EP1404950B1

EP1404950B1 - Cooling system for a motor vehicle engine

Info

Publication number: EP1404950B1
Application number: EP02735601A
Authority: EP
Inventors: Ian Graham Pegg; Leslie Williams Routledge; Richard Durnford
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2001-07-05
Filing date: 2002-06-05
Publication date: 2004-11-24
Anticipated expiration: 2022-06-05
Also published as: GB0116433D0; EP1404950A1; GB0212842D0; GB2377253A; DE60202073D1; WO2003004840A1; DE60202073T2

Description

Field

This invention relates to cooling systems for internal combustion engines, particularly for motor vehicles.

Background of the Invention

A typical automobile engine cooling system includes an engine coolant jacket, a radiator, a fan for drawing air through the radiator, a circulatory pump for circulating the coolant from the engine through the radiator and return.

Such a system typically includes a thermostat which opens to allow the circulation of the coolant when the engine reaches a minimum desired operating temperature. The coolant flow is driven conventionally by a pump rotated by a belt driven by the crankshaft pulley and the flow rate is dependant upon engine speed.

In order to improve engine efficiency different means have been utilised to enable the engine to operate at as higher temperature as is possible. For example in US-A-4 744 335, the engine is provided with a servo controlled flow valve at its coolant outlet. US-A-5 975 031 discloses a cooling system having a pump with an electrically driven motor the speed of which is varied with engine temperature. The system in US-A-5 975 031 also includes a radiator by-pass duct and discloses the use of a control valve upstream of the pump to control the ratio of the flows of water entering the pump from both the by-pass duct and radiator. US-A-6 032 618 discloses a cooling system in which a control valve located upstream of the pump controls the flow of water through the system dependant upon signals received from an electronic control.

A motor vehicle internal combustion engine cooling system according to the preamble of claim 1 is disclosed in DE 4 033 261 A.

The present invention provides a means of controlling the engine cooling system which is suitable for engine driven coolant pumps.

Statements of Invention

According to the present invention there is provided a motor vehicle internal combustion engine cooling system comprising a pump having an inlet for receiving coolant from a radiator or other coolant circuit and outlet directing coolant to the engine, the outlet having a flow restricting valve therein operable to vary the output from the pump, characterized by a control module for processing the valve condition and a plurality of other engine and vehicle conditions to determine a required coolant flow rate, and for increasing or decreasing the flow through the valve accordingly.

The flow restricting valve in the outlet of the pump creates a restriction at the outlet which has advantages in that cavitation at the inlet is not made worse and any increase in pressure due to the restriction is seen only in the pump and not in the rest of the coolant system. Increasing the flow restriction at the outlet of an impeller type pump reduces its power consumption giving a direct reduction in fuel consumption.

The flow restricting valve may be provided with an actuator, preferably a vacuum operated actuator which operates from a vacuum source on the vehicle, e.g. a vacuum pump or the engine inlet manifold pressure. The flow restricting valve may also be provided with a sensor which monitors the control position of the valve.

The pump could be an electrically driven impeller pump, but is preferably a mechanically driven impeller pump having a pulley wheel fixed to the pump shaft and driven by a suitable means e.g. endless belt, chain etc., connected to a pulley wheel fixed to the engine crankshaft. The system drive losses as compared with an electrically driven pump are lower. With a typical electrically driven pump the vehicle alternator must be upgraded and system losses are such the power consumed to drive the coolant pump is about 120% higher than for the engine driven pump.

The pump may be a separate unit mounted on the engine or a pump which is incorporated with its impeller located in the engine coolant jacket.

The module may be connected to a plurality of sensors for monitoring the plurality of engine conditions, and preferably vehicle passenger compartment conditions.

Yet another aspect of the invention provides a method of controlling the flow of cooling fluid through the cooling system of an internal combustion engine according to claim 8.

The restricting valve may be located in the pump outlet or adjacent thereto.

Description of the Drawings

The invention will be described by way of example only and with reference to the accompanying drawings in which:

Fig. 1 is a schematic drawing of an vehicle engine with an external coolant pump,

Fig. 2 is a schematic drawing of a coolant pump used with the cooling system according to the present invention, and

Fig. 3 is a flow diagram of a control for the restricting valve in the pump of Fig. 2.

Detailed Description of the Invention

With reference to Fig. 1, there is shown an internal combustion engine 11 having a cooling jacket through which a liquid coolant, typically a water/glycol mix, is pumped. The coolant is pumped through the engine 11 by a pump 12 mounted externally of the engine and which is rotated by an endless belt 13 driven by a pulley 14 conventionally secured to the engine crankshaft. The coolant enters the pump inlet 15 from a radiator (see Fig. 3) and is pumped through pump outlet 16 into the engine 11 via conduit 17. The coolant exits the engine via a thermostatically. regulated control valve or valves 18.

With reference also to Fig. 2, the pump 12 is an impeller pump and the impeller shaft 21 is rotated by a pulley wheel 22 (see Fig. 1) driven by the belt 13 in a well known manner. The coolant flow from the pump passes through a volume flow regulating or restricting valve 23 which may be of any suitable type, for example a ball valve, or plate valve, which causes minimum flow restriction when fully open.

The valve 23 may be enclosed in a separate housing which is mounted to the pump outlet 16 to form a single assembly, but preferably the valve is housed within the pump outlet 16 forming a single unit.

The valve 23 is operated by an actuator 24 which again may be of any suitable type, for example hydraulic, electrical, or preferably a vacuum actuator which operate by a vacuum source on the vehicle. The actuator 24 is biased to a valve open condition so that the valve 23 restricts coolant flow only when the actuator is energised, and is open in the case of actuator failure. The valve condition is monitored by a sensor 25.

Now with reference to Fig. 3 there is shown a cooling system which includes the pump 12. The liquid coolant is pumped into the engine 11 and the heated coolant exits the engine through outlet 18 and passes to a radiator 31 and typically to a heat exchanger 32 for heating the vehicle passenger compartment. The coolant then returns to the engine 11 via the pump 12.

A cooling fan 33 is arranged to draw cooling air through the radiator 31.

The valve actuator 24 is operated by a valve control 34 which receives control signals from a cooling system control module 35. The control module 35 receives input signals from a plurality of different sources. The module 35 receives a valve condition signal from sensor 25 to complete the control loop for the restricting valve 23, but the actual valve condition will be determined in response to other engine condition signals and to parameters which my be programmed into an engine map.

The sensors may be divided into three types, vehicle parameter 36, power train parameters 37, and heating and cooling parameters 38.

The vehicle parameter sensors 36 may include torque demand sensor e.g. accelerator pedal position, gear, speed and ignition key status.

The power train sensors 37 may include sensors for engine air intake temperature, cylinder head metal body temperature, engine coolant outlet temperature, engine speed, engine air flow, and engine fuel demand.

The heating and cooling sensors may include ambient air temperature, ambient pressure, air conditioning, passenger compartment temperature settings and fan control settings, and radiator fan status.

The above lists of sensors are by way of example only

The control module. 35 processes the input signals from the various sensors and determined the optimum engine temperature in accordance with the pre-programmed engine map. The valve actuator 24 is then activated to increase or decrease the flow through the valve 23 dependant upon the relationship between the required engine metal temperature and actual engine metal temperature and/or coolant flow rate required.

Claims

A motor vehicle internal combustion engine cooling system comprising a pump (12) having an inlet (15) for receiving coolant from the cooling circuit and an outlet (16) directing coolant to the engine, the outlet (16) having a flow restricting valve (23) therein operable to vary the output from the pump (12), characterised by a control module (35) for processing the valve condition and a plurality of other engine and vehicle conditions to determine a required coolant flow rate, and for increasing or decreasing the flow through the valve accordingly.
A system as claimed in Claim 1, wherein the valve is operated by an actuator (24).
A system as claimed in Claim 2, wherein the actuator (24) is a vacuum operable actuator.
A system as claimed in any preceding claim, wherein the module receives a valve condition signal from a sensor (25).
A system as claimed in any preceding claim, wherein the pump (12) is an impeller pump.
A system as claimed in Claim 5, wherein the impeller pump (12) is driven by mechanical means (13, 14).
A system as claimed in Claim 6, having an impeller shaft (21) with a pulley wheel (22) thereon which in use is driven by drive means (13) connected to the vehicle engine crankshaft (14).
A method of controlling the flow of cooling fluid through the cooling system of an internal combustion engine (11) which includes a circulatory pump (12), the volume output of the pump being controlled by a flow restricting valve (23) located at the pump outlet (16), characterised in that the flow through the valve is increased or decreased in response to the valve condition and a plurality of other engine and vehicle conditions.
The method as claimed in Claim 8, wherein the flow through the valve is increased or decreased by a control module which processes signals from a valve condition sensor (25) and a plurality of other sensors (36,37,38).