JPS58106125A - Control method of cooling fluid temperature in internal-combustion engine - Google Patents

Abstract

PURPOSE:To stop cooling fluid at a low load and hold the fluid to a high temperature range, by providing a control valve, closed at a high load while opened at the low load, in a bypass passage of small flow resistance bypassing cooling water from a delivery side to suction side of a water pump. CONSTITUTION:A bypass passage 40 of small flow resistance is connected to a delivery side 60a and suction side 60b of a water pump 6, and a bypass flow controller 50 is interposed in said bypass passage 40. The controller 50 is constituted by a diaphragm, dividing a unit into an upper chamber 501 introduced with suction negative pressure and bottom chamber 502 communicated to the atmosphere, and a valve 503 connected to said diaphragm, if negative pressure is intensified, the valve 503 is opened at a low load, and cooling fluid is circulated with the passage 40 of small flow resistance as the center almost not flowing into a cooling system reaching a radiator via a water jacket of an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the temperature of a coolant in a liquid-cooled internal combustion engine.

Generally, in a liquid-cooled internal combustion engine, a thermostat provided in the cooling system does not control the temperature of the coolant circulating in the cooling system to be within a temperature range of about 85°C. It is desirable that this temperature range be higher in terms of reducing the amount of HC in the exhaust gas and improving fuel efficiency. However, if this is high, the wall temperature of the combustion chamber will rise more than necessary under high load, heating the air-fuel mixture and causing non-king during acceleration etc., and durability will become a problem due to thermal distortion. Therefore, from the viewpoint of preventing knocking under high loads and durability due to thermal distortion, a lower value is desirable.

From this point of view, coolant temperature control methods have been proposed that keep the coolant temperature in a relatively low range during high loads and keep the coolant temperature in a relatively high range during other medium and low loads. , Utility Model Application Publication No. 54-142722 is one of them.

FIG. 1 shows the cooling system shown in Utility Model Application No. 54-142722, and FIG. 2 shows the cooling liquid temperature control device shown in FIG.

The coolant cooled by the radiator 1 is transferred to the water pump 6
After passing through the water jacket in the engine 2 via the coolant passage 3, the coolant is sent to the coolant temperature control device, and then enters the radiator 1 again via another coolant passage 4.
Coolant circulation takes place. The coolant temperature control device is
The flow rate of the coolant is controlled according to the engine load condition to provide the engine with the optimum coolant temperature.

As shown in FIG. 2, the coolant temperature control device includes a wax-type thermostat 12 held between a water outlet 10 provided in the engine body, a water outlet housing, and a zinc 11. This thermostat 12 has a container-shaped temperature sensing part 13 and a piston 14 that slides relatively up and down inside the temperature sensing part 13. The temperature sensing part 13 is equipped with solid wax and elastic rubber. The head of the piston 14 is configured such that the upward biasing force is suppressed by the operation of a control piece 15, which will be described later.

Therefore, as the temperature of the engine coolant rises and the wax melts and expands, the resulting pressure causes
As long as the head of the piston 140 is restrained by the control piece 15, the temperature sensing portion 13 is pushed downward. 7
is a thermostatic valve installed outside the temperature sensing part 13,
When the thermostand 12 is not in operation, the spring force of the spring 17 presses against the fixed valve seat 18 to close the coolant passage 3.

The control piece 15 is attached to a diaphragm 21 of a control piece actuating diaphragm device bundle, and the diaphragm device is attached to the meter outlet housing 11 via a seal member 22. The upper chamber n of the diaphragm and the device, which is divided into upper and lower parts by the diaphragm 21, is a negative pressure chamber, and the lower chamber is communicated with the atmosphere. The negative pressure chamber unit is connected to a negative pressure source such as an intake manifold (not shown) via a negative pressure delay valve 5, and the intake negative pressure is guided to the negative pressure chamber unit according to engine load fluctuations. .

Reference numeral 26 is a stopper provided at the upper part of the negative pressure chamber unit, and controls the upward movement of the control end 15a when the control end 15a fits inside the groove of the guide member of the thermostat 12 and slides up and down. A spring is provided in the negative pressure chamber η, and when the negative pressure introduced into the negative pressure chamber becomes small and approaches atmospheric pressure, the spring force moves the diaphragm 21 and the control piece 15 to the position shown in the figure. return.

With the above configuration, during high-load operation, the suction negative pressure of the intake manifold is relatively small, so the control piece 15 is maintained at a position where the distance between its end 15a and the piston 14 is small. Therefore, when the cooling water temperature rises and the wax in the temperature sensing part 13 melts and expands, the free end of the head of the piston 140 immediately comes into contact with the end 15a of the control piece 15, and a biasing force that tries to extend upward is generated. is restrained by the spring force of the spring. Therefore, the temperature sensing portion 13 of the thermostat 12 is pushed downward, and the thermostat valve 16 is opened. That is, when the engine is under high load, the thermostat 12 opens the valve at a large valve opening at a relatively early stage when the temperature of the cooling water rises, so the temperature of the cooling water at the time when the valve starts to open is relatively low. , e.g. 70℃
It is kept forward and backward. On the other hand, when the engine is under low load, a relatively large suction negative pressure is introduced into the negative pressure chamber n, so the control piece 15 is pulled upward. Therefore, as the cooling water temperature rises, the wax in the temperature sensing part 13 expands and the piston 1
4 extends upward, it does not immediately contact the control end 15a, and the opening of the thermostat is delayed, so that the temperature is kept relatively high compared to when the load is high.

According to the above configuration, it is possible to control the temperature of the coolant according to the engine load condition, but since the combination of the diaphragm and thermostat detects a high load and opens the thermostat, Because it takes time for the set value of the coolant temperature to change and for the coolant to reach the internal combustion engine from the radiator, the coolant temperature inside the engine does not change quickly even under high load conditions. During this period, the engine does not reach a low temperature range but remains in a high temperature range for a short period of time, and during this period knocking may occur, which may result in inoperability or damage to the engine.

The present invention has been made based on this point of view, and its purpose is to provide a cooling system that not only increases the temperature of the coolant during low loads, but also that can quickly prevent the closing of low temperature areas during high loads and transitions. The object of the present invention is to provide a liquid temperature control method.

A feature of the present invention for achieving this object is that in a method for controlling the coolant temperature of a liquid-cooled internal combustion engine, the coolant is bypassed from the discharge side of the water pump to the suction side. It has a bypass passage with low resistance and a coolant flow control valve that controls the coolant flow rate in the bypass passage according to the load condition of the engine, and during high load operation, the coolant flow control valve is closed and the cooling system is closed. circulate the coolant,
The method of controlling the coolant temperature of an internal combustion engine includes opening the valve during low load operation to guide the flow of the coolant to the bypass passage, thereby substantially stopping the circulation of the coolant in the cooling system.

The present invention will be explained in detail below with reference to the drawings.

FIG. 3 shows an example of a configuration for carrying out the coolant temperature control method according to the present invention, and the same reference numerals as in FIG. 1 indicate the same components.

In the figure, the recess is a coolant temperature control device and has the wax-type thermostat (not shown) described in FIG. 2, but no diaphragm device is provided. The free end of the piston (corresponding to the piston 14 in FIG. 2) of this thermostat is fixed to the water outlet of the engine body, and the valve opening temperature is set at around 85°C. Reference numeral 40 denotes a coolant bypass passage, which is provided to bypass the coolant from the discharge side 60a of the water pump 6 to the suction side 60b. Water pump discharge side 60a
is located on the water jacket inlet side of the engine 2, so that the coolant discharged by the water pump is guided to the water jacket or to the bypass passage.

This bypass passage 40 does not cross the inside of the engine (
, that is, as shown by the broken line arrow (b), from the discharge side 6oa of the water pump 6 to the suction side 60 by crossing the inside of the engine.
As shown by the solid arrow mark), the coolant is routed from the coolant outlet to the outside of the engine near the discharge side 60a of the water pump 6 to the coolant passage 3 without crossing the inside of the engine. It is connected to the suction side 60b of the water pump 6. The bypass passage 40 is designed so that the resistance to the flow of the coolant is smaller than that of the coolant passage of the cooling system including the water jacket of the engine 2, the coolant temperature control device blades and the radiator 1, i.e. it is short and internal. -Consists of passages with large diameter.

Therefore, if the bypass passage 40 is open, most of the coolant discharged from the water pump will be sent to the suction side 60b of the water pump through the bypass passage 40.
It will circulate mainly through the bypass passage.

Such a bypass passage 40 is provided with a bypass flow rate control device that controls the flow rate within the bypass passage. The upper chamber 501 is separated by a diaphragm between the control devices.
Negative pressure is introduced into the upper chamber 501 from an intake manifold (not shown), and the lower chamber 5
02 leads to the atmosphere. Upper chamber 501 and lower chamber 502
A bypass passage opening/closing valve 503 for opening and closing the bypass passage 40 is provided on the diaphragm that separates the bypass passage 40 from the intake manifold.

If the engine is operated at low load with the above configuration,
Since the negative pressure in the intake manifold and therefore the negative pressure in the upper chamber 501 of the bypass flow control device becomes large, the valve 50
3 will be opened. As a result, the coolant discharged from the water pump 6 circulates mainly through the bypass passage 40 with low flow resistance, and hardly flows into the cooling system that reaches the radiator via the engine water jacket. This is regardless of whether the thermostatic valve of the coolant temperature control device blade is fully open or not. Therefore, the amount of heat radiated from the radiator 1 decreases, and the coolant temperature increases. In this case, most of the coolant in the water jacket remains in a stagnant state, so the temperature gradient in the water jacket becomes thick (and the coolant temperature near the combustion chamber and cylinder wall of the engine rises. The temperature of the combustion chamber and the walls around the cylinder can be increased, which increases the temperature of the air-fuel mixture, improves combustion, and improves fuel efficiency.Furthermore, the quenching thickness becomes thinner, and the amount of HC emissions is also reduced.

On the other hand, when the engine shifts to high-load operation, the negative pressure in the upper chamber 501 of the bypass flow rate control device becomes small, and the valve 503 does not close. As a result, the bypass passage 40 is closed, so that the coolant discharged from the water pump 6 flows into the water jacket of the engine. As a result, the temperature of the coolant in the water jacket is averaged and there is no temperature gradient, so the temperature of the walls around the combustion chamber and cylinder does not cool rapidly, and the air-fuel mixture is prevented from being heated more than necessary, thereby preventing knocking.

As explained above, according to the present invention, a bypass passage with low flow resistance is provided from the discharge side to the suction side of the water pump, and this is controlled to open and close according to the load condition of the engine. It increases the temperature of the coolant to improve fuel efficiency and reduce HC emissions, as well as quickly shift to high loads.

It is possible to provide a method of controlling the coolant temperature in a low temperature range and preventing knocking.

[Brief explanation of the drawing]

FIG. 1 shows a conventional example of a cooling system for a liquid-cooled internal combustion engine, FIG. 2 shows an example of the structure of the coolant temperature control device shown in FIG. 1, and FIG. This is an example of a cooling system. 1...Radiator 2...Engine 3.4...Cooling fluid passage 6...Water pump (9) ...... Coolant temperature control device 4002
9.9190. Bypass passage 50... Bypass flow rate control device 60a.
...Discharge side 60b...Suction side Patent applicant: Nissan Motor Co., Ltd. Patent application agent Megumi Yamamoto -

Claims (1)

[Scope of Claims] ]) In a method for controlling the temperature of a coolant in a liquid-cooled internal combustion engine, a bypass passage is provided in the cooling system, which bypasses the coolant from the discharge side of the water pump to the suction side, and has a flow resistance smaller than that of the existing cooling system. and a coolant flow control valve that controls the coolant flow rate in the bypass passage according to the engine load condition, and during high load operation, the coolant flow control valve is closed to circulate the coolant in the cooling system. A method for controlling a coolant temperature of an internal combustion engine, characterized in that during low load operation, the valve is opened to guide the flow of the coolant to a bypass passage, thereby substantially stopping the circulation of the coolant in the cooling system. 2) The coolant temperature control method for an internal combustion engine according to claim 1, wherein the bypass passage is provided from near the discharge side of the water pump to the suction side without crossing the inside of the engine.