Injection controller

Patent metadata

Field	Value
Publication number	US-10753256-B2
Application number	US-201916239693-A
Country	US
Kind code	B2
Filing date	Jan 4, 2019
Priority date	Jan 9, 2018
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

An injection controller that is applied to an exhaust purification system including an injector that is located in an exhaust passage of an internal combustion engine and injects to supply a reducing agent in a liquid state to a NOx purification catalyst purifying NOx in an exhaust gas, and a pump that pressurizes and pumps the reducing agent to the injector through a reducing-agent passage. The injection controller includes an acquisition unit configured to acquire a variation quantity of a rotational speed of the pump caused in response to an injection of the injector or a correlation value that is a value correlative to the variation quantity, as a rotational variation parameter, and a determination unit configured to determine whether an air mixing exists in the reducing-agent passage based on the rotational variation parameter.

First claim

What is claimed is:

1. An injection controller configured to be applied to an exhaust purification system that includes (a) an injector located in an exhaust passage of an internal combustion engine and injects to supply a reducing agent in a liquid state to a NOx purification catalyst purifying NOx in an exhaust gas, and (b) a pump that pressurizes and pumps the reducing agent to the injector through a reducing-agent passage, the injection controller comprising:
a memory; and
a processor operatively coupled to the memory, the memory and the processor configured to cause the injection controller to:
acquire a variation quantity of a rotational speed of the pump caused in response to an injection of the injector, or acquire a correlation value that includes a current value of an energization current flowing through the pump when the pump is energized and is correlative to the variation quantity, as a rotational variation parameter;
determine whether an air mixing exists in the reducing-agent passage based on the rotational variation parameter; and
control an air releasing quantity of an air releasing valve based on determining whether the air mixing exists in the reducing-agent passage.

2. The injection controller according to claim 1 , wherein the memory and the processor further causing the injection controller to:
set a threshold for determining the air mixing, according to an injection quantity of the injector per unit time; and
determine whether the air mixing exists in the reducing-agent passage, based on a comparison result between the acquired rotational variation parameter and the set threshold.

3. The injection controller according to claim 2 , wherein the exhaust purification system further includes a tank that stores the reducing agent, an air releasing passage that is connected with the reducing-agent passage and communicates with the tank, and the air releasing valve that is attached to the air releasing passage and opens and closes the air releasing passage, and
wherein the memory and the processor further causing the injection controller to:
variably control the air releasing quantity per unit time; and
control the air releasing quantity when determining that the air mixing existing in the reducing-agent passage to be greater than the air releasing quantity.

4. The injection controller according to claim 3 , wherein the memory and the processor further causing the injection controller to:
estimate an air mixing quantity in the reducing-agent passage based on the acquired rotational variation parameter when determining that the air mixing exists in the reducing-agent passage; and
set the air releasing quantity when determining that the air mixing exists in the reducing-agent passage, based on the estimated air mixing quantity.

5. The injection controller according to claim 2 , wherein the memory and the processor further causing the injection controller to:
set the injection quantity per unit time, in response to an operation state of the internal combustion engine, to be greater than a reference injection quantity that is predetermined, when the injection quantity per unit time is less than the reference injection quantity; and
set the threshold in response to the set injection quantity per unit time.

6. The injection controller according to claim 1 , wherein
the exhaust purification system further includes a pressure detection device configured to detect a pressure in the reducing-agent passage, and
wherein the memory and the processor further causing the injection controller to:
execute a feedback control of a drive of the pump to control the pressure of the reducing agent detected by the pressure detection device in the injection of the injector to be a target pressure that is predetermined; and
acquire the rotational variation parameter when the pressure in the reducing-agent passage is controlled to be the target pressure.

7. The injection controller according to claim 1 , wherein the processor and the memory further causing the injection controller to determine that the air mixing exists in the reducing-agent passage in response to the rotational variation parameter becoming greater than an upper threshold and then becoming less than a lower threshold.

Assignees

• Denso Corp

Inventors

• Takemoto Eiji
• Oshima Tomomi

Classifications

• F01N2610/1446

  Means for damping of pressure fluctuations in the delivery system, e.g. by puffer volumes or throttling · CPC title

• F01N2610/1473

  Overflow or return means for the substances, e.g. conduits or valves for the return path · CPC title

• F01N3/2066 Primary

  Selective catalytic reduction [SCR] · CPC title

• F01N9/00

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• F01N3/04

  using liquids · CPC title