Systems and methods for purging an exhaust reductant delivery system

Patent metadata

Field	Value
Publication number	US-10677231-B2
Application number	US-201615555052-A
Country	US
Kind code	B2
Filing date	Mar 3, 2016
Priority date	Mar 6, 2015
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

A hydraulic system comprises a fluid tank and a pump, including a pump reservoir, fluidly coupled to the tank via a supply line. A valve is in fluidic communication with the pump reservoir via a pressure line. A backflow line fluidly couples the pump reservoir to the fluid tank via a timer reservoir and an orifice included in the timer reservoir. The hydraulic system transitions between a normal state and a purge state. In the normal state in which the pump is on, a first portion of the fluid is communicated from the pump reservoir to the valve and a second portion of the fluid is communicated from the pump reservoir to the tank. In the purge state, the pressure line and valve are purged followed by the backflow line and the pump reservoir such that no fluid remains in the pump reservoir.

First claim

What is claimed is:

1. A hydraulic system, comprising:
a pump;
a pump reservoir;
a supply line fluidly coupling a fluid tank to the pump, the supply line structured to receive a fluid from the fluid tank;
a valve in fluidic communication with the pump reservoir;
a pressure line fluidly coupling the pump reservoir to the valve;
a timer reservoir including an orifice;
a backflow line configured to fluidly couple the pump reservoir to the fluid tank via the timer reservoir and
a controller configured to control operation of the hydraulic system so as to allow the hydraulic system to transition between a normal state and a purge state, wherein,
in the normal state:
the pump is on, a first portion of the fluid from the fluid tank is communicated from the pump reservoir to the valve via the pressure line, and a second portion of the fluid is communicated from the pump reservoir to the fluid tank through the backflow line via the orifice and the timer reservoir, and wherein, in the purge state:
a first negative pressure develops at an outlet of the pump, the first negative pressure creating a second negative pressure in the pump reservoir, the valve and the pressure line, the second negative pressure purging the valve and purging the pressure line in a first time period from pump shutdown, and
a third negative pressure develops in the backflow line, the third negative pressure drawing the fluid from the backflow line via the timer reservoir and the orifice into the pump reservoir, the third negative pressure further drawing air from the fluid tank into the pump reservoir such that the backflow line is purged in a second time period from pump shutdown, the second time period greater than the first time period, the first negative pressure continuing to draw the fluid to the fluid tank and purge the pump reservoir with the air for a third time period after the backflow line is purged, the purging of the pump reservoir venting the valve, the pressure line and the pump reservoir to atmospheric pressure such that no fluid remains in the pump reservoir.

2. The hydraulic system of claim 1 , wherein at least one of the timer reservoir, the orifice and the backflow line are structured to cause the second time period to be greater than the first time period.

3. The hydraulic system of claim 2 , wherein the timer reservoir is configured to contain a volume of the fluid to allow the backflow line to be purged in the second time period.

4. The hydraulic system of claim 3 , wherein the orifice has a diameter configured to allow the backflow line to be purged in the second time period.

5. The hydraulic system of claim 3 , wherein the orifice does not include a check valve such that the orifice allows bi-directional flow of the fluid between the pump reservoir and the fluid tank.

6. The hydraulic system of claim 1 , wherein the fluid is an exhaust reductant.

7. The hydraulic system of claim 1 , wherein the fluid comprises a diesel exhaust fluid.

8. The hydraulic system of claim 2 , wherein the pressure line has a first length and the backflow line has a second length longer than the first length, the second length configured to allow the backflow line to be purged in the second time period.

9. The hydraulic system of claim 8 , wherein a ratio between a backflow line volume of the backflow line and a pressure line volume of the pressure line is in a range of 30% to 35% inclusive.

10. An apparatus for purging a hydraulic system comprising a fluid tank containing a fluid, a pump, a pump reservoir, a supply line fluidly coupling the fluid tank to the pump, a valve in fluidic communication with the pump reservoir, and a pressure line fluidly coupling the pump reservoir to the valve, the apparatus comprising:
a timer reservoir including an orifice;
a backflow line fluidly coupling the pump reservoir to the fluid tank via the timer reservoir and
a controller configured to control operation of the apparatus so as to allow the hydraulic system to transition between a normal state and a purge state,
wherein, in the normal state:
the pump is on, a first portion of the fluid is communicated from the pump reservoir to the valve via the pressure line, and a second portion of the fluid is communicated from the pump reservoir to the fluid tank through the backflow line via the orifice and the timer reservoir, and

wherein, in the purge state:
a first negative pressure develops at an outlet of the pump, the first negative pressure creating a second negative pressure in the pump reservoir, the valve and the pressure line, the second negative pressure purging the valve and purging the pressure line in a first time period from pump shutdown, and
a third negative pressure develops in the backflow line, the third negative pressure drawing the fluid from the backflow line via the timer reservoir and the orifice into the pump reservoir, the third negative pressure further drawing air from the fluid tank into the pump reservoir such that the backflow line is purged in a second time period from pump shutdown, the first negative pressure continuing to draw the fluid to the fluid tank and purge the pump reservoir with the air for a third time period after the backflow line is purged, the purging of the pump reservoir venting the valve, the pressure line and the pump reservoir to atmospheric pressure such that no fluid remains in the pump reservoir,
wherein at least one of the timer reservoir, the orifice and the backflow line are structured such that the second time period is greater than the first time period.

11. The apparatus of claim 10 , wherein the timer reservoir is configured to contain a volume of the fluid to allow the backflow line to be purged in the second time period.

12. The apparatus of claim 11 , wherein the orifice has a diameter configured to allow the backflow line to be purged in the second time period.

13. The apparatus of claim 11 , wherein the orifice does not include a check valve such that the orifice is allows bi-directional flow of the fluid between the pump reservoir and the fluid tank.

14. The apparatus of claim 10 , wherein the fluid is an exhaust reductant.

15. The apparatus of claim 10 , wherein the fluid comprises a diesel exhaust fluid.

16. The apparatus of claim 10 , wherein the pressure line has a first length and the backflow line has a second length longer than the first length, the second length configured to allow the backflow line to be purged in the second time period.

17. The apparatus of claim 16 , wherein a ratio between a backflow line volume of the backflow line and a pressure line volume of the pressure line is in a range of 30% to 35% inclusive.

18. The apparatus of claim 10 , wherein an end of the backflow line coupled to the fluid tank is located within the fluid tank so as to be positioned above a surface of the fluid contained within the fluid tank.

19. A method of purging a hydraulic system comprising a fluid tank, a pump, a pump reservoir, a supply line fluidly coupling the fluid tank to the pump, a valve in fluidic communication with the pump reservoir, a pressure line fluidly coupling the pump reservoir to the valve, a backflow line, a timer reservoir and an orifice, the method comprising:
activating the pump so as to operate the hydraulic system in a normal state, the pump reservoir fluidly coupled to the fluid tank through the timer reservoir and the orifice via the backflow line, wherein a first portion of the fluid is communicated from the pump reservoir to the valve via the pressure line, and wherein a second

Assignees

• Cummins Emission Solutions Inc

Inventors

• Young Richard D

Classifications

• F04B23/02 Primary

  having reservoirs · CPC title

• F04B49/08

  Regulating by delivery pressure · CPC title

• F01N2610/02

  the substance being ammonia or urea · CPC title

• F01N3/208 Primary

  Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent · CPC title

• F01N3/2066

  Selective catalytic reduction [SCR] · CPC title