Cooling system controller and method of controlling cooling system

• US 10,400,660 B2
• Filed: 02/20/2014
• Issued: 09/03/2019
• Est. Priority Date: 02/20/2014
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Nagai, Hiroyuki, Fukami, Toru
• Primary Examiner(s): Dounis, Laert
• Assistant Examiner(s): Stanek, Kelsey L
• Application Number:
  US15/112,705
• Publication Number:
  US 20160341100A1
• Time in Patent Office: 2,021 Days
• Field of Search: 60320
• CPC Class Codes: F01N 2410/00 By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other device
• CPC Class Codes: F01N 3/0205 using heat exchangers
• CPC Class Codes: F01N 5/02 the devices using heat
• CPC Class Codes: F01P 2007/146 using valves
• CPC Class Codes: F01P 2060/08 Cabin heater
• CPC Class Codes: F01P 2060/16 Outlet manifold
• CPC Class Codes: F01P 3/20 Cooling circuits not specific to a single part of engine or machine F01P3/22 takes precedence
• CPC Class Codes: F01P 5/10 Pumping liquid coolant; Arrangements of coolant pumps
• CPC Class Codes: F01P 7/16 by thermostatic control
• CPC Class Codes: F02M 26/22 with coolers in the recirculation passage
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A cooling system controller controls a cooling system at least having a coolant pump (3) configured to supply a coolant to an internal combustion engine, a heat radiator (9) configured to cool the coolant, and an exhaust heat recovery system (6) configured to perform in heat exchange between the exhaust gas and the coolant. In addition, the cooling system controller (12) has a unit configured to control the coolant flow rate, a unit (13) configured to obtain a coolant temperature or pressure of the internal coolant passage of the engine, and a unit configured to obtain an internal coolant temperature or pressure of the exhaust heat recovery system. Furthermore, the coolant flow rate is restricted at a cold start of the internal combustion engine, and the restriction of the coolant flow rate is released on the basis of the coolant temperature or pressure of the engine coolant passage and the internal coolant temperature or pressure of the exhaust heat recovery system.

Claims

1. A cooling system controller that controls a cooling system at least having a coolant pump configured to supply a coolant to an engine coolant passage provided in an internal combustion engine, a heat radiator configured to radiate heat from the coolant passing through the engine coolant passage to the external air to lower a temperature of the coolant, and an exhaust heat recovery system configured to perform heat exchange from an exhaust gas of the internal combustion engine to the coolant, the cooling system controller comprising:

a coolant passage that links the engine coolant passage and the heat radiator;

an exhaust heat recovery coolant passage that branches from the coolant passage at a point between an outlet port of the engine coolant passage and an inlet port of the heat radiator and joins to the coolant passage at a point between an outlet port of the heat radiator and an inlet port of the engine coolant passage, the exhaust heat recovery system being arranged in the exhaust heat recovery coolant passage;

a multi-flow control valve disposed at the point where the exhaust heat recovery coolant passage branches from the coolant passage and configured to select a coolant flow passage out of the coolant passage and the exhaust heat recovery coolant passage; and

a coolant flow rate control unit that controls a coolant flow rate flowing through the cooling system,

wherein the coolant flow rate control unit controls the coolant flow rate flowing through the cooling system by switching a coolant flow passage by using the multi-flow control valve, and

wherein, the exhaust heat recovery system is arranged in the exhaust heat recovery coolant passage at a point after the exhaust heat recovery coolant passage branches from the coolant passage.

2. The cooling system controller according to claim 1, wherein a restriction of the coolant flow rate is released at least when a variation of a coolant temperature or pressure of the engine coolant passage reaches an engine-side target value or when a variation of an internal coolant temperature or pressure of the exhaust heat recovery system reaches a flow rate restricting threshold.

3. The cooling system controller according to claim 2, wherein the flow rate restricting threshold is set to be lower when a heat exchanger such as an exhaust gas recirculation (EGR) cooler or an oil cooler is interposed in the coolant passage between the outlet port of the exhaust heat recovery system and the inlet port of the heat radiator, compared with a case when the heat exchanger is not interposed.

4. The cooling system controller according to claim 1, wherein an exhaust heat recovery system internal-condition obtaining unit configured to obtain an internal coolant temperature or pressure of the exhaust heat recovery system estimates the internal coolant temperature of the exhaust heat recovery system by using a variation of the internal coolant temperature of the exhaust heat recovery system obtained on the basis of an exhaust heat recovery amount recovered by the exhaust heat recovery system, a specific heat capacity of the coolant, and a mass of the internal coolant of the exhaust heat recovery system.

5. The cooling system controller according to claim 4, wherein, when the coolant flow rate is restricted, an exhaust heat recovery system internal-condition obtaining unit computes an exhaust heat recovery amount on the basis of an exhaust gas flow rate obtained from an engine rotation speed and an engine torque, an exhaust gas temperature of an inlet port of the exhaust heat recovery system obtained from the engine rotation speed, the engine torque, and an ambient temperature detected by an ambient temperature sensor at an engine start or a coolant temperature of the engine coolant passage at an engine start, and a previous internal coolant temperature of the exhaust heat recovery system.

6. The cooling system controller according to claim 4, wherein, when the coolant flow rate is not restricted, the exhaust heat recovery system internal-condition obtaining unit computes an exhaust heat recovery amount on the basis of the exhaust gas flow rate obtained from the engine rotation speed and the engine torque, the exhaust gas temperature of the inlet port of the exhaust heat recovery system obtained from the engine rotation speed, the engine torque, and an ambient temperature detected by an ambient temperature sensor at the engine start or a coolant temperature detected by a coolant temperature sensor at the engine start, the previous internal coolant temperature of the exhaust heat recovery system, and an internal coolant flow rate of the exhaust heat recovery system obtained from the engine rotation speed and a valve opening level of the multi-flow control valve.

7. The cooling system controller according to claim 1, wherein a restriction of the coolant flow rate is released when either a pressure variation of a coolant pressure of the engine coolant passage or a pressure variation of an internal coolant pressure of the exhaust heat recovery system reaches a pressure variation threshold.

8. The cooling system controller according to claim 1, wherein the cooling system further has a warming heater in the exhaust heat recovery coolant passage between the exhaust heat recovery system and the coolant pump.

9. A method of controlling a cooling system at least having a coolant pump configured to supply a coolant to an engine coolant passage provided in an internal combustion engine, a heat radiator configured to radiate heat from the coolant passing through the engine coolant passage to the external air to lower a temperature of the coolant, a coolant passage that links the engine coolant passage and the heat radiator, an exhaust heat recovery system, arranged in an exhaust heat recovery coolant passage that branches from the coolant passage at a point between an outlet port of the engine coolant passage and an inlet port of the heat radiator and joins to the coolant passage at a point between an outlet port of the heat radiator and an inlet port of the engine coolant passage, the exhaust heat recovery system arranged in the exhaust heat recovery coolant passage at a point after the exhaust heat recovery coolant passage branches from the coolant passage and configured to perform heat exchange from the exhaust gas of the internal combustion engine to the coolant, a coolant flow rate control unit configured to control a coolant flow rate flowing through the cooling system, and a multi-flow control valve disposed at the point where the exhaust heat recovery coolant passage branches from the coolant passage and configured to select a coolant flow passage out of the coolant passage and the exhaust heat recovery coolant passage,

wherein restriction of the coolant flow rate and releasing of the restriction of the coolant flow rate are performed by switching a coolant flow passage by using the multi-flow control valve.