GB2357141A

GB2357141A - Combined resonator and coolant store for an IC engine

Info

Publication number: GB2357141A
Application number: GB9929110A
Authority: GB
Inventors: Sylvain Merour
Original assignee: Draftex Industries Ltd
Current assignee: Laird Holdings Ltd
Priority date: 1999-12-09
Filing date: 1999-12-09
Publication date: 2001-06-13
Also published as: GB9929110D0

Abstract

A coolant store for an internal combustion engine comprises a flexible, fluid-tight container 16 for storing coolant and arranged to collapse to a relatively small volume when it is substantially empty of coolant. The flexible container 16 is housed in a generally rigid thermally insulated housing 14 having a coolant passage coupled to the flexible container 16 and for coupling the flexible container 16 to a cooling system of an internal combustion engine 2. The coolant store also has an air passage 18 which communicates with a cavity formed by the internal volume of the housing 14 which is not taken up by the flexible container 16. The air passage 18 may be adapted for coupling to the induction system of an internal combustion engine. The cavity may form a resonator operable to reduce noise in the induction system. The resonator may be a Helmholtz resonator.

Description

2357141 COMBINED RESONATOR AND COOLANT STORE This invention relates to a

coolant store for an internal combustion engine which may be used to permit faster elevation of the engine temperature when starting from cold and faster heater of the passenger compartment of the vehicle. The invention is also concerned with reducting the induction noise of the engine.

It is known to provide a reservoir for the storage of coolant in a liquid cooling system.

The stored coolant is reinjected into the cooling circuit when the vehicle is started. This type of apparatus increases the speed of warming of the combustion chamber walls, or wan-ning of the lubrication oil and of warming of the passenger compartment of the vehicle. This accelerated warming of the combustion engine produces a reduction in emissions of pollutants and fuel consumption. This type of apparatus is known for example from US-A-5884588, FR-A-2736687 and WO 96/25597.

It is also known to provide an attenuation chamber in the air inlet apparatus (or induction system) of an internal combustion engine in which air is drawn through a filter before entering the inlet manifold of the engine. For example, one or more attenuation chambers formed as Helmholtz resonators may be disposed in the air inlet conduit and operate to reduce noise caused by pressure pulses in the induction system.

EP-A2-0894970 shows a combined air cleaner and fluid reservoir. The fluid reservoir is used for containing windscreen washer fluid for example and the air cleaner is used to 2 filter air before it passes into the combustion chamber of an internal combustion engine.

In accordance with the invention there is provided a coolant store for an internal combustion engine comprising a flexible, fluid-tight container for storing coolant and arranged to collapse to a relatively small volume when it is substantially empty of coolant, the flexible container being housed in a generally rigid thermally insulative housing having a coolant passage coupled to the flexible container and for coupling to the cooling system of an internal combustion engine and an air passage which communicates with a cavity formed by the internal volume of the housing which is not taken up by the flexible container.

Combined resonators and coolant stores embodying the invention will now be described by way of example with reference to the drawings in which:

Figure I is a schematic block diagram of apparatus in accordance with the invention being used to store coolant; Figure 2 is a schematic block diagram of the apparatus of Figure 1 being used as a Helmholtz resonator; Figure 3 is an alternative embodiment showing the apparatus used to store coolant; 3 Figure 4 is a schematic block diagram of the apparatus of Figure 3 used as a Helmholtz resonator; Figure 5 is a schematic block diagram of a further alternative embodiment showing the apparatus being used to store coolant; Figure 6 is a schematic block diagram of the apparatus of Figure 5 being used as a Helmholtz resonator; Figure 7A is a schematic plan view of a cylindrical form of the apparatus; Figure 7B is a schematic plan view of a generally rectangular form of the apparatus; and Figure 8 is a further alternative embodiment of the invention showing a variable volume resonator.

Figure 1 shows part of the cooling and induction system of an internal combustion engine 2.

The induction system is shown schematically having an air filter 4, an induction manifold 6 and an air inlet 8. It will be appreciated that the induction system could also include components such as a turbo charger and turbo intercooler (not shown).

4 The vehicle cooling system including, for example, the vehicle heating/climate control and cooling radiator and its connections, are schematically indicated by the ellipse 10 and its connections to the engine 2.

A generally conventional (typically mechanically driven) water pump 12 is arranged to circulate coolant around the engine 2 and cooling system 10.

A generally rigid housing 14 contains a flexible storage membrane 16. Preferably, the membrane 16 has a bellows shape. The housing 14 is in fluid communication with the air inlet via conduit 18. Similarly, the membrane 16 is in fluid communication with the cooling system via valve 20 and conduit 22. The housing 14 may be mounted on the engine 2 or in the engine compartment of the vehicle.

In Figure 1, the membrane 16 is shown in an expanded state and filled with coolant.

Conversely, in Figure 2, the membrane 16 is shown in a compressed state substantially empty of coolant.

Coolant may be pumped into and out of the membrane 16 by means of a reversible electrical pump 24 and via valve 20 (which is electrically controllable). The valve 20 and pump 24 are controlled by a control unit 26.

A plate 28 rests (or may be fixed, for example, by glueing) on the upper surface of the membrane 16. The plate 28 contacts an upper limit switch 30 in its uppermost position as shown in Figure 1 and contacts a lower limit switch 32 in its lower position as shown in Figure 2. The outputs of the limit switches 30 and 32 are used as inputs for the control unit 26. The plate 28 is generally larger (in plan) than the membrane 16 and is preferably guided along the housing interior wall as described below in connection with Figure 7.

Preferably, the housing 14 and plate 28 are thermally insulated so that when the membrane 16 is filled with hot coolant as described below, the rate of cooling of the coolant is reduced.

The general operation is as follows. When the engine is turned off, the valve 20 is opened by the control unit 26 and the pump 24 is driven to pump coolant from the engine into the membrane. When the membrane is full (as indicated by the limit switch 30), the valve 20 is closed and the pump 24 stops. In this way, a quantity of hot coolant is stored in the insulated housing 14.

When a driver begins to start the engine, a signal is sent to the control unit 26 which causes it to open the valve 20 and activate the pump 24 to transfer the relatively hot coolant from the membrane 16 to the cooling circuit of the engine 2. Eventually, the membrane 16 reaches the position shown in Figure 2 in which the limit switch 32 causes the control unit 26 to close the valve 20 and to turn the pump 24 off. In this way, the temperature of the engine is rapidly increased which reduces fuel consumption and the 6 emission of pollutants. Furthermore, the passenger compartment is more rapidly heated.

When the driver again turns off the engine, the cycle is reversed and hot coolant is pumped back into the membrane 16 using the pump 24, until the position shown in Figure 1 is reached.

With particular reference to Figure 2, when the membrane 16 is its low position, the housing 14 forms a Helmholtz resonator for the induction system of the engine. This serves to reduce induction noise resulting from the standing waves generated by the pressure pulses present in the induction system of an internal combustion engine. In this way, the housing conveniently integrates a resonator which produces noise reduction and a coolant accumulator which produces an emissions reduction but without using additional space. Thus costs are saved relative to the separate provision of a coolant store and a resonator and furthermore, space is gained in the vehicle engine compartment.

The plate 28 as mentioned above, preferably isolates the membrane 16 from the upper part of the housing 14. This prevents thermal leakage into the upper part of the housing 14. Alternatively, the plate 28 may not provide thermal isolation for the membrane 16.

However, this is a less optimal solution since this typically necessitates a valve operable to close the conduit 18 in order to prevent thermal leakage via that conduit. By using a thermally isolating plate 28, the cost of such an additional valve is avoided.

7 It will be noted that since the membrane 16 is flexible (and collapses when it is empty) there is no need to bleed or purge the cooling circuit after each transfer of fluid between the engine 2 and the membrane 16. Of, course, bleeding of the membrane 16 may be necessary after the cooling system has been drained.

It will also be noted that as the membrane 16 moves towards the position shown in Figures 1 and 3, the cooling system 10 and/or the coolant channels in the engine 2 experience a reduction in pressure. Preferably, controlled quantities of air at atmospheric pressure are allowed to enter the cooling circuit of the engine 2 and/or the cooling system 10. This may be achieved for example, by dimensioning the mouth of the expansion bottle of the cooling system to incorporate pressure compensation means or alternatively to include an anti-return valve which opens into air situated in the upper part of the expansion bottle. This valve is arranged to open at a predetermined depression in the cooling system 10.

The dimensions of the resonator are chosen primarily to obtain suitable acoustic properties. The volume of the housing 14 is always taken up in part by the volume of the membrane 16 (even when it is fully collapsed). Thus the calculation of the volume of the resonator must take into account the fact that the effective volume of the resonator will be smaller than the total volume of the housing 14. On the other hand, the volume of the housing 14 is also determined by the quantity of coolant which is to be stored in the membrane 16. It will be noted, that some adjustment to the resonant characteristic of the 8 resonator may be achieved by adjusting the length and section of the conduit 18.

With reference to Figures 3 and 4, the housing 14 may also include an additional resonant chamber 34 coupled, for example, downstream of the air filter 8, to the induction system of the engine 2.

Figures 3 and 4 also show additional valves 36,38 which allow the hot coolant to be circulated around the engine before it is started, which may further reduce emissions compared to the embodiment of Figures 1 and 2.

During filling of the membrane 16, valves 20 and 38 are open and valve 36 is closed.

The electric water pump 24 operates to pump coolant into the membrane 16. During this operation, the mechanical water pump 12 is stopped.

is Once the membrane 16 is full and during storage of the coolant, the pump 24 does not operate and the valve 20 is closed.

Figure 3 shows the membrane 16 in a position in which it is storing hot coolant.

Before starting of the engine 2, valves 20 and 38 are opened and valve 36 is closed. The electric water pump 24 operates to pump liquid via conduit 40, from the membrane 16 towards the cooling system 10.

9 Figure 4 shows the membrane 16 completely empty and collapsed. When the membrane is in this position, the control means 26 closes valves 20 and 38 and opens valve 36.

Coolant may then be circulated through the engine and cooling system 10 using the pump 24. It will be noted that this circulation of stored, warm coolant (which serves to preheat the engine 2) occurs before the engine 2 has started.

After preheating of the engine 2, the electric pump 24 is stopped, valve 36 is closed and valve 38 is opened. The control unit 26 then permits starting of the engine. Subsequent coolant circulation is produced by the action of the mechanical pump 12.

This technique may also be used to preheat the passenger compartment of the vehicle by automatically controlling the ventilation system to blow hot air into the compartment during circulation of the hot coolant in the cooling system 10.

As an alternative to the above configuration, the pump 24 may be operated in parallel with pump 12 once the engine has started. This may be achieved by having valve 36 open during operation of the engine 2.

Furthermore, the mechanical pump 12 may be omitted altogether as shown in Figures 5 and 6. This allows the control unit 10 to vary the speed of circulation of the water (by varying the speed of the pump 24) according to parameters such as the speed of the vehicle, the ambient air temperature, the temperature of water leaving the engine, the speed of rotation of the fan, the thermostat position, the power and the operation of the engine.

Figure 7 shows two possibilities for the plan shape of the housing 14. It also shows slots 42 formed in the housing 14 which guide protrusions 44 formed in the plate 28. This ensures that the membrane 16 moves up and down within the housing 14 smoothly and without twisting.

Figure 8 shows a further variation of the housing 14 in which the upper plate 28 is driven on a threaded rod 46 by a motor 48. This allows the control means 10 to adjust the resonant frequency of the upper part of the housing 14 to adjust the quietening affect on the induction system of the engine. Further adjustments may be made by including a variable valve in the conduit 18 operable to vary flow in that conduit and which is under control of the control means 10.

Further adjustment of the resonant characteristic of the cavity 14 may be made for example by controlled filling of the bellows 16 with a gas such as air during operation of the engine 2.

The insulation of the housing 14 may be achieved by forming the housing with double walls and filling the cavity defined thereby, with for example, air. An alternative is to evacuate the cavity formed by the double walls.

The housing 14 may also include the air filter 4 and may form part of an encapsulation apparatus of the engine 2. Furthermore, one or more of the valves and/or pumps may be included in the structure forming the housing 14. In this way the invention may be easily fitted to the engine 2 and/or repaired by replacement.

The housing 14 may also incorporate electrical heating means for heating the stored coolant. These are preferably located at the entrance to the housing 14 adjacent the valve (on the housing side of the valve).

The control unit 10 may form part of an engine management unit and/or may control other components of the cooling system such as for example an electronic thermostat and/or a ventilation or climate control system for the passenger compartment of the vehicle.

Preferably the generally rigid housing 14 is formed from a thermally insulating plastics material. The plate 28 may also be made from the same material. The flexible membrane 16 may be made, for example, from rubber. It will be noted that although the term "membrane" has been used, this is not limiting and any flexible container which is suitably heat resistant and which is collapsible as fluid is drawn out of it, is suitable.

The membrane 16 may be dimensioned to store only part of the coolant present in the whole of the engine and cooling system 2 and 10. For example, the capacity of the 12 membrane 16 may be sufficient only to hold the coolant present in the heating circuit and the engine circuits but not the coolant present in the radiator circuits. Preferably additional valves are provided either side of the radiator to cohtrol flow of coolant during the storage phase. It will be noted that when the engine is cold, the thermostat is shut and therefore the coolant in the radiator does not circulate. This variant provides the abovementioned advantages of emissions reduction etc and allows a smaller coolant store to be used; thus saving further space.

It will be appreciated that several of the coolant stores may be provided to allow storage of various quantities of coolant (possibly being different coolant materials) at different temperatures. This is useful, for example, for a vehicle having several coolant circuits.

It will also be appreciated that the positions of the connections into the vehicle induction system and the cooling system, may be varied from those shown in the drawings. The preferred position for the connection to the cooling system is upstream of the water pump 12. This configuration makes pumping of the coolant easier because the pump 12 is usually at a low position in the car. Similarly, the conduit 18 may, for example, be formed downstream of the air filter 4.

13

Claims

1. A coolant store for an internal combustion engine comprising a flexible, fluid tight container for storing coolant and arranged to collapse to a relatively small volume when it is substantially empty of coolant, the flexible container being housed in a generally rigid thermally insulative housing having a coolant passage coupled to the flexible container and for coupling to the cooling system of an internal combustion engine and an air passage which communicates with a cavity formed by the internal volume of the housing which is not taken up by the flexible container.

2. A coolant store according to claim 1, including an integral electrically operable valve operable to permit and prevent coolant flow in the coolant passage.

3. A coolant store according to claim 1 or claim 2, including an integral water pump operable to pump coolant into and/or out of the flexible container.

4. A coolant store according to any preceding claim, wherein the air passage is adapted for coupling to the induction system of an internal combustion engine and wherein the said cavity forms a resonator operable to reduce noise in the induction system of the internal combustion engine.

5. A coolant store according to claim 4, wherein the resonator is a Helmholtz 14 resonator.

6. A coolant store according to any preceding claim including a movable generally rigid dividing member which divides the housing into a first volume containing the flexible container and a second volume forming the said cavity.

7. A coolant store according to claim 6 when depending from claim 4 or claim 5, wherein the dividing member is movable to alter the resonant characteristic of the resonator.

8. A cooling system for an internal combustion engine including the coolant store of any preceding claim and arranged to transfer hot coolant to the store when the engine is turned off and to transfer stored coolant to the engine and/or vehicle passenger compartment heating system, immediately prior to, during and/or immediately after starting the vehicle engine.

9. A coolant store constructed and arranged as described herein with reference to the drawings.