WO1998015726A1

WO1998015726A1 - Method and control of regulation of vehicle cooling circuit by means of a thermally regulated water pump

Info

Publication number: WO1998015726A1
Application number: PCT/EP1997/005545
Authority: WO
Inventors: Peter Edelmann; Klaus Vogelsang; Peter Rose; Peter Heilinger
Original assignee: Voith Turbo Gmbh & Co. Kg
Priority date: 1996-10-09
Filing date: 1997-10-08
Publication date: 1998-04-16
Also published as: DE59709520D1; DE19641558A1; EP0931208B1; EP0931208A1

Abstract

The invention relates to a method of adjusting engine temperature by means of a cooling circuit comprising a coolant and a coolant pump. The invention is characterized by the fact that the temperature of the coolant is adjusted by means of at least one speed regulated coolant pump (7) dependent on engine temperature so that a predetermined maximum engine temperature value is not exceeded.

Description

Method and control for regulating the cooling circuit of a vehicle by means of a thermally controlled water pump

The invention relates to a method for adjusting the engine temperature by means of a cooling circuit and a device for adjusting the engine temperature.

Today, cooling circuits comprising a coolant, preferably water with the appropriate antifreeze additives, are generally used for cooling engines, in particular internal combustion engines. A certain amount of coolant flows through the engine to be cooled per unit of time, absorbs the heat to be dissipated from the internal combustion engine and transports it to a cooler, for example a finned cooler, in which the absorbed and transported amount of heat is released to the environment. The cooling capacity of such a system is essentially determined by the amount of coolant circulated. The coolant is circulated by means of a coolant pump. The flow rate of the coolant pump determines the coolant flow through the cooling circuit.

As is well known from the prior art, the delivery rate of the coolant pump is generally dependent on its speed. Conventional coolant pumps are in constant drive connection with the engine, so they work depending on the engine speed. A disadvantage of this method for cooling an engine, in particular an internal combustion engine, is that a high pump output is made available even in cases in which it is not required. For example, in summer and winter in such an arrangement, the same amount of coolant is always pumped through the cooling circuit. This leads to an unnecessary power consumption on the part of the engine, which in certain operating situations leads to unnecessarily high fuel consumption. This problem becomes particularly serious when a retarder is introduced into the cooling circuit, the working medium of which is also the cooling medium for the engine. Then, for safe heat dissipation, the flow rate of the coolant pump must be designed so that the heat can be dissipated even when the retarder is switched on. This requires pumps with very high performance.

It is therefore an object of the invention to provide a method for cooling engines, in particular internal combustion engines, with which the disadvantages of the prior art described above can be overcome, and a control device therefor.

According to the invention, this object is achieved by a method according to claim 1 and a device according to claim 17.

According to the inventive method for adjusting the engine temperature, it is provided that the coolant temperature in the cooling circuit is adjusted by means of a speed-controlled coolant pump such that an optimal engine temperature value is reached as quickly as possible and a maximum value is never exceeded.

In a further development of the invention it can be provided that the engine temperature is determined continuously, for example in sampling intervals which can be in a range from several seconds to milliseconds.

Instead of a fixed maximum temperature value for the motor, this value can be specified in a further development depending on the current engine power. In this way it is possible to keep the cooling circuit always close to the temperature limit of the engine drive, which is particularly fuel-efficient, since the performance of the coolant pump is then optimally adjusted.

It is particularly advantageous to use the method according to the invention in cooling circuits which comprise a retarder, which retarder can either be operated with a separate working medium, and the coolant is used only for heat exchange or, in a further developed embodiment, the coolant is the working medium of the retarder itself is.

In a further development of the invention it is provided that the retarder in the cooling circuit can be switched on and off, for example by means of a changeover valve which bypasses the coolant past the retarder when it is not working.

A particularly fuel-efficient embodiment provides that at least one further coolant pump is provided in addition to the speed-controlled coolant pump. This can either be engine speed dependent, vehicle speed dependent or retarder speed dependent.

In the case of a coolant circuit which comprises a plurality of coolant pumps, the speed-controlled coolant pump can be designed such that it provides the basic cooling load in the cooling circuit and the further coolant pump is only switched on under special loads, for example at

Ascent. In particular, such an arrangement proves to be particularly advantageous in cooling circuits which include a retarder. It can be provided here that the speed-controlled coolant pump is designed in such a capacity that it is suitable for every operating situation of the engine when it is not in operation or switched off retarder ensures sufficient cooling of the motor.

In a further development of this idea, it can then be provided that the at least one further coolant pump is switched on when the retarder is operated, so that the heat additionally generated in the retarder can still be dissipated safely, ie. H. with the help of this further coolant pump in combination with the speed-controlled coolant pump, sufficient cooling of the engine is ensured.

Of course, in an alternative embodiment of the invention it is also possible that the further coolant pump, which is operated as a function of the engine speed, retarder speed or vehicle speed, is dimensioned in such a way that it provides the basic power required for sufficient cooling of the engine in all

Provides operating states. The speed-controlled coolant pump is then operated only when the retarder is switched on, in such a way that the maximum engine temperature mentioned above is not exceeded on the engine. Water with the appropriate antifreeze is generally used as the coolant.

The retarder can be a primary retarder, ie a retarder whose speed is dependent on the engine speed, or a secondary retarder whose speed is dependent on the driving speed. Of course, it is possible that the coolant also serves as the working medium of the retarder. However, the invention is also intended to include the case that the coolant of the engine is not also the working medium of the retarder, but is merely passed, for example, through a heat exchanger and from there absorbs the heat which is generated in the retarder during braking operation. In addition to the method, the invention provides a device for adjusting the engine temperature.

The device according to the invention comprises means for determining the engine temperature, for example a temperature sensor which is usually attached in the vicinity of the engine or on the engine itself. Furthermore, the device comprises a cooling circuit with a coolant and a coolant pump for setting the engine temperature and a control device for regulating the delivery rate of the coolant pump or coolant pumps depending on the determined engine temperature.

In a particularly preferred embodiment, at least one of the coolant pumps is a speed-controlled coolant pump, i. H. such a delivery rate depends on the speed.

In one development of the invention, the cooling circuit of the device according to the invention comprises a retarder and a changeover valve.

It is particularly advantageous if, in the case of such a device with a retarder and a changeover valve, the device also has one

Has switching valve control.

It is particularly preferred if further pumps are provided in the coolant circuit to provide them with a separate control, for example for starting up and putting out of operation.

The invention will now be described by way of example with reference to the drawings.

Show it: Fig. 1 shows a drive unit with the regulating device according to the invention. Fig. 2 shows a drive unit with the control device according to the invention and a further coolant pump.

3 shows an alternative embodiment of the invention according to FIG. 2.

FIG. 1 shows a drive unit consisting of a motor 1 and a cooling circuit 3. The cooling circuit 3 comprises a cooler 5, a coolant pump 7, which is designed as a speed-controlled coolant pump, and an expansion tank 9, which always ensures sufficient overpressure on the pump suction side. Furthermore, one is in the cooling circuit

Switch valve 11 and a retarder 13 are provided. However, the invention is in no way limited to only those embodiments in which a retarder is arranged in the coolant circuit. The invention is also applicable if only engine cooling by means of a cooling circuit and a speed-controlled coolant pump is provided.

A bypass line 40 leads past the cooler and branches at point 42. A changeover valve 44 is arranged at point 42 and can be designed as a 3/2-way valve. The 3/2-way valve has the function of controlling the coolant flow in such a way that it can be led past the cooler either through the cooler or through the bypass line 40. In an operating phase with high heat dissipation, the 3/2-way valve controls the cooling flow partially or largely to the radiator 5. In the phase of low heat dissipation, the 3/2-way switchover valve 44 controls the coolant via the bypass line to the motor 1 or to the pump 7. The 3/2-way valve can be designed as an expansion control valve or as an electrical or pneumatic continuously regulating valve.

The cooler can be supported by a fan 15. In the present case, the engine 1 has a means for determining the temperature

Temperature sensor 20 on. Of course, several can Temperature sensors are positioned at various points in the engine or in the coolant line leading away from the engine. A temperature signal, which represents the current engine temperature, is fed to a control device 24 via the signal line 22. Of course, it is possible, for example, in the case of a plurality of temperature sensors, to supply the control device 24 with a multiplicity of temperature signals and to determine the actual temperature value, which serves as a reference variable in the present control circuit, by averaging over a multiplicity of temperature signals. In the control device 24 itself, a maximum temperature value for the motor is the target value for the

Control loop filed. It is possible that this maximum temperature setpoint is a single value for all operating states of the engine. Likewise, a value that follows the load state of the motor can directly affect the pump speed control, i.e. pump control is not only dependent on the temperature setpoint. The detection of the load status can

Torque sensor or the control unit of the engine. Various control algorithms are now conceivable. The speed-controlled coolant pump 7 can thus be operated at a certain constant speed and the control only intervenes when the engine temperature exceeds the predetermined maximum temperature value.

It is then adjusted, i. H. the delivery rate increases.

In a further development of the invention it can be provided that the amount of coolant that is conveyed by the engine is always measured by means of the speed-controlled pump so that the engine is run at the maximum permissible coolant temperature, i. H. The speed of the coolant pump is regulated by means of the control device 24 both in the event of deviations from higher and lower temperatures than the predetermined target temperature. In this way it is ensured that in the cooling circuit only the exact amount circulated to

Reaching the engine setpoint temperature is required. This is it Particularly advantageous if the coolant pump 7 is speed-controlled, which means that its delivery rate depends directly on the speed at which it rotates.

Arranged on the water circuit as shown in FIG

Control device according to the invention, which works with the method according to the invention, ensures that the delivery rate in both bypass operation, ie. H. if the coolant liquid is bypassed by the changeover valve 11 in the bypass 26 past the retarder 13, as is also sufficient in the case of the activation of the retarder 13, in order to provide sufficient engine cooling capacity. As an advantage over the coolant pumps used up to now, however, a considerable saving potential can be used, since when the retarder is switched off, the delivery rate of the water pump 7 turns out to be significantly lower, as a result of which fuel savings can be achieved.

2 shows a further embodiment of the invention, a further pump 30 being provided in the cooling circuit in addition to the speed-controlled pump 7. In this embodiment, the pump 30 is arranged upstream of the switching valve 11 for the bypass 26. For the same units as in Fig. 1, the same reference numerals are again chosen in Fig. 2.

The advantage of the design according to FIG. 2 can be seen in the fact that the speed-controlled pump 7, which is regulated by the control device 24 as a function of the motor temperature recorded by the sensor 20, can be designed to be very small in terms of its delivery rate, since a further one is present in the cooling circuit Pump 30 is provided, which in the present exemplary embodiment is operated as a function of the travel speed and ensures a basic delivery rate in the cooling circuit. The pump 30 is dimensioned such that when the retarder is not operated, that is to say in the state in which the coolant has passed the bypass line 26 past the retarder is sufficient to provide the pump power required for engine cooling. If coolant is now passed through the retarder 13 as the working medium and this is further loaded with heat by the retarder in operation, the delivery rate of the pump 30 is no longer sufficient to maintain the maximum permissible engine temperature. In this case, the control will respond and the control device will put the speed-controlled pump 7 into operation, which will then be operated at precisely such a speed that an additional delivery quantity is made available in order to prevent an inadmissible heating of the motor. The control device in turn works as described in FIG. 1, ie in the event of deviations from a predetermined engine temperature setpoint, the speed of the pump 7 is adjusted accordingly until this predetermined setpoint engine temperature is reached. As mentioned above, the control allows the coolant circuit to always run just so that the engine is close to the maximum permissible temperature. As already shown above, this results in considerable fuel savings.

In a third embodiment shown in FIG. 3, the same reference numbers as in FIGS. 1 and 2 are again used for the same units. Now the further pump 30 is arranged behind the changeover valve 11 immediately before the retarder 13. The basic load for the coolant delivery is now taken over by the speed-controlled pump 7. It is in turn controlled as a function of the engine temperature by means of the control device 24 in such a way that the speed-controlled pump is controlled as a function of the specified setpoint and the deviation of the actual value. The speed-controlled pump can be designed to be very low in terms of its delivery rate, since it only has to remove the heat generated in the coolant circuit without the retarder being switched on. If the retarder is now switched on, the further pump 30 is also switched on and the higher pump required for cooling Delivery volume made available by this. In contrast to the embodiment according to FIG. 2, in this embodiment the additional coolant quantity, which is used to reduce the heat load which arises from the activation of the retarder, is conveyed by the further coolant pump 30.

Both according to the embodiment according to FIG. 2 and also according to FIG. 3, the control device can additionally be connected to the changeover valve 11 via a signal line 32 in order to receive a status signal, which provides information as to whether the coolant is flowing through the

Retarder or bypassed by this. In the embodiment according to FIG. 2, it is then possible, for example, to activate the control by means of the control device 24 only when a status signal is present on the signal line 32, which indicates that the coolant is passed through the retarder and is used there as the working medium.

The drive of the speed-controlled pumps 7 can be operated by means of an electric motor, which in turn is connected to the electrical circuit of the vehicle. The control of the electric motors that are suitable for this purpose, for example, are known to the person skilled in the art from the prior art, see for example "Dubbel, Taschenbuch für den Maschinenbau, 18th edition, 1995, pages V18-V51.

Of course, in addition to the exemplary embodiment with the two coolant pumps shown, a plurality of coolant pumps can be provided, one or more of which are speed-controlled coolant pumps.

Claims

claims

1. A method for adjusting the engine temperature by means of a cooling circuit comprising a coolant and a coolant pump, characterized in that 1.1 the temperature of the coolant is adjusted by means of at least one speed-controlled coolant pump (7) as a function of the engine temperature in such a way that a predetermined maximum engine temperature value is not exceeded becomes.

2. The method according to claim 1, characterized in that the engine temperature is continuously determined.

3. The method according to claim 1 or 2, characterized in that the predetermined maximum temperature value is constantly adapted to the current engine power.

4. The method according to any one of claims 1 to 3, characterized in that the coolant circuit further one

Retarder includes, the working medium is the cooling medium.

5. The method according to claim 4, characterized in that the retarder can be switched on and off.

Method according to one of claims 1 to 5, characterized in that the coolant circuit comprises at least one further coolant pump (30) in addition to the at least one speed-controlled coolant pump (7).

7. The method according to claim 6, characterized in that the at least one further coolant pump (30) is operated depending on the engine speed.

8. The method according to claim 6, characterized in that the at least one further coolant pump (30) is operated depending on the vehicle speed.

9. The method according to claim 6, characterized in that the at least one further coolant pump (30) is operated depending on the retarder speed.

10. The method according to any one of claims 4 to 9, characterized in that the speed-controlled coolant pump (7) is designed in its performance such that it ensures adequate cooling of the engine when the retarder is switched off.

11. The method according to any one of claims 6 to 10, characterized in that the at least one further coolant pump (30) is switched on with the retarder switched on, so that sufficient cooling of the engine is ensured in this state.

12. The method according to any one of claims 6 to 10, characterized in that the speed-controlled coolant pump (7) is operated only when the retarder is switched on.

13. The method according to claim 12, characterized in that the at least one further coolant pump (30) is continuously operated and its performance is such that it ensures adequate cooling of the engine.

14. The method according to any one of claims 1 to 13, characterized in that the cooling medium water bw. is a mixture of water.

15. The method according to any one of claims 4 to 14, characterized in that the retarder (13) is a primary retarder.

16. The method according to any one of claims 4 to 14, characterized in that the retarder (13) is a secondary retarder.

17. Device for setting the engine temperature with 17.1 center for determining the engine temperature;

17.2 a cooling circuit with at least one coolant pump for setting the engine temperature;

17.3 a control device for regulating the delivery rate of the at least one coolant pump as a function of that by means of the means for determining the engine temperature.

18. The apparatus according to claim 17, characterized in that the at least one coolant pump comprises at least one speed-controlled coolant pump, the delivery rate depends on the speed.

19. Device according to one of claims 17 to 18, characterized in that the cooling circuit further comprises a retarder (13) and a changeover valve (11).

20. Device according to one of claims 17 to 19, characterized in that the device further comprises a changeover valve control device.

21. Device according to one of claims 17 to 20, characterized in that the device further comprises a control device for at least one further pump.

22. Device according to one of claims 17 to 21, characterized in that the cooling circuit comprises a bypass line which leads past the cooler.