claim 1, wherein said indicating element further comprises:

a reservoir member constituting said first portion of said indicating element connected to said end cap member;

said reservoir member having a top wall, a side wall, and a bottom wall defining a measurement cavity therewithin and moving with said end cap member;

said bottom wall having a passage formed therethrough;

an elastic tube member constituting said elastic member of said indicating element;

said tube member having an upper end, a lower end, and an inner diameter defining a tube cavity therewithin and having a tube capacity;

said upper end of said tube member being connected to said bottom wall of said reservoir member at said passage to form a fluid connection between said reservoir member and said tube member;

said lower end of said tube member being connected to said second portion of said indicating element to move with said piston element; and

a fluid material disposed within said measurement cavity and said tube cavity and having a free surface within said reservoir member defining said indicating level;

wherein, upon movement of said upper end of said tube member relative to said lower end of said tube member, the tube capacity changes to exchange said fluid material between said reservoir member and said tube member to move the position of said indicating level within said reservoir member in proportion to movement of said end cap member relative to said piston member.

3. An air spring apparatus with a height sensor according to claim 2, wherein said sensing element further comprises:

a capacitance-type level indicator mounted to said top wall of said reservoir member and extending downwardly into said fluid.

4. An air spring apparatus with a height sensor according to claim 2, wherein said sensing element further comprises:

a resistance-type level indicator mounted to said reservoir member and contacting said fluid.

5. An air spring apparatus with a height sensor according to claim 2, wherein said sensing element further comprises:

a distance-measuring device mounted to said top wall of said reservoir member and sensing a distance to said free surface of said fluid.

6. An air spring apparatus with a height sensor according to claim 5, wherein said distance measuring device is an opto-electric device using light to sense said distance to said free surface of said fluid.

7. An air spring apparatus with a height sensor according to claim 5, wherein said distance measuring device is an ultrasonic device using sound to sense said distance to said free surface of said fluid.

8. An air spring apparatus with a height sensor according to claim 1, wherein said elastic member of said indicating element further comprises:

an upper spring member, a lower spring member, and a pointer member;

said upper spring member connected between said first portion of said indicating element and said pointer member;

said upper spring member having a first free length and a first spring constant;

said pointer member being connected between said upper spring member and said lower spring member and defining an indicating level;

said lower spring member being connected between said pointer member and said second portion of said indicating element;

said lower spring member having a second free length and a second spring constant;

said first and second free lengths and said first and second spring constants adapted to position said pointer member adjacent said sensing element;

wherein, upon movement of said first portion of said indicator member relative to said second portion of said indicator member, the position of said pointer member changes relative to said sensing element in proportion to movement of said end cap member relative to said piston member.

9. An air spring apparatus with a height sensor according to claim 8, wherein said sensing element further comprises:

a variable resistor mounted to said first portion of said indicator member.

10. A height sensor for measuring the change in height between two surfaces, comprising:

a sensing element being mounted to one of a first surface and a second surface, said surfaces separated by a first height;

an indicating element having a first portion connected to said first surface, a second portion connected to said second surface, and an elastic member connected therebetween and having a range of lengths;

each said length of said elastic member defining a different indicating level sensible by said sensing element;

wherein a change in height of said first surface relative to said second surface produces a proportional change of said indicating level relative to said sensing element; and

wherein said indicating element further comprises;

a reservoir member constituting said first portion of said indicating element connected to said first surface;

said reservoir member having a top wall, a side wall, and a bottom wall defining a measurement cavity therewithin and moving with said first surface;

said bottom wall having a passage formed therethrough;

an elastic tube member constituting said elastic member of said indicating element;

said tube member having an upper end, a lower end, and an inner diameter defining a tube cavity therewithin and having a tube capacity;

said upper end of said tube member being connected to said bottom wall of said reservoir member at said passage to form a fluid connection between said reservoir member and said tube member;

said lower end of said tube member being connected to said second portion of said indicating element to move with said second surface; and

a fluid material disposed within said measurement cavity and said tube cavity and having a free surface within said reservoir member defining said indicating level;

wherein, upon movement of said upper end of said tube member relative to said lower end of said tube member, the tube capacity changes to exchange said fluid material between said reservoir member and said tube member to move the position of said indicating level within said reservoir member in proportion to movement of said first surface relative to said second surface.

11. A height sensor for measuring the change in height between two surfaces, comprising:

a sensing element being mounted to one of a first surface and a second surface, said surfaces separated by a first height;

an indicating element having a first portion connected to said first surface, a second portion connected to said second surface, and an elastic member connected therebetween and having a range of lengths;

each said length of said elastic member defining a different indicating level sensible by said sensing element;

wherein a change in height of said first surface relative to said second surface produces a proportional change of said indicating level relative to said sensing element; and

wherein said elastic member of said indicating element further comprises an upper spring member, a lower spring member, and a pointer member;

said upper spring member being connected between said first portion of said indicating element and said pointer member;

said upper spring member having a first free length and a first spring constant;

said pointer member being connected between said upper spring member and said lower spring member and defining an indicating level;

said lower spring member being connected between said pointer member and said second portion of said indicating element;

said lower spring member having a second free length and a second spring constant;

said first and second free lengths and said first and second spring constants adapted to position said pointer member adjacent said sensing element;

wherein, upon movement of said first portion of said indicator member relative to said second portion of said indicator member, the position of said pointer member changes relative to said sensing element in proportion to movement of said first surface relative to said second surface.