Autolift-resistant piston assembly for an unloader valve of an air compressor

Patent metadata

Field	Value
Publication number	US-9994207-B2
Application number	US-201514820655-A
Country	US
Kind code	B2
Filing date	Aug 7, 2015
Priority date	Aug 7, 2015
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

An autolift-resistant piston assembly is provided for an air compressor. The piston assembly comprises an unloader piston having an interior chamber. The piston assembly further comprises a first coil spring for biasing the unloader piston to a loaded position when the piston assembly is installed in the air compressor. The piston assembly also comprises an inner member disposed in the interior chamber of the unloader piston and including (i) a body portion, and (ii) a tapered end portion extending from the body portion and facing an unloader air passage of the air compressor when the piston assembly is installed in the air compressor.

First claim

What is claimed is:

1. An autolift-resistant piston assembly for an air compressor, the autolift-resistant piston assembly comprising:
an unloader piston having an interior chamber;
a first coil spring for biasing the unloader piston to a loaded position when the autolift-resistant piston assembly is installed in the air compressor; and
an inner member disposed in the interior chamber of the unloader piston and including (i) a body portion, and (ii) a tapered end portion extending from the body portion and facing an unloader air passage of the air compressor when the autolift-resistant piston assembly is installed in the air compressor; wherein the tapered end portion of the inner member comprises a curved surface having a concave face originating from a raised vertex.

2. The autolift-resistant piston assembly according to claim 1 , wherein the first coil spring is disposed between an inner circumferential surface of the unloader piston and an outer circumferential surface of the inner member.

3. The autolift-resistant piston assembly according to claim 1 , further comprising:
a snap ring disposed on an end portion of the inner member and for maintaining the first coil spring compressed between the snap ring and an inner circumferential lip surface of the unloader piston.

4. The autolift-resistant piston assembly according to claim 1 , further comprising:
a second coil spring separate from the first coil spring, wherein (i) the first coil spring is disposed between an inner circumferential surface of the unloader piston and an outer circumferential surface of the inner member, and (ii) the second coil spring is disposed on an outer circumferential surface of the unloader piston.

5. The autolift-resistant piston assembly according to claim 4 , further comprising:
a first snap ring disposed on an end portion of the inner member and for maintaining the first coil spring compressed between the first snap ring and an inner circumferential lip surface of the unloader piston; and
a second snap ring disposed on an end portion of the unloader piston and for maintaining the second coil spring compressed between the second snap ring and a cylinder head bearing surface of the air compressor.

6. An unloader valve apparatus for an air compressor, the unloader valve apparatus comprising:
an unloader piston having a longitudinal central axis and movable along the longitudinal central axis between a loaded position and an unloaded position;
an inner member extending into the unloader piston;
wherein the unloader piston is movable between the loaded position in which the unloader piston blocks an unloader air passage and the unloaded position in which the unloader piston is not blocking the unloader air passage, wherein the unloader air passage is in fluid communication with compressed air from the air compressor;
a first coil spring for biasing the unloader piston to the loaded position, wherein the first coil spring is separated from compressed air in the unloader air passage during a compression stroke of the air compressor; and
a second coil spring separate from the first coil spring and for biasing the unloader piston to the loaded position, wherein the second coil spring is separated from compressed air in the unloader air passage when the unloader piston is in the loaded position.

7. The unloader valve apparatus according to claim 6 , wherein (i) the first coil spring is disposed between an inner circumferential surface of the unloader piston and an outer circumferential surface of the inner member, and (ii) the second coil spring is disposed on an outer circumferential surface of the unloader piston.

8. The unloader valve apparatus according to claim 7 , further comprising:
a first snap ring disposed on an end portion of the inner member and for maintaining the first coil spring compressed between the first snap ring and an inner circumferential lip surface of the unloader piston; and
a second snap ring disposed on an end portion of the unloader piston and for maintaining the second coil spring compressed between the second snap ring and a cylinder head bearing surface of the air compressor.

9. The unloader valve apparatus according to claim 7 , wherein the inner member includes (i) a body portion, and (ii) a tapered end portion extending from the body portion and facing the unloader air passage.

10. A vehicle air compressor apparatus for a heavy vehicle air braking system, the vehicle air compressor apparatus comprising: a compressor crankcase assembly; a compressor cylinder head assembly disposed on the compressor crankcase assembly and co-operating with the compressor crankcase assembly to generate compressed air, wherein the compressor cylinder head assembly has (i) an air inlet port through which air can be received for compression within the compressor crankcase and compressor cylinder head assemblies, (ii) a discharge port through which compressed air can be delivered from the compressor cylinder head assembly, and (iii) an unloader air passage; and an unloader valve assembly connected internally of the compressor crankcase and compressor cylinder head assemblies and including: an unloader piston defining an interior chamber and defining at least in part a control air chamber; an inner member disposed in the interior chamber of the unloader piston; a first coil spring for biasing the unloader piston to a loaded position, wherein (i) the unloader piston moves from the loaded position against a biasing force of the first coil spring to an unloaded position when a governor control air pressure is applied to the control air chamber to unload the unloader piston and thereby vent compressed air from the unloader air passage to a location which is other than the heavy vehicle air braking system, and (ii) the unloader piston moves back from the unloaded position to the loaded position under the biasing force of the first coil spring when the governor control air pressure is removed from the control air chamber; wherein (i) the first coil spring is disposed between an inner circumferential surface of the unloader piston and an outer circumferential surface of the inner member, and (ii) the first coil spring is separated from compressed air in the unloader air passage during a compression stroke of the air compressor; and a second coil spring separate from the first coil spring and for biasing the unloader piston to the loaded position, wherein (i) the second coil spring is disposed on an outer circumferential surface of the unloader piston, and (ii) the second coil spring is separated from compressed air in the unloader air passage when the unloader piston is in the loaded position.

11. The vehicle air compressor apparatus according to claim 10 , wherein the inner member includes (i) a body portion, and (ii) a tapered end portion extending from the body portion and facing the unloader air passage.

Assignees

• Bendix Commercial Vehicle Systems Llc

Inventors

• Yeats Padraig B
• Geither Jeffrey M
• Harte Shane A

Classifications

• F04B39/1013

  the members being of the poppet valve type · CPC title

• F04B39/123

  Fluid connections · CPC title

• F04B39/10

  Adaptations or arrangements of distribution members · CPC title

• F04B49/03

  by means of valves · CPC title

• B60T17/02 Primary

  Arrangements of pumps or compressors, or control devices therefor · CPC title