EP1023535A1

EP1023535A1 - Engine heater for water cooled engines

Info

Publication number: EP1023535A1
Application number: EP98915089A
Authority: EP
Inventors: Lars-Göran ANDERSSON
Original assignee: LGA Innovation AB
Current assignee: LGA Innovation AB
Priority date: 1997-04-04
Filing date: 1998-04-01
Publication date: 2000-08-02
Also published as: WO1998045596A1; SE9800178D0

Abstract

An apparatus for heating liquid cooled engines, comprising an engine heater tube (8) adapted to be connected to a low level cooling water passageway (2) of an engine block (3), for instance between cut off ends of a hose (9) or a tube belonging to the cooling system of the engine, inside which engine heater tube (8) there is mounted an electric resistance heater element (10) formed as a sling and connected to an electric output, and through which cooling water is introduced in the engine block (3), and in which means (4, 5, 6, 7) are provided for connecting the engine heater element to an electric source of current, which is an accumulator battery (13) adapted to be charged by the engine itself, and in which the apparatus comprises a thermostat (4) which is connected to the battery (13) for disconnecting the supply of current to the engine heater element (10) when the cooling water adjacent said element (10) has reached a predetermined temperature, further a timer (6) for adjustably setting the start/stop position at certain predetermined periods of time and/or setting of a predetermined operation time, and a voltage guard (5) which is connected parallely to the timer (6) and the thermostat (4) for disconnecting the entire apparatus when the voltage over the battery poles is below a predetermined value.

Description

ENGINE HEATER FOR WATER COOLED ENGINES

The present invention relates to an electric heater for the cooling water of water cooled engines, in particular internal combustion engines, and the invention more particularly relates to an electric heater for an engine having a generator which charges an accumulator battery, and which heater, as the source of current, utilizes the very accumulator battery of the engine, and/or a supplementary battery, likewise charged by the engine.

It is known that cold starting of an internal combustion engine leads to high outlets of air pollution. It is also unhealthy to sit down in a completely cooled down motor car, especially since it can take many minutes until the engine has reached such operative temperature that the heat from the cooling water can be used for heating the car coupe. It is therefore a general wish that the cooling water of the engine can be heated to a certain lowest temperature, preferably to at least 30-45°C before the engine is started and is taken into operation.

PRIOR ART

Since long apparatuses are known for pre-heating the cooling water of an internal combustion engine in which electric heater slings are arranged in the cooling water system of the engine and in which said heater slings are connected to an external source of current, generally an output for mains current. Such an apparatus is shown in the US patent 4,208,570. Said types of apparatuses give a very good heating effect but are disadvantageous in that there is a need for supply of mains current. Therefore, such apparatus can generally only be used close to a house or a flat, at hired parking places having outputs of mains current, etc.

Surprisingly it has shown that it is possible to make use of the accumulator battery or batteries charged by the internal combustion engine itself as the source of current for a heater of the engine cooling water system. By providing a special coupling and connection of a supply equipment it is possible to foresee that the battery or batteries and not subjected to such high consumption of current that it becomes difficult to start the engine.

Already 70 years ago certain attempts were made to utilize the very battery of the car as a heater for the cooling water. An apparatus for this purpose is shown for instance in the US patent 1 ,745,231 from the year 1928. Said apparatus comprises a heater chamber having a heater sling mounted therein, and which heater chamber is mounted in direct connection to the cooling water pump which, in turn, is connected to the cooling radiator of the engine. Heater slings in the heater chamber are connected to an accumulator battery, which, according to the patent, has to be an external battery, not charged by the engine itself, in order not to make it impossible to start said internal combustion engine.

Obviously the said suggested apparatus has not met with any commercial success, probably for the reason:

- that the heater, each time it is to be used, has to be started and stopped by hand by pressing a switch button,

- that the heater consumes a large amount of current depending on the structure thereof including a separate heater chamber mounted in communication with the cooling water pump,

- since the output of said heater chamber is connected to the cooling water radiator of the engine,

- for the reason that the function of the apparatus makes it necessary to use an electric cooling water pump which has to circulate the entire mass of cooling water during the heating phase,

- that there is a risque that the heater completely discharges the battery if the heater is allowed to stand connected too long,

- that the apparatus, for the operation thereof, makes it necessary that the cooling water pump rotates and forces the cooling water both through the engine cooling radiator and through the entire engine block and back to the heater chamber of the preheating apparatus, - that the cooling water pump consumes a large amount of current,

- and that the apparatus is connected at a place of the cooling water system which is subjected to strong cooling, namely at the cooling radiator, and therefore that the heat which is finally capable of being used by the engine block is poor.

PROBLEM TO BE SOLVED

Therefore the object of the invention has been to solve the problem of providing an engine heater for water cooled engines, which heater solely utilizes the very accumulator battery charged by the engine itself and/or a supplementary battery for heating, in the first place, the cooling water existing in the engine block, which heater quickly and simply can be mounted in the cooling water system of the engine without the need of assistance of special service personnel, which is formed with means, like a time regulator, for providing a connection of the heater from a set time and for a predetermined period of time, and which is formed with means, like a voltage supervision means, which switches the entire heater system off if the voltage over the battery poles tends to decrease to such low level that there may be starting problems for the combustion engine.

It is to be understood that the engine heater, for which patent is applied, is useful for all types of engines issuing such heat that they are formed with cooling water system, not only internal combustion engines but also gas motors, steam turbine motors, electric motors, etc.

An important feature of the engine heater according to the invention is that is formed for being mounted at a low level place close to the engine block, preferably in a rubber hose connecting the lower end of the cooling radiator with the engine block. By connecting the heater at such place the heat from the electric heater sling will, in the first place, be transferred to and used in the engine block, and there will be an autocirculation in the engine block in that the hot cooling water moves upwards and around in the engine block. Therefore there is no need for a cooling water pump, and the heated cooling water must not pass through the cooling water radiator or even reach said radiator. What is important is that engine block is heated.

THE INVENTION

Thus, the invention relates to an apparatus for heating liquid (water) cooled engines, comprising an engine heater tube arranged for making it possible to connect same to a low level place of an engine block, for instance between cut apart ends of a hose or a tube being a part of the cooling system of the engine, and inside which engine heater tube there is mounted a sling formed by an electric resistance heater element, and through which heater tube cooling water is introduced in the engine block, and whereby there are means for connecting the heater element to a source of electric current. The invention is characterized in

- that the source of electric current for the engine heater element is an accumulator battery which is charged by the engine itself, - that the apparatus comprises a thermostat connected to the battery for disconnecting the supply of current to the heater element when the cooling water has reached a predetermined temperature measured at a place close to said heater element,

- that the apparatus comprises a timer for adjustably setting a start/stop action at certain predetermined periods of time and/or for setting a predetermined operation time, and

- that the apparatus comprises a voltage sensing means (guard) arranged to disconnect the entire apparatus in case the voltage over the battery poles becomes decreased to a predetermined lowest voltage level.

Preferably the thermostat, the timer and the voltage guard are included in an "electronic box" of a type known per se, and which box is, in turn, connected to a source of current.

It has shown that a preferred temperature of the cooling water in the engine block, for avoiding the disadvantages involved in cold staring of the engine, is about + 45°C, and therefore that the thermostat can be set to a fixed maximum temperature of +45°C. It has also shown preferable to set the voltage guard (sensing means) so as to disconnect the heater system if the voltage over the battery poles, for a 12 V battery, tends to decrease to under 1 1.5 V, of for a 24 V battery to under 23.5V.

TIMER FUNCTIONS

The apparatus can be formed for several different timer functions:

1. Setting the clock function of the timer [setting normal time];

2. Setting collect time [the time when the car is to be started and to move off]; 3. Checking collect time [verifying correctly set time];

4. Indicating and activating automatic functions [activating the electronics]; 5a. Direct start: manual activation of the heater element [at cold cooling liquid]; 5b. Direct start: manual activation of the element

[at heated cooling liquid the heater element is activated when the temperature is < +45°C]; 6. Supervising 1 : as soon as the ignition lock of the vehicle is connected the element is automatically disconnected; 7. Supervising 2: the element is automatically disconnected if the voltage sinks to less than 1 1.5 V (12 V system) and 23.5 V respectively (24 V system).

As mentioned above, and as will be described more closely in the following, it is possible to supplement the system by supplying an additional battery, for instance a battery having a capacity of at least 25 Ah, and a backup relay which is connected to the charge generator of the vehicle, so that also said additional battery becomes charged by the engine itself when running.

PRACTICAL TESTS

In a couple or practical embodiments of the invention, mounted as shown in figures 1 and 2 there were used a heater element having an effect of 150W and of 240 W, respectively, for a voltage of 12V and 24V, respectively. At an external temperature of between 0°C and -10°C there was reached an engine block temperature of about + 45°C in about 120 minutes for an 150W heater, and in about 60 minutes for a 240W heater. An accumulator battery for use in combination with a heater element of 150W preferably should have a capacity of at least 60 Ah, and a battery for a heater element of 240W preferably should have a capacity of at least 80 Ah. The thermostat can be set for different connection and disconnection temperatures, for instance a temperature, measured close to the heater sling of in the engine block of between + 15°C and +45°C. Likewise the temperature interval between connection and disconnection of the thermo element can be set as desired, for instance so that the heater becomes connected at a temperature of for instance + (15-25)°C and becomes disconnected at a temperature of for instance + (35-45)°C. If a desired operation temperature of for instance + 45°C is reached before the said heating time has come to an end the heater is disconnected, and concurrently therewith the timer is disconnected. The heating function is resumed when the engine temperature has decreased to about + (15-25)°C. Likewise the heater is started manually according to the above points 5a and 5b.

Considering the results which have been reached by the tests the timer is set so that a 150W heater provides an operation time of 120 minutes and a 240W heater provides an operation time of 60 minutes. The timer can be programmed for delay of 0 - 24 hours, and it is preferably formed so that the calculated time for starting the engine and driving off the car is set, whereby the timer automatically starts the heating function 120 minutes or 60 minutes, respectively, in advance of the set time. If the engine is started before the lapse of said set time the electronics automatically disconnected the entire heater apparatus.

USE OF THE HEATER SYSTEM

The electronic means is formed with a set of buttons mounted at the instrument panel of the car. The set of buttons comprises several buttons or setting wheels for the following settings: A. CONNECTION AND DISCONNECTION:

On/Off button, Time button, > button, indicator bulb is switched on when the engine heater is activated;

B. SETTING CLOCK:

1 ) press Time button and > button concurrently therewith for more than 3 seconds, hour figures flash, to be changed by means of

> button;

2) press Time button again, minute figures flash, to be changed by means of > button, after 3 seconds the display shows the set time;

C. SETTING COLLECT TIME: 1 ) press Time button for more than 3 seconds, hour figures flash, to be changed by means of > button 2) press Time button again, minute figures flash, to be changed by means of > button, after 3 seconds the display shows real time; D. CHECKING SET COLLECT TIME: press Time button, set collect time is shown, after 3 seconds real time is shown;

E. ACTIVATION OF COLLECT/STARTING TIME:

(activation of automatic function): press > button and On/Off button concurrently therewith; the activation is indicated in that dots between hour figures and minute figures flash; for disconnecting automatic function once again press > button and On/Off button; when the heater is operating this is indicated on the display; for 150W system time is counted down from 120 minutes to zero minute, for 240W system time is counted down from 60 minutes to zero minute; F. DIRECT STARTING: MANUAL ACTIVATION OF THE ENGINE HEATER: press On/Off button for direct starting, or for disconnecting the heater; the display indicates how many minutes that the heater has been operating; for 150 W system time is counted down from 120 minutes to zero minute, for 240 W system time is counted down from 60 minutes to zero minute;

G. SUPERVISING 1 : if the ignition lock of the engine is switched on during the operation time of the engine heater the heater is automatically switched off; switching off also can be made by pressing On/Off button;

H. SUPERVISING 2: if the battery voltage decreases to less than 1 1.5V or 23.5V, respectively, the entire system is automatically switched off; I. SUPERVISING 3: the thermostat switches the system off at a cooling water temperature of + 45°C irrespective what setting that has been chosen, even during set time; the system is switched on when the cooling water temperature has decreased to + 15°C.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Now the invention is to be described more in detail with reference to the accompanying drawings. In the drawings figure 1 diagrammatically shows an engine heater system according to the invention mounted in the cooling system of an engine block of a combustion engine. Figure 2 is an enlarged view of the encircled detail of figure 1. Figure 3 is an embodiment of a control display for the heater according to the invention, and figure 4 shows a charging circuit diagram for en accumulator battery by means of a current system comprising a "back-up unit" in an engine heater apparatus comprising a supplementary electric accumulator battery. The engine heater system according to the invention generally comprises an electric heater 1 adapted to be connected to a low level cooling water inlet 2 of the engine block of an engine which has to be cooled, like a combustion engine 3 as shown in figure 1 , a thermostat 4, a voltage guard (sensing means) 5, a timer 6 and a control display 7 preferably mounted on the vehicle instrument panel for the engine.

The heater 1 comprises a connection tube 8 of a heat resistant material, for instance of metal or a suitable plastic material, which is formed for being connected between cut off ends of a cooling water hose 9, for instance by means hose clamps (not shown), and which tube encloses a sling 10 of an electric resistance element which, with the ends 1 1 thereof, projects through the walls of the heater tube 8 and which by conduits 12 are connected to the electric control unit for the apparatus.

It is important that the heater tube 8 is mounted so close to the cooling water inlet 2 of the engine block that the largest part of the heat issued by the heater sling 10 is transferred to the cooling water in the engine block. To this end the heater sling 10 can extend out through the heater tube and into the cooling water column in the part of the cooling water hose 9 located closest to the engine block.

A thermostat 4 is also mounted inside the heater tube 8, and said thermostat is likewise electrically connected to the electric control unit. The thermostat 4 is preferably adjusted so as to provide connection of current at a cooling water temperature which is not less than + (15-20)°C and to provide disconnection of current at a cooling water temperature of about +45°C. This guarantees that the cooling water temperature at connected engine heater always provides for a temperature of at least + (15-45)°C. as mentioned above the engine heater system is disconnected when the engine is running and the engine normally provides an operation temperature of the cooling water of about 80-90°C.

The electric heater sling 10 gets its power from an accumulator battery of the engine, which battery can be the ordinary starting and current supply battery 13 of the engine, but alternatively it can be a supplementary battery (see figure 4) connected so at to be charged parallelly with the starting battery 13. For preventing the battery from becoming discharged so strongly by the electric resistance element 10 that starting problems may appear the apparatus comprises a voltage guard (sensing means) 5 which disconnects the entire engine heater system when the current over the battery poles has decreased, for a 12V battery to 1 1.5V and for a 24V system to 23.5V.

For setting the engine heater system there is a timer 6 having a control panel 7 connected thereto, which panel, for practical reasons, is mounted on or clbse to the engine, or on the instrument panel of the car, the bus, the gas turbine, etc. As seen from figure 3 the control panel 7 for the timer 6 has three adjustment buttons, namely On/Off button 15, Timer button 16 and an adjustment button > 17. The functions of said three adjustment buttons have been explained above in connection to section "Use of the heater system". Each button 15, 16, 17 has a function indicator bulb 18 for indicating whether or not the function is operating. Preferably the current switch for the thermostat 4, the voltage guard 5 and the timer 6, and also parallel connections from the battery 13 and the generator 14 are connected as an integral unit in an "electronic box" which is formed as a complete control unit for the engine heater system. Controlling is made by means of the control panel 7 at the instrument panel of the vehicle (the car, the boat, the electric motor, the gas turbine, etc.).

In many cases it may be preferred to form the engine heater system with a supplementary battery 19 adapted to be charged as soon as the battery 13 for the ordinary supply of current and for starting the engine is fully charged. An electric coupling circuit can have the appearance as shown in figure 4, from which is evident that the generator 14 of the engine, controlled by a generator relay 20 and supervised by a charge indicator bulb 21 , provides a charging of the ordinary battery 13, and in which the starting motor 22 can be connected over a starting contact 23 and a starting switch 24.

For providing a charging of the supplementary battery 19 there is "back- up" coupling 25 which is connected to the generator 14 and to the ordinary battery 13, and which, when the ordinary battery 13 is fully charged, switches the charging function over to the supplementary battery 19 over a voltage sensing means and a switch 26. Under normal operation conditions both the ordinary battery 13 and the supplementary battery 19 will be substantially fully charged, so that the engine heater system can be utilized as desired without the risque that there will appear any starting problems. Electric current to the engine heater can be supplied either from the supplementary battery 19 or both from the supplementary battery 19 and the ordinary battery 13. REFERENCE NUMERALS

1 heater 14 generator

2 cooling water inlet 15 On/Off button

3 combustion engine 16 Timer button

4 thermostat 17 > button

5 voltage guard (sensing means) 18 indicator bulb

6 timer 19 supplementary battery

7 control panel 20 generator relay

8 connection tube 21 charge indicator bulb

9 cooling water hose 22 starting motor 0 sling of resistance element 23 starting contact 1 end 24 starting switch 2 conduit 25 "back-up" coupling 3 ordinary battery 26 voltage sensor, switch

Claims

C L A I M S

1. An apparatus for heating liquid (water) cooled engines, comprising an engine heater tube (8) adapted to be connected to a low level part (2) of an engine block (3), for instance between cut off ends of a hose (9) or a tube belonging to the cooling system of the engine, inside which engine heater tube (8) there is mounted an electric resistance heater element (10) formed as a sling and connected to an electric output, and through which cooling water is introduced in the engine block (3), and in which means (4, 5, 6, 7) are provided for connecting the engine heater element to an electric source of current, characterized

- in that the source of current for the engine heater element is an accumulator battery (13; 13, 19) adapted to be charged by the engine itself,

- in that the apparatus comprises a thermostat (4) which is connected to the battery (13) for disconnecting the supply of current to the engine heater element (10) when the cooling water adjacent said element (10) has reached a predetermined temperature,

- in that the apparatus comprises a timer (6) for adjustably setting the start/stop position at certain predetermined periods of time and/or setting of a predetermined operation time, and

- in that the apparatus comprises a voltage guard (5) which is connected parallelly to the timer (6) and the thermostat (4) for disconnecting the entire apparatus when the voltage over the battery poles is lower than a predetermined value.

2. Apparatus according to claim 1 , characterized in that the thermostat

(4), the voltage guard (5) and the timer (6) are connected in a relay /electronic box comprising means for connecting and disconnecting, respectively, the current at predetermined cooling water temperatures and at predetermined times, for disconnecting the current to the engine heater sling (10) in the cooling water system when the cooling water has reached a predetermined temperature, and for disconnecting the entire system when the voltage over the battery poles has decreased to a level which is lower than a predetermined voltage.

3. Apparatus according to claim 2, characterized in that the ignition key of the engine is connected to the electronic box so that the current to the heater element is disconnected as soon as the inanition system is activated and the engine is started.

4. Apparatus according to any of claims 1 , 2 or 3, characterized in that the engine heater tube (5) is mounted close to the inlet (2) for the cooling liquid at the engine block, preferably in the inlet cooling water hose (9) for the engine block.

5. Apparatus according to any of the preceding claims, characterized in that it comprises a supplementary accumulator battery (19) adapted to be charged by the generator (14) of the engine itself, when said engine is running, over a back-up relay (25) and connected so that the current of the engine heater is primarily supplied from said supplementary battery (19) and only secondarily when the voltage over the poles of said supplementary battery is lower than 1 1.5 V for 12 V batteries and 23.5 V, respectively, for 24 V batteries.

6. Apparatus according to any of the preceding claims, characterized in that the electric heater sling (10) has an effect of about 150 W or about

240 W, and in that the timer (6) is formed so as to automatically disconnect the current after the lapse of 120 minutes for a heater sling of 150 W and after the lapse of 60 minutes for a heater sling of 240 W, whereby a temperature of at least + 15┬░C and not more than + 45┬░C has been reached in the cooling water in the engine block.

7. Apparatus according to any of the preceding claims, characterized in that the timer (6) has an over bridging function for manual activation of the engine heater, and by means of which the heater can be connected for a period of time of 60-120 minutes irrespective of the clock set time.

8. Apparatus according to any of the preceding claims, characterized in that the thermo element of the thermostat (4) is connected in the cooling water column adjacent the electric resistance heater element (10).