JP2010096047A - Cooling water circuit for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling water circuit for an internal combustion engine reducing an amount of cooling water supplied to an engine when the engine has a low load while using a mechanically driven water pump. <P>SOLUTION: In the cooling water circuit 1 for the internal-combustion engine including the water pump 4 driven by an engine rotation system between the engine 2 and a radiator 3, there are provided a by-pass water passage 5 that connects an engine side of the water pump 4 to a radiator side of the same, and a thermostat 6 provided to the by-pass water passage 5, increases an opening thereof to increase a flow rate in the by-pass water passage 5 when the water temperature of the cooling water from the radiator 3 is low due to the low load on the engine, and decreases the opening thereof to decrease the flow rate in the by-pass water passage 5 when the water temperature of the cooling water from the radiator 3 is high due to the high load on the engine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cooling water circuit for an internal combustion engine that can reduce the amount of cooling water sent to the engine when the engine is under a low load while using a mechanically driven water pump.

  In a conventional cooling water circuit for an internal combustion engine, a water pump for feeding cooling water from the radiator to the engine is provided between the engine and the radiator. The water pump is mechanically driven via a belt by a crankshaft. Therefore, when the engine speed is low, the water pump speed is low and the amount of cooling water fed from the radiator to the engine is not large. Conversely, when the engine speed is high, the water pump speed is also high, so that the amount of cooling water fed from the radiator to the engine is large.

  With the above configuration, the cooling water circuit of the conventional internal combustion engine has a small amount of cooling water sent to the engine when the engine speed is low, but the amount of cooling water sent to the engine increases when the engine speed becomes high. It takes more heat from the engine and cools it more powerfully.

JP 2005-133559 A

  A conventional cooling water circuit of an internal combustion engine is mechanically driven by an engine rotation system in which a water pump rotates together with the engine, so that the discharge amount of the water pump is uniquely determined by the engine speed. Therefore, the amount of cooling water sent to the engine is uniquely determined by the engine speed. When the engine speed is low, the amount of cooling water sent to the engine is small, and when the engine speed is high, the cooling water sent to the engine. There will be a lot of water.

  On the other hand, in an engine, when the engine speed is high and the engine is operated at a high load, as described above, a large amount of cooling water is fed and cooled strongly, which is preferable. However, even when the engine speed is high, when the engine is operated at a low load, the water temperature in the engine is not so high, so it is not necessary to cool it very strongly.

  As described above, in the cooling water circuit of the conventional internal combustion engine, since the discharge amount of the water pump depends only on the engine speed, the amount of cooling water fed into the engine is adjusted regardless of the engine load. . As a result, in the case of a low engine load, there is a problem that the engine is in a supercooled state where it is cooled more than necessary.

  Further, the fact that the water pump is driven more than necessary means that the output energy of the engine is consumed more than necessary, and there is a problem that useless driving loss occurs.

  The water pump can be configured not to be mechanically driven by the engine rotation system, but to adjust the discharge amount of the water pump by a command from an ECU (engine control device) using an electric water pump. However, since the electric water pump is larger in size than the flow capacity, if an electric water pump having a sufficiently large flow capacity comparable to the mechanical drive type water pump is used, the space in the engine room And the layout becomes difficult. In addition, since the electric water pump is more expensive than the mechanically driven water pump, it becomes an obstacle to cost reduction of the vehicle.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cooling water circuit for an internal combustion engine that solves the above-mentioned problems and can reduce the amount of cooling water sent to the engine when the engine is under a low load while using a mechanically driven water pump. It is in.

  In order to achieve the above object, the present invention connects an engine side of a water pump and a radiator side in a cooling water circuit of an internal combustion engine having a water pump driven by an engine rotation system between the engine and a radiator. When the coolant temperature from the radiator is low due to the engine low load, the opening is increased to increase the flow rate of the bypass water channel, and the engine high load from the radiator. And a thermostat for reducing the opening degree so as to reduce the flow rate of the bypass water channel when the coolant temperature is high.

  The present invention exhibits the following excellent effects.

  (1) The amount of cooling water sent to the engine can be reduced when the engine is under a low load while using a mechanically driven water pump.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, a cooling water circuit 1 for an internal combustion engine according to the present invention includes an internal combustion engine having a water pump 4 driven by an engine rotation system (not shown) between an engine 2 and a radiator 3. In the cooling water circuit 1, a bypass water channel 5 that connects a water pump outlet 4 a that is the engine side of the water pump 4 and a water pump inlet 4 b that is the radiator side, and a bypass water channel 5 that is provided in the bypass water channel 5, and the radiator 3 for low engine load. In order to decrease the flow rate of the bypass channel 5 when the coolant temperature from the radiator 3 is high due to high engine load, the opening degree is increased to increase the flow rate of the bypass channel 5 when the coolant temperature from the engine is low. A thermostat (hereinafter, referred to as a water amount adjusting thermostat) 6 for reducing the opening degree is provided.

  Although not shown, a cooling water passage for circulating cooling water is provided inside the engine 2. Between the engine 2 and the radiator 3, a radiator suction water channel 7 that connects the cooling water channel inside the engine 2 and the radiator 3 is provided. A warm-up thermostat 8 is conventionally provided in the radiator suction water channel 7. The warm-up thermostat 8 is closed when the water temperature is low because the engine warm-up has not been achieved, and shuts off the water flow in the radiator suction water channel 7, and is opened when the engine warm-up is achieved and the water temperature is high, and the radiator suction water channel 7. The water flow is released. The opening / closing temperature of the warm-up thermostat 8 is different from the opening adjustment temperature of the water amount adjusting thermostat 6. The warm-up thermostat 8 in FIG. 1 is a so-called outlet thermo (exit thermo), but may be a so-called inlet thermo (inlet thermo).

  The operation will be described below.

  It is assumed that the engine 2 is already warmed up, the warming-up thermostat 8 is opened, and the water flow in the radiator suction water channel 7 is released. When the water pump 4 is mechanically driven by the engine rotation system, the cooling water passes from the inside of the engine 2 through the radiator suction water passage 7, the radiator 3, and the water pump 4 to return to the inside of the engine 2 again.

  Here, it is assumed that the engine speed is high and the engine 2 is operated at a high load. Since the engine has a high load, the temperature of the cooling water inside the engine 2 is considerably high, and the temperature of the cooling water subjected to heat exchange by the radiator 3 is relatively high. This cooling water passes through the water pump 4 and flows to the engine side. The water amount adjusting thermostat 6 operates in a direction to reduce the opening degree because the temperature of the cooling water from the radiator 3 is high. Since the opening degree of the water amount adjusting thermostat 6 is decreased, the flow rate of the cooling water flowing through the bypass water channel 5 is decreased. Therefore, most of the cooling water that has flowed out to the water pump outlet 4 a on the engine side of the water pump 4 flows into the engine 2. The engine 2 is cooled strongly by feeding a large amount of cooling water.

  Next, it is assumed that the engine 2 is operated at a low load although the engine speed is high. Since the engine is lightly loaded, the temperature of the cooling water inside the engine 2 is lower than that when the engine is heavily loaded, and the temperature of the cooling water subjected to heat exchange with the radiator 3 is considerably low. This cooling water passes through the water pump 4 and flows to the water pump outlet 4a on the engine side. The water amount adjusting thermostat 6 operates in the direction of increasing the opening degree because the temperature of the cooling water from the radiator 3 is low. As the opening degree of the water amount adjusting thermostat 6 increases, the flow rate of the cooling water flowing through the bypass water channel 5 increases. Therefore, most of the cooling water that has flowed out to the engine side of the water pump 4 flows into the bypass water channel 5 and returns to the water pump inlet 4 b that is the radiator side of the water pump 4. The engine 2 is appropriately cooled by a relatively small amount of cooling water.

  Thus, in the case of a low engine load, the cooling water flowing into the engine 2 is reduced, so that the engine 2 is not overcooled to be cooled more than necessary.

  On the other hand, the cooling water flowing into the bypass channel 5 is circulated again to the bypass channel 5 by the water pump 4, but the bypass channel 5 is consumed by the water pump 4 because the resistance to the water flow is smaller than in the engine. Less energy. Therefore, the output energy of the engine 2 is not consumed so much and no unnecessary driving loss occurs.

  With reference to FIG. 2, characteristics of the flow rate to the engine 2 and the bypass water channel 5 with respect to the opening degree in the water amount adjusting thermostat 6 will be described.

  As shown in FIG. 2, the flow rate of the water pump 4 is constant regardless of the opening degree of the water amount adjusting thermostat 6. When the opening degree of the water amount adjusting thermostat 6 is 0, the entire amount of cooling water of the water pump 4 flows into the engine 2. As the opening degree of the water amount adjusting thermostat 6 increases, the amount of cooling water returning from the water pump outlet 4a to the water pump inlet 4b increases, and accordingly, the amount of cooling water flowing into the engine 2 decreases.

  With reference to FIG. 3, the characteristics of the driving loss of the engine 2 with respect to the opening degree in the water amount adjusting thermostat 6 will be described.

  As shown in FIG. 3, when the opening degree of the water amount adjusting thermostat 6 is 0, the driving loss of the engine 2 is the largest. As the opening degree of the water amount adjusting thermostat 6 increases, the drive loss of the engine 2 decreases. Considering together with FIG. 2, when the entire amount of cooling water of the water pump 4 flows into the engine 2, the drive loss of the engine 2 is the largest. As the amount of cooling water flowing into the engine 2 decreases, the drive loss of the engine 2 decreases.

It is the schematic of the cooling water circuit of the internal combustion engine which shows one Embodiment of this invention. It is a characteristic view of the flow volume with respect to the opening degree in the thermostat for water quantity adjustment. It is a characteristic view of the engine drive loss with respect to the opening degree in the thermostat for water quantity adjustment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooling water circuit of internal combustion engine 2 Engine 3 Radiator 4 Water pump 5 Bypass water channel 6 Water quantity adjustment thermostat 7 Radiator suction water channel 8 Warm-up thermostat

Claims (1)

In an internal combustion engine cooling water circuit having a water pump driven by an engine rotation system between an engine and a radiator,
A bypass water channel connecting the engine side and the radiator side of the water pump;
When the coolant temperature from the radiator is low due to the engine low load, the opening is increased to increase the flow rate of the bypass channel, and the coolant from the radiator is high because of the engine high load. A cooling water circuit for an internal combustion engine, comprising: a thermostat for reducing an opening degree so as to reduce a flow rate of the bypass water channel when a water temperature is high.

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