Thermal pulse type heater for coolant systems and the like
BACKGROUND OF THE INVENTION 
     This invention relates to new and useful improvements in pre-heaters for the coolant of a liquid cooled automobile engine or the like. 
     The use of coolant heaters is widespread in areas experiencing relatively cold ambient temperatures particularly in the winter months and three types of heaters are currently available for incorporation in the cooling system of automobile engines. 
     Imersion heaters consist of an element which is inserted within the cooling system and heats the coolant when the element is connected to a source of electrical energy. 
     Tank type heaters are relatively small reservoirs inserted in series or parallel with the coolant system with a heater element within the reservoir to heat the coolant therein. Once again the heating element is connected to a source of electrical energy. 
     Thermal pulse-type heaters are used which include a pair of intermittently operating one-way valves and a heater element connected to a source of electrical energy whereby the pressure difference within the heater operates the valves intermittently. 
     The immersion heater is normally installed within the block of the engine whereas the other two types are installed into the lines of the cooling system. 
     All of these devices suffer from several disadvantages and the present invention overcomes disadvantages inherent with these heaters and provided a heater for coolant which is efficient, easy to install and which includes the necessary safety devices. 
     SUMMARY OF THE INVENTION 
     The principal object and essence of the invention is to provide a heater of the character herewithin described which consists of a one-way valve at the outlet end, a heating element connectable to a source of electrical energy, a reservoir, a fluid level control valve adjacent the inlet to the reservoir and which may incorporate an over temperature control device incorporated into the supply cord. 
     Another object of the invention is to provide a device of the character herewithin described which is easily installed within a coolant hose of the cooling engine of an automobile engine or the like. 
     Still another object of the invention is to provide a device of the character herewithin described which is simple in construction, economical in manufacture and otherwise well suited to the purpose for which it is designed. 
     With the foregoing objects in view, and other such objects and advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, my invention consists essentially in the arrangement and construction of parts all as hereinafter more particularly described, reference being had to the accompanying drawings in which: 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The drawing is a side sectional elevation of the device. 
    
    
     DETAILED DESCRIPTION 
     Proceeding therefore to describe the invention in detail, the device consists of a substantially cylindrical reservoir 10 which is preferably made in two portions normally secured together around the flanged joining surface 11, by means of bolts 12 or the like thus allowing assembly of the device during manufacture. 
     A conventional heating element 13 is situated within the reservoir 10 adjacent the lower side thereof and is connected to a source of electrical energy (not illustrated) by means of a line cord 14. This line cord incorporates a plug assembly 15 engageable within a cylindrical shroud 16 on one end of the reservoir and preferably incorporates an over temperature control device in the form of a thermostat 17 as clearly described in Canadian Patent No: 850,765, issued Sept. 1, 1970. 
     A cylindrical inlet connection 18 is situated at one end of the reservoir 10 and adjacent the upper side thereof, communicating with a valve seat 19 which in turn communicates with a vertically situated cylindrical shroud 20 carrying a fluid level control valve 21. The valve consists of a plastic ball valve element 22 movable freely within the shroud 20 and below the valve seat 19, and adapted to close off the inlet 18 when the ball engages with the valve seat 19 from the underside thereof. A pin 23 retains the ball valve element within the shroud. The valve seat is preferably formed at the base of a cylindrical portion or sleeve 19A which engages within a bore 20A and abuts against a shoulder 18A formed at the inner end of the inlet connection 18 and the shroud 20 may be formed integrally with the sleeve and extends at right angles therefrom. 
     The plastic ball element 22 is manufactured from a material having a specific gravity less than the specific gravity of the coolant normally used within an automobile engine so that under normal circumstances, the ball element floats in the coolant. This means that if the reservoir is full of coolant, the ball element is engaged against the seat 19 thus closing off the inlet 18. 
     An cylindrical outlet connection 24 is provided at the opposite end of the reservoir and communicates with a shroud 25 having a valve seat 26 at the lower side thereof. A one-way valve 27 consists of a plastic ball 28 movable freely within the shroud 25, upward movement being restricted by means of a pin 29 as clearly shown. When in the lowermost position shown in the drawing, the ball 28 engages the seat 26 and closes off the outlet 24. This shroud is preferably formed integrally with and at right angles to a cylindrical portion 26A which engages within a bore 25A and abuts against a shoulder 24A formed at the inner end of the outlet connection 24. 
     This ball is manufactured with a specific gravity greater than the specific gravity of the coolant so that normally it sinks if the reservoir is full of coolant thus closing off the outlet as shown due to the engagement of the ball 28 with the valve seat 26. 
     In its initial stage, and after proper installation in series with a coolant hose (not illustrated), it will be observed that both the inlet and outlet connections 18 and 24 are in the uppermost portion relative to the body of the reservoir with the element 13 adjacent the lower portion of the reservoir. The reservoir normally will be full of coolant due to the circulation of the coolant by the conventional pump and when the element is activated by connection of the line cord 14 to a source of electrical energy, the coolant inside the reservoir heats up and expands. The pressure generated causes the coolant to open the one-way valve 27 by lifting the ball 28 from the seat 26 so that some coolant flows through the outlet connection 24 due to expansion of the coolant. As the pressure in the whole system builds up, the coolant in the reservoir starts to boil and therefore vaporize and this causes the level of the liquid in the reservoir to fall. It will be observed that the valve seat 19 is spaced below the upper side 30 of the reservoir so that provided the level of coolant is above this valve seat, the ball 22 is in the uppermost position thus closing off the inlet. However, when the level of the coolant falls below the level of the valve seat 19 the ball 22 sinks with the coolant level so that, fresh coolant is allowed in causing the temperature in the reservoir to fall. This reduces the pressure and allows a further flow of coolant into the reservoir and when pressure equilibrium is obtained, both the outlet and inlet valves close so that the cycle repeats itself. It will of course be appreciated that with the reservoir full, the expansion of the coolant causes coolant to flow only through the outlet as the fluid control valve 21 acts as a back check valve thus preventing the back flow of coolant. 
     When the coolant in the entire system has been heated sufficiently, the incoming fluid will not cool the reservoir enough to permit further fluid to enter. This causes over heating in the reservoir and the over temperature control thermostat 17 will operate to shut off the element 13 until the reservoir cools down sufficiently. However, this will only occur in exceptional cases when the ambient temperature is relatively high. 
     Since various modifications can be made in my invention as hereinabove described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.