JPH0216990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine evaluation test method, and particularly to an engine cooling/heating cycle test assuming usage conditions in a cold region.

[Conventional technology]

Generally, in cold regions, the vehicle temperature is -30°C to -40°C.
After leaving the car under the temperature conditions of 200 to 300, the engine is started and driven at high speed, then the engine is stopped again and the car is left at a low temperature. In this case, a large thermal shock will be applied to the engine. As a result, seals such as gaskets may expand and contract repeatedly due to large temperature changes and deteriorate, which may cause coolant (hereinafter referred to as LLC) leaks and oil leaks.

Conventionally, in order to reproduce the severe environmental conditions of vehicles used in cold regions as described above in in-house bench tests, it was necessary to equip a cold room with an LLC cooling system and an oil cooling system, and then transport the engine into this cold room. If you start the engine and run it at maximum engine speed under low temperature, then stop it and leave it for a while, the second problem will occur.
With the prescribed cooling and heating cycle pattern as shown in the figure,
The engine was operated and an evaluation test was conducted.

[Problem to be solved by the invention]

This test method had the following drawbacks.

Tests using a cold room are extremely expensive due to the high installation and operating costs of the cold room.

For the test, examiners must enter and leave a cold room, where there is a large temperature difference, and sufficient consideration must be given to the examiner's physical condition.

In conventional tests, the inventors found that it was not necessary to cool the entire air in the cold room during cold storage, but rather that the cooled LLC and oil that was circulated during the engine shutdown and storage were kept at a specified temperature. They discovered that it is possible to reproduce the same thermal shock conditions as in actual use by cooling it to a certain temperature.

This means that the results of measuring the wall temperature of the engine block when forced circulation of LLC and oil cooled to a specified temperature at room temperature show that the engine block has been cooled to the same temperature as in a test using a cold room. It appears that thermal shocks are also comparable.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a thermal cycle test method for an engine that can provide a thermal shock equivalent to that in natural conditions in a cold region to an engine at room temperature.

[Means to solve the problem]

The purpose of this is to maintain the engine coolant (hereinafter referred to as "LLC") and oil at a predetermined operating temperature to prevent engine seizure during the thermal cycle in which the engine is operated at high speed during engine thermal cycle tests. During the cold cycle, the engine is circulated and supplied to the engine while the engine is running, and the engine is stopped and left unattended.In order to cool the engine while it is stopped, the LLC and oil that have been cooled to a predetermined storage temperature assuming a cold region are supplied to the engine. This is accomplished using an engine thermal cycle test method that circulates and supplies air to the engine and shields the engine with air that has been dehumidified to an extent that does not cause dew or ice formation on the engine surface.

The reason why the engine is shielded with dehumidified air during the cold cycle is to prevent moisture in the air from condensing or freezing on the engine surface by cooling the engine in a normal temperature atmosphere.

[Effect]

In a room-temperature test room, the LLC cooling system and oil cooling system cool the engine during the cold cycle.
The LLC and oil are forcibly maintained at a predetermined temperature, which is the same as if the entire engine were under the same temperature conditions. In addition, the LLC and oil in the engine are lowered to a predetermined storage temperature under room temperature conditions, but the engine is shielded from moisture-containing air with dehumidified air, so there is no chance of condensation or ice forming on the engine. Tests can be carried out without any problems occurring.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a system configuration diagram showing a test apparatus used to carry out the test method of the present invention, and FIG. 2 is a time chart showing an example of a test pattern for a thermal cycle test.

In Fig. 1, reference numeral 1 is an engine to be subjected to the main cold/heat cycle test, and reference numeral 2 is an engine connected to the crankshaft of this engine 1, which absorbs the power generated by this engine 1 and measures and displays the generated horsepower. The dynamometer, code 3, is a high-temperature LLC control device that cools and maintains the cooling LLC at a predetermined operating temperature (80°C to 110°C) to prevent engine 1 from seizing while engine 1 is running. A high-temperature LLC cooler that is connected by piping to the cooling water outlet and the cooling water return port of the cylinder block, and exchanges heat between the LLC supplied from the engine 1 circulating inside and the cooling water for cooling the LLC. It consists of 7.

Reference numeral 4 is for cooling the LLC to a temperature (-40°C to -30°C) assuming the lowest temperature in a cold region when the engine 1 is stopped and left unattended.
It is an LLC cooling device, and the high temperature LLC control device 3
A low-temperature controller is connected in parallel with this high-temperature LLC control device 3 to the piping of
It consists of an LLC pump 8 and a low-temperature LLC cooler 9 connected in series with the low-temperature LLC pump 8 to cool the LLC. This low temperature LLC cooler 9 is
In order to cool the refrigerant to the above-mentioned storage temperature, it is connected to a refrigerator 16 consisting only of a compressor, and the liquefied refrigerant sent from this refrigerator 16 is vaporized in the low-temperature LLC cooler 9, which is also a condenser. It is a direct expansion type cooler.

Reference numeral 5 designates a high-temperature oil control device that cools and maintains lubricating oil at a predetermined operating temperature (80°C to 110°C) to prevent the engine 1 from seizing while the engine 1 is operating. A high-temperature oil pump 10 that is connected to the drain of the pan and a separately drilled hole by piping to suck oil accumulated in the oil pan of the engine 1, and oil that is connected in series with this high-temperature oil pump 10 and circulates inside. It is comprised of a high temperature oil cooler 11 that exchanges heat between the oil and the cooling water for cooling the oil.

Note that cooling channels for the high-temperature LLC cooler 7 and the high-temperature oil cooler 11 are not shown.

Reference numeral 6 denotes an oil cooling device for cooling the oil to a storage temperature (-40°C to -30°C) assuming the lowest temperature in a cold region when the engine 1 is stopped and left. A low-temperature oil pump 12 that is connected to the piping of the high-temperature oil control device 5 in parallel with the high-temperature oil control device 5 and sucks oil from the engine 1;
The low temperature oil cooler 13 is connected in series with the oil cooler 13 to cool the oil. This low temperature oil cooler 13 is connected to the refrigerator 16 in order to cool the oil to the temperature at which it is left.
This is a direct expansion type cooler in which the liquefied refrigerant sent from the cooler is vaporized in the low temperature oil cooler 13, which also serves as a condenser. The low-temperature oil cooler 13 has a screw conveyor-like mechanism in order to efficiently cool the low-temperature, high-viscosity oil.

In the middle of the piping connecting the high temperature LLC control device 3, LLC cooling device 4, high temperature oil control device 5, and oil cooling device 6 to the engine 1, high temperature LLC on-off valves 1 are provided on the outbound and return routes, respectively.
4, 14, low-temperature LLC on-off valves 18, 18, high-temperature oil on-off valves 15, 15, and low-temperature oil on-off valves 19, 19 are interposed.

Further, the LLC cooling device 4 and the oil cooling device 6 may be provided with a tank, a bypass valve, or the like (not shown) for the purpose of ease of operation and control. Among these, the tank is used in the LLC cooling device 4 to store a certain amount of cooled LLC in the LLC cooling device 4 so that there is no shortage of LLC when rapid cooling is required. In this case, the tank in the oil cooling device 6 is made to hold the same amount of oil as that entering the oil pan of the engine 1, and as shown in the bottom diagram of FIG. When the oil is stopped after being operated at high speed, high-temperature oil is extracted and cooled oil is supplied, the oil can be cooled by putting it in a tank in an oil cooling device 6 in advance.

Further, the bypass valve bypasses the pumps 8, 12 and coolers 9, 13 in the LLC cooling device 4 and oil cooling device 6, and controls the amount of LLC and oil bypassed here. This allows oil temperature control.

Finally, reference numeral 17 is a dehumidifier that dehumidifies the sucked air and supplies the dehumidified air to the engine 1.

Next, a method of performing a cold/hot cycle test on the engine 1 using the cold/hot cycle test apparatus configured as described above will be described.

As shown in Fig. 1, the crankshaft of engine 1 is connected to a dynamometer 2 that absorbs the output of this engine, and the engine 1 is repeatedly operated and stopped, for example, in a cold/hot cycle pattern as shown in Fig. 2. In the cold cycle test, first in the cold cycle, for the LLC system, with the engine 1 stopped, the high-temperature LLC on-off valve 14 is closed, the low-temperature LLC on-off valve 18 is opened, the LLC cooling device 4 is operated, and the engine 1 is turned off. The LLC sucked from the engine by a low temperature LLC pump 8 is cooled by a low temperature LLC cooler 9, and then returned to the engine 1.

On the other hand, regarding the oil system, the high-temperature oil on-off valve 15 is closed, the low-temperature oil on-off valve 19 is opened, the oil cooling device 6 is operated, and the oil sucked from the oil pan of the engine 1 by the pump 12 is transferred to the low-temperature oil cooler. Cool it down at step 13 and return it to the oil pan.

Engine 1 indoors at room temperature -40℃ to -30℃
If it is cooled to near ℃, moisture in the air will condense or freeze on the engine surface, causing electrical problems and making it difficult to find water leaks in the engine 1. Therefore, during the cold cycle, the dehumidifier 17 is
is operated to shield the engine 1 from moisture-containing air with dry air.

Next, in the thermal cycle, the engine 1 is started and rotated, and immediately after starting, it is operated at idle, then operated at full load and maximum rotational speed, and finally, idle operation is performed again to complete this thermal cycle.

At this time, regarding the LLC system, the high-temperature LLC on-off valve 14 is opened, the low-temperature LLC on-off valve 18 is closed, and the high-temperature LLC control device 3 is operated, so that the temperature of the high-temperature LLC sent from the engine 1 is adjusted to the operating temperature. Heat this LLC to high temperatures so as not to exceed
Cool with LLC cooler 7.

On the other hand, regarding the oil system, the high-temperature oil on-off valve 15 is opened, the low-temperature oil on-off valve 19 is closed, and the high-temperature oil control device 5 is operated to prevent the oil temperature in the engine 1 from exceeding the operating temperature. Oil sucked from the pan by a low-temperature oil pump 12 is cooled by a high-temperature oil cooler 11 and returned to the oil pan again.

In this way, a thermal cycle test of the engine 1 can be conducted in a room temperature laboratory without using a cold room.

〔Effect of the invention〕

As is clear from the above, according to the present invention, it is possible to provide the engine with the same thermal shock that the engine receives in a cold region at room temperature. In addition, unlike when using a cold room, there is no need to cool the entire cold room, so the cost of the test equipment can be kept much lower, and it is possible to conduct experiments with less energy, keeping running costs low. Can be done. Furthermore, since the thermal cycle test can be carried out at room temperature, there is an advantage in that workability is good and the working environment is also good for the testers.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram showing a test apparatus used to carry out the test method of the present invention, and FIG. 2 is a time chart showing an example of a test pattern for a thermal cycle test. 1...Engine, 2...Dynamometer, 3...High temperature
LLC control device, 4...LLC cooling device, 5...High temperature oil control device, 6...Oil cooling device, 7...
...High temperature LLC cooler, 9...Low temperature LLC cooler, 1
1... High temperature oil cooler, 13... Low temperature oil cooler, 8... Low temperature LLC pump, 10... High temperature oil pump, 12... Low temperature oil pump, 14...
...High temperature LLC on/off valve, 15...High temperature oil on/off valve,
18...Low temperature LLC on/off valve, 19...Low temperature oil on/off valve, 16...Freezer, 17...Dehumidifier.

Claims (1)

[Claims] 1. In engine thermal cycle tests, during the thermal cycle in which the engine is operated at high speed, engine coolant (hereinafter referred to as
LLC) and oil are circulated and supplied to the engine while maintaining it at a predetermined operating temperature to prevent engine seizure, and during the cold cycle, when the engine is stopped and left alone, the engine is cooled while it is stopped. The engine is characterized by circulating and supplying the LLC and oil cooled to a predetermined storage temperature assuming a cold region to the engine, and shielding the engine with air that has been dehumidified to the extent that dew condensation and ice do not form on the engine surface. Engine cold and heat cycle test method.