WATER-COOLED INTERNAL COMBUSTION ENGINE WITH INSULATED ACCUMULATOR TANK FOR STORAGE OF COOLANT

Abstract: Liquid-cooled internal combustion engine with a cooling system comprising an insulated accumulator tank for storage of heated coolant. With the aid of an electrically driven circulation pump, at start heated coolant can be supplied to the coolant channels of the engine via its ordinary coolant pump, at the same time as cold coolant from the engine block is fed via a controlled valve to the tank. A flow barrier in the tank in the form of a wound flow-optimized conduit prevents cold and warm coolant from being mixed.

Description: Water -cooled internal combustion engine with insulated accumulator tank for storage of coolant The present invention relates to a liquid-cooled internal combustion engine with an engine block provided with coolant channels and a coolant system communicating with the coolant channels, said coolant system comprising a radiator, a coolant pump, a thermostatic valve arranged in an inlet conduit from the engine block to the radiator, an accumulator tank containing a flow barrier and an inlet and an outlet, which communicate with the coolant channels in the engine block, and a circulation pump communicating with the coolant channels of the engine block and the accumulator tank. NO 150012, for example, reveals as previously known an internal combustion engine of this type, which has a system for storing warm coolant from an engine in an insulated accumulator tank. Prior to start, the warm accumulated coolant is fed to the coolant channels of the engine block or some other engine component to heat the engine. In order to make the construction as effective and compact as possible, it has been realized that one should not mix hot and cold coolant in the accumulator tank. One has not, however, been able to successfully solve the problem in practice, with a simple functional solution. One has also completely neglected the need to prevent, as much as possible, the mixture of cold and warm coolant in the engine block, when the engine block is to be heated before starting. The guiding and controlling of the coolant between the various units is also deficient. Two different types of accumulator tanks have been described. The first has a dividing wall in the tank in the form of an elastic membrane or a bellows with a return spring, to separate warm och cold coolant. This is an expensive and unnecessarily complicated design. The second type is filled with steel wool, mineral wool or has a set of parallel channels which are said to prevent mixing of warm and cold coolant. It is possible that they may achieve a certain reduction in mixing through said measures, but they are not sufficient for the accumulator tank to achieve the desired function. The purpose of the present invention is to achieve an internal combustion engine of the type described by way of introduction, which has an accumulator tank with a flow barrier which effectively impedes the mixing of warm and cold coolant. This is achieved according to the invention by virtue of the fact that the flow barrier is formed of a flow-optimized conduit which is arranged so that certain portions of the conduit lie side by side with other portions of the conduit and in a plurality of layers. The invention will be described in more detail below with reference to examples shown in the accompanied drawings, where Figure 1 shows a schematic representation of a first embodiment of an internal combustion engine according to the invention, Figure 2a and 2b show a schematic front view and side view, respectively, of a first embodiment of a flow barrier in the accumulator tank in Figure 1, and Figure 3 shows a schematic side view of a second embodiment of a flow barrier. Figure 1 shows an internal combustion engine M with a coolant flow schematically indicated through the same. The internal combustion engine M drives a coolant pump Pm. which has free throughflow in its inactive state, and which circulates coolant during operation of the internal combustion engine M. The mechanical coolant pump Pm is connected on its suction side via a hose HI to the lower portion of a radiator R (air/coolant heat exchanger) and on the pressure side to the lower portion of the coolant channels of the internal combustion engine M. The upper portion of the coolant channels of the engine M are connected, firstly, via a thermostatic valve T2 and a hose H2, to the upper portion of the radiator R and, secondly, in parallel thereto, via a controlled valve VI and a thermostatic valve Tl, connected to the insulated hose H3, to a well insulated accumulator tank A. The other end of the accumulator tank A is connected via an insulated hose H4, to the suction side of an electric circulation pump Pe which has free flowthrough in its inactive state. The electric circulation pump Pe is connected on the pressure side, via an insulated hose H5, to the mechanical coolant pump Pm and the lower portion of the coolant channel system of the engine M. A hose H6 connects, via a non-return valve V2, the upper portion of the coolant channel system of the engine M to the suction side of the mechanical coolant pump Pm. When the engine M has been started, coolant, with the aid of the mechanical coolant pump Pm, circulates through the coolant channels of the engine M via the hose H6 and the non-return valve V2 back to the mechanical coolant pump Pm. In the other units and hoses there is no circulation of coolant, and this accelerates the heating of the engine M. When the engine M has reached its operating temperature, the thermostatic valve Tl is gradually opened and coolant begins to flow out from the upper coolant channels of the engine M, through the hose H3 and the accumulator tank A, via the hose H4 through the electrical circulation pump Pe and via the hose H5 to the mechanical coolant pump Pm and the lower coolant channel system of the engine M. The temperature increases gradually in the accumulator tank A to the same temperature as in the engine M, and the thermostatic valve Tl will be completely open. Coolant in the engine M and the accumulator tank A has now in sequence been rapidly heated to full operating temperature. If the engine M continues to operate, the thermostatic valve T2, which has a somewhat higher opening temperature than the thermostatic valve Tl, will, in a known manner, guide the coolant via the hose H2 to the radiator R and via the hose H 1 back to the mechanical coolant pump Pm and the coolant channels of the engine M. Thus the temperature of the engine M is kept at an even level. When the engine M is turned off and the temperature drops, the thermostatic valves T2 and Tl close and and the circulation through the accumulator tank A ceases. When the engine M is to be restarted and the ignition is turned on, the electrical- circulation pump Pe starts, the control valve VI opens and the non-return valve V2 closes. The accumulated heated coolant in the accumulator tank A now flows via the hose H4, the electrical circulation pump Pe and the hose H5 to the mechanical coolant pump Pm and the lower portion of the coolant channel system of the internal combustion engine M, thus filling the engine M with warm coolant. The cold coolant, which was in the coolant channels of the engine M, flows at the same time via the controlled valve VI and the hose H3 over to the accumulator tank A. The electrical circulation pump Pe then is shut off, the controlled valve VI closes and the non-return valve V2 opens. The process is very rapid. Shutting off of the electrical circulation pump Pe and the closing of the controlled valve VI after a completed heating cycle can be accomplished in a number of different manners, e.g. by time control or signalled completion of a cycle. Under certain conditions it can be an advantage to have a flow direction, opposite to that described above, of the coolant when heating the engine. The non-return valve V2 must then be replaced by a controlled valve. The engine M is now heated and can be started. If the engine M has recently been operated and is to be restarted, then it is suitable to eliminate the automatic transfer of warm coolant from the accumulator tank A. This is controlled, for example, by breaking the current to the electrical circulation pump Pe and the controlled valve VI by means of a thermostat, as long as the engine M is judged to be sufficiently warm. The accumulator tank A must be placed as close to the thermostat Tl as possible, in order to avoid, when the engine is turned off, warm coolant, due to layering, from wandering from the accumulator tank A via the upper portion of the hose H3 and there being cooled off and then running back to the accumulator tank A via the lower portion of the hose H3. In this manner the hose H3, despite the fact that there is no free flow-through in this state, can cause cooling off of the accumulator tank A. It is important that one has an even parallel flow of coolant through the entire cross section and along the entire length of the accumulator. Otherwise there will be an unavoidable mixing between warm and cold coolant. This can be solved by mounting a flow barrier. A simple and uncomplicated accumulator tank, which does not mix warm and cold coolant, is achieved according to the invention by a flow barrier in the form of a long flow-optimized conduit which, to reduce the exposed surface, is wound so that the conduit lies side by side with itself and in a plurality of layers. In this manner, a mini¬ mum of exposed surface is obtained for a given length of conduit. This can be arranged in various manners. The embodiment can, for example, be a conduit wound in a spiral shape FB 1, as shown in Figs 2a and 2b, where one spiral connects to the next spiral and so on. In this manner, only the outer winding of the respective spiral and the two end sides are exposed to the outer surroundings. Another embodiment can be a conduit wound in a coil shape FB2, as shown in Fig 3, where the exposure to the outer sur-roundings will be similar to that of the spiral embodiment.

Claims: Claims 1. Liquid-cooled internal combustion engine (M) with an engine block provided with coolant channels and a coolant system communicating with the coolant channels, said coolant system comprising a radiator (R), a coolant pump (Pm) and a thermostatic valve (T2) arranged in an inlet conduit (H2) from the radiator (R), an accumulator tank (A) containing a flow barrier (FBI, FB2) and an inlet and outlet, which communicate with the coolant channels in the engine block, and a circulation pump (Pe) communi-cating with the coolant channels and the accumulator tank (A) of the engine block, characterized in that the flow barrier (FBI, FB2) of the accumulator tank is formed of a flow-optimized conduit, which is arranged so that certain portions of the conduit lie side by side with other portions of the conduit and in a plurality of layers. 2. Engine according to Claim 1, characterized in that the flow barrier is a conduit (FBI) wound in spiral-shape. 3. Engine according to Claim 1, characterized in that the flow barrier is a conduit (FB2) wound in coil-shape.

Inventors: LINDSTROEM CHRISTER, LINDSTROEM, CHRISTER
Applicants: BETA MASKIN AB, LINDSTROEM CHRISTER, LINDSTROEM, CHRISTER
Application year: 1996
Main classification: F02N17
IPC codes: F01P11, F02N17