Engine cold start warmup method

Patent metadata

Field	Value
Publication number	US-9551313-B2
Application number	US-201214653625-A
Country	US
Kind code	B2
Filing date	Dec 19, 2012
Priority date	Dec 19, 2012
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

A cooling-water temperature is detected at startup of an engine. When the detected temperature falls below a set water-temperature, a water pump is stopped independently of a normal control on rotational frequency of the water pump depending on engine operational state. Calculated is a total heat amount required for raising the current water-temperature to the set water-temperature, and integrated is an heat amount lost by the cooling water from the engine from the startup. When an integrated value reaches the total heat amount, the water pump is operated for a required time to uniformize temperature distribution of the cooling water. Then, the cooling-water temperature is detected again. If the detected temperature is still below the set water-temperature, the same control is repeated; if the detected temperature is equal to or greater than the set water-temperature, the normal control is restored.

First claim

The invention claimed is:

1. A method for warming an engine at cold startup wherein a water pump controllable in flow rate is employed for a cooling water system of the engine, a rotational frequency of said water pump being controlled to circulate cooling water at a flow rate depending on an operational state of the engine, the method comprising detecting a water temperature of the cooling water at the startup of the engine; and, when the detected water temperature falls below a set water temperature, stopping the water pump independently of a normal control of controlling the rotational frequency of the water pump depending on the operational state of the engine and calculating a total heat amount required for raising a current water temperature to said set water temperature, integrating a heat amount lost by the cooling water from the engine since the startup of the engine, operating the water pump for a required time to uniformize temperature distribution of the cooling water upon attainment of an integrated value to said total heat amount, and then detecting the water temperature of the cooling water again, repeating the method when the detected water temperature is still below the set water temperature and restoring the normal control when the detected water temperature is the same or above the set water temperature.

2. The method for warming the engine at cold startup as claimed in claim 1 , wherein for calculation of the total heat amount required for raising the current water temperature to the set water temperature, the detected water temperature is subtracted from the set water temperature to obtain a difference, the difference being multiplied by a mass flow rate of the cooling water in the engine to obtain a product, the product being multiplied by a specific heat of the cooling water to thereby obtain said total heat amount.

3. The method for warming the engine at cold startup as claimed in claim 1 , wherein a control map is used which can read out a heat amount lost by the cooling water in view of various information indicative of an operational state of the engine, the heat amount lost by the cooling water being read out from said control map based on the basis of the various information on the current operational state of the engine.

4. The method for warming the engine at cold startup as claimed in claim 1 , wherein an amount of heat generation by fuel is calculated based on fuel injection amount, and a part thereof used for engine output and a part thereof heat-released to the exhaust are subtracted from said amount of heat generation by the fuel to obtain the heat amount lost by the cooling water.

5. The method for warming the engine at cold startup as claimed in claim 2 , further comprising: determining from a control map a heat amount lost by the cooling water in view of various information indicative of an operational state of the engine, the heat amount lost by the cooling water being read out from said control map based on operational state of the engine.

6. The method form warming the engine at cold startup as claimed in claim 2 , further comprising: calculating an amount of heat generation by fuel based on a fuel injection amount, and subtracting a part thereof used for engine output and a part thereof heat-released to the exhaust from said amount of heat generation by the fuel to obtain the heat amount lost by the cooling water.

Assignees

• Hino Motors Ltd

Inventors

• Ishimori Takashi

Classifications

• F01P2037/02

  starting · CPC title

• F01P7/162

  by cutting in and out of pumps · CPC title

• F02N2200/023

  Engine temperature · CPC title

• F02N19/001

  Arrangements thereof · CPC title

• F02N19/10 Primary

  by heating of engine coolants · CPC title