JPS59134364A - Warming promotor for diesel engine - Google Patents

Abstract

PURPOSE:To promote warming while to improve fuel consumption and to conform with exhaust gas regulation, by sucking air warmed by exhaust gas while performing exhaust gas recirculation under insufficient warming. CONSTITUTION:Upon detection of cooling water temperature below 80 deg.C through a water temperature sensor 13 at start, ECU 14 will turn on a solenoid negative pressure exchange valve 9 to supply negative pressure caused by a pump 16 to the negative pressure side 8a of an actuator 8 while to close the cold air suction path 6 by a cold/warm air exchange valve 10 and to supply warm air in a warming cover 5 to be heated by an exhaust manifold 4 to the upstream side of an air cleaner 2. After elapse of predetermined time, an exhaust recirculation control valve 12 will open to recirculate exhaust gas through a suction pipe 3 where said recirculation is controlled by ECU 14 in accordance to the engine rotation, throttle valve position, etc. Consequently warming is promoted while fuel consumption is improved through utilization of exhaust gas and it will conform to exhaust gas regulation through exhaust gas recirculation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a warm-up device for a diesel engine, and particularly to a device for promoting warm-up.

Diesel engines have good fuel efficiency, low heat loss in the cooling system, etc., but the engine cooling water temperature rises slowly, and even after the engine has warmed up sufficiently, the water temperature may remain high. Therefore, vehicles equipped with heaters that use cooling water as a heat source have the disadvantage that the heaters are slow and have poor effectiveness. In addition, in response to NOx regulations for diesel engines, the exhaust gas temperature is low during idle, low speed, and low load, so engine corrosion is accelerated by sulfur (S) oxides in the exhaust gas. There was a problem in that exhaust gas recirculation (EGR) could not be performed under these conditions.

The present invention was made in order to solve the problems of the prior art, and its purpose is to use the heat of exhaust gas to accelerate engine warm-up and comply with exhaust gas regulations. To obtain a warm-up promotion device for a diesel engine which is also effective for diesel engines.

In order to achieve the above object, the present invention has a configuration including an exhaust gas recirculation passage for recirculating exhaust gas, an exhaust gas recirculation control valve installed in the exhaust gas recirculation passage for passing or blocking exhaust gas, and a heating valve near the exhaust manifold. a warm-up intake passage that takes in fresh air, a cold-air intake passage that takes in outside air, a cold/hot air switching valve that operates to shut off either the warm-air intake passage or the cold-air intake passage, and the warm-up state of the engine. It is equipped with a detection mechanism that detects the engine temperature and a control circuit that controls the exhaust recirculation control valve and the cooling/heating air switching valve in conjunction with this detection mechanism. This is a diesel engine warm-up accelerating device that performs exhaust gas recirculation.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, in which 1 is an engine, 2 is an air cleaner, 3 is an intake pipe, and 4 is an exhaust manifold. 5 is a warm air cover that covers the exhaust manifold 4, and a warm air intake passage 7 is connected to this warm air cover 5.
The other end of the warm air intake passage 7 is open to the upstream side of the air cleaner 2 . A cold air intake passage 6 is connected to the upstream side of the air cleaner 2 and communicates with the outside air, and a cold/hot air switching valve 10 is installed at the confluence of the cold air intake passage 6 and the warm air intake passage 7. Reference numeral 8 denotes an actuator that performs a switching operation of this cooling/heating air switching valve 10, and by introducing negative pressure into the negative pressure chamber 8-a, the cooling/heating air switching method 10 is actuated to close the cold air intake passage 6. It is configured to open the warm air intake passage 7. Reference numeral 9 denotes an electromagnetic negative pressure switching valve that communicates with the negative pressure chamber 8-a of the actuator 8, which is connected to the Pakim pump 16, and is also connected to the electronic control circuit (hereinafter abbreviated as ECU) 14.
It is reverse controlled by the command of Reference numeral 11 denotes an exhaust gas recirculation passage, which connects the exhaust manifold 4 and the intake pipe 3. 1
Reference numeral 2 denotes an exhaust gas recirculation control valve installed in this exhaust gas recirculation passage, which is activated by a command from the ECU 140 to pass or block the exhaust gas recirculation.

Reference numeral 13 denotes a water temperature sensor installed in the engine 1 to detect the engine cooling water temperature, and its output is input to the ECU 14. The ECU 14 still has an engine speed sensor 17,
The output from the throttle opening sensor 18 is input.

The operation of this embodiment having the above configuration will be explained with reference to FIG. 2 as well. In addition, Figure 2 shows 40kI after the engine starts.
This figure shows the relationship among the cooling water temperature, exhaust gas recirculation gas (EGR gas), and warm air intake (F/Intake) during steady driving at Il/H.

When the water temperature sensor 13 detects that the cooling water temperature is below a predetermined temperature, for example 80C, at the same time as the engine starts,
The electromagnetic negative pressure switching valve 9 is energized, negative pressure from the vacuum pump 7616 is introduced into the negative pressure chamber 8-a of the actuator 8, and the cooling/heating air switching valve lO is pulled to the right in the figure to close the cold air intake passage 6. , warm air inside the warm air cover 5 is introduced into the upstream side of the air cleaner 2 through the warm air intake passage 7, and the warm air is introduced into the engine 1 through the warm air intake passage 7.
warm air is inhaled. and 1 hour after startup, e.g. 3
- Exhaust gas is recirculated from the diameter, and the exhaust gas flows into the intake air v3 via the exhaust gas recirculation control valve 12 and the exhaust gas recirculation passage 11. The amount of exhaust gas recirculated at this time is reversely controlled by the ECU 14 according to the engine speed and throttle position, and is set to an amount that does not deteriorate combustion under each engine condition. The reason for providing the time τ before exhaust gas recirculation is to prevent combustion deterioration and engine corrosion due to exhaust gas recirculation when the engine is cold.

The water temperature rises due to warm air intake and exhaust gas recirculation, and when the water temperature reaches a predetermined temperature of 80C, warm air intake and exhaust gas recirculation are stopped.

It is pointless to set this control temperature at 80C higher than the control temperature of a commonly used thermostat, 82C, so it is set at 80C, which is slightly lower than this temperature.

Thereafter, the water temperature is inversely controlled by the thermostat, and when it is necessary to reduce NOx in the exhaust gas, the exhaust gas recirculation is performed at a rate according to exhaust power regulations such as 10 mode.

As shown in FIG. 2, compared to the conventional water temperature rise (broken line), the warm-up time of this embodiment is longer.

Next, even after being sufficiently warmed up, the water temperature remains at the specified 80CK.
A case in which this is not achieved will be explained with reference to FIG. In such a case, use a heater and run at a low speed of 40 km/h in cold weather.
Easy to make noise when driving under low load. When the water temperature reaches 80C, warm air intake and exhaust recirculation are stopped. After that, the water temperature is detected after a certain period of time T1, for example, 3 minutes, and the temperature at this time is 8
When the temperature reaches 0c, negative pressure is introduced into the negative pressure chamber 8-a according to a command from the ECU 14, and warm air is sucked into the engine 1. At this time, the same effect can be obtained even if exhaust gas recirculation is performed instead of warm air intake, but this embodiment shows the case of warm air intake. When the water temperature rises and reaches a predetermined value of 80C, warm air intake is stopped. In this way, warm air is constantly introduced and stopped, and the water temperature is maintained at a predetermined temperature. Furthermore, if a predetermined water temperature is not reached after warm air intake has been carried out for a predetermined time T', for example, 5 minutes, a certain amount of exhaust gas is recirculated to raise the water temperature in advance, and then warm air intake is performed. By stopping, the water temperature is maintained at a predetermined temperature. This exhaust gas recirculation is performed by detecting the engine speed and throttle position (combustion injection amount) to ensure that the same amount of exhaust gas recirculation is always maintained within a range that does not affect combustion. In addition, by detecting the accelerator position, a constant accelerator opening (
(fuel injection amount), the ECU 14 stops exhaust gas recirculation and warm air intake.

Comparing the rise in water temperature according to this example with that of the conventional example, it can be seen that in the conventional example (broken line), the rise in water temperature is slow and low, but according to this example, the water temperature is maintained at a predetermined 80C.

Furthermore, in this embodiment, the warm air intake and exhaust gas recirculation are controlled by detecting the cooling water temperature, which allows the warm-up state of the engine to be ascertained, so that the control can be performed accurately in accordance with the warm-up state of the engine.

In addition, to accurately understand the warm-up state of the engine, check the oil temperature,
This can also be done by detecting the heater outlet air temperature, engine block wall temperature, etc.

Furthermore, in this embodiment, warm air intake and exhaust gas recirculation are used as a method for raising the water temperature, but in addition to this, intake throttling,
Possible causes include exhaust throttling, changing fuel injection timing, and insulating the engine intake system.

In tests conducted by the inventors, when warm air from exhaust heat or warm exhaust gas is inhaled into the engine, the overall working gas temperature rises, and not only does the water temperature rise rapidly, but also other gases. This method has the advantage that there is almost no deterioration in fuel efficiency compared to the above method. In fact, due to the intake of warm air and proper exhaust gas recirculation, the oil temperature rises, which reduces engine friction and even improves fuel efficiency. It has also been confirmed that exhaust heat is recovered by intake of warm air or exhaust air, and the heat is transferred to the cooling system.

By the way, under the above-mentioned 40km/H condition, by inhaling warm air, the intake gas temperature is about 30C lower than before.
The water temperature had risen by about 10C. Also, exhaust recirculation 3
At 0%, the intake gas temperature rose by about 70C and the water temperature rose by about 200C. In summary, the method of recovering warm air from exhaust heat, which was previously discarded to the outside, and of inhaling an appropriate amount of exhaust gas into the engine is a method for promoting warm-up of a diesel engine without deteriorating fuel efficiency. It turns out to be effective.

In this embodiment, the times such as τpT+*Tt are determined by finding appropriate values according to the engine specifications. Additionally, exhaust gas recirculation, which is performed 7 hours after engine startup, is set to an allowable exhaust recirculation rate that does not worsen combustion, but normally increasing this rate will cause CO2.

It is known that smoke, etc., can increase rapidly, so in this example, the allowable exhaust recirculation amount is set to an amount that does not cause a sudden increase in either Co or smoke, and the larger the exhaust recirculation amount, the higher the water temperature. The amount that is effective is determined by the engine rotation speed and the amount of fuel injection, and is controlled by the ECU 14. If the water temperature cannot be maintained at a predetermined level with only warm air intake, a certain amount of exhaust gas recirculation is performed, but in reality, the water temperature is examined and examined through engine tests, and it is necessary to check the The exhaust gas recirculation rate may be set to 30 cm.

Further, in this embodiment, the water temperature is used as a criterion for hot air intake and exhaust gas recirculation. Conventional warm air intake is done based on the intake air temperature, but if it is done based on the intake air temperature, there will be a temperature difference between the rise in the intake air temperature and the water temperature, and the engine warming will be stopped when the water temperature only reaches around 40C. For engines, it is more appropriate to switch the warm air intake based on the water temperature, oil temperature, etc., which can determine the warm-up state of the engine rather than the intake air temperature.

The relationship between the set water temperature, warm air, exhaust gas recirculation, and cold air in this embodiment is summarized as follows.

Below margin Preset temperature A second embodiment of the invention is shown in FIG.

This embodiment maintains the temperature of warm air as high as possible to further improve the effect of promoting engine warm-up.The difference from the first embodiment is that the outlet of the warm air intake passage to the intake pipe is placed on the downstream side of the air cleaner. The main feature is that the exhaust gas recirculation passage and the warm air intake passage have a double structure.

A vent pipe 7-'a branched from the intake W3 on the downstream side of the air cleaner 2 communicates with the sealed warm air cover 5, and an annular warm air intake passage 7b is formed around the exhaust recirculation passage 11 within the warm air cover 5. , and its discharge port is provided near the engine 1 in the intake pipe 3. As a result of adopting such a configuration, the cold FF13 switching valve 10, the actuator 8
, will be provided on the downstream side of the air cleaner 2.

Note that 15 is a heat insulating material provided outside the warm air intake passage 7-b. Fresh air taken in from the ventilation pipe 7-a is warmed in the warm air cover 5 and the warm air intake passage 7-b, and flows into the intake pipe 3 near the engine 1.

According to this embodiment, the temperature of the warm air is about 10 tons compared to the first embodiment.
When Z' increases and warm air intake and exhaust gas recirculation are performed at the same time, the increase will be about 15C compared to the first embodiment. In this way, this example is highly effective in increasing the intake gas temperature, but
On the other hand, since a closed warm air cover is used and a warm air passage around the exhaust gas recirculation passage is required, the cost is high.

In each of the above embodiments, the electromagnetic negative pressure switching valve 9 is used to switch the cooling/heating switching valve 10, but a thermostatic pressure switching valve (r<temperature sensing valve) may also be used.

As explained above, the present invention detects the warm-up state of the engine, and when the warm-up is insufficient, sucks air warmed by exhaust gas and recirculates the exhaust gas. Since the engine exhaust heat is utilized, the fuel efficiency is improved, and the exhaust gas recirculation provides a diesel engine warm-up device that complies with the υ exhaust gas regulations.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of the first embodiment of the present invention, Fig. 2 is a graph showing the relationship between cooling water temperature, exhaust gas recirculation amount, and warm air intake in the above embodiment, and Fig. 3 is a graph after warm-up in the above embodiment. A graph similar to FIG. 2 showing the operation when the cooling water temperature does not reach a predetermined temperature, and FIG. 4 is a system diagram of the second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Engine, 2... Air cleaner, 3... Intake pipe, 4... Exhaust manifold, 5... Warm air cover, 6... Cold air intake passage, 7... Warm air intake passage, 8・
... Actuator, 9... Negative pressure switching valve, 1o... Cooling/heating switching valve, 11... Exhaust recirculation passage, 12... Exhaust recirculation control valve, 13... Water temperature sensor, 14... ECU
.

Claims (1)

[Scope of Claims] 1. An exhaust gas recirculation passage for recirculating exhaust gas, an exhaust gas recirculation control valve installed in the exhaust gas recirculation passage for passing or blocking the exhaust gas, and a warm air valve for sucking warm air near the exhaust manifold. an intake passage, a cold air intake passage that takes in outside air, a cold/hot air switching valve that operates to shut off either the warm air intake passage or the cold air intake passage, and a detection mechanism that detects a warm-up state of the engine; It is equipped with a control circuit that controls an exhaust recirculation control valve and a cooling/heating air switching valve in conjunction with this detection mechanism,
A warming-up promoting device for a diesel engine that sucks in warm air and recirculates exhaust gas when the engine warms up to a predetermined condition. 2. The diesel engine warm-up promotion device according to claim 1, wherein the engine warm-up state detection mechanism is a cooling water temperature or oil temperature sensor. 3. The diesel engine warm-up promotion device according to claim 1, wherein when the warm-up of the engine reaches a predetermined condition, the intake of warm air and the recirculation of exhaust gas are stopped and cold air is sucked. 4. The diesel engine warm-up promotion device according to claim 1, wherein the amount of recirculation of the exhaust gas is an amount that complies with exhaust gas regulations. 5. The warming-up promoting device for a diesel engine according to claim 4, which stops the intake of warm air and continues the recirculation of exhaust gas if this state can be maintained after the warm-up of the engine reaches a predetermined condition. . 6. After the engine has warmed up to a predetermined condition and the intake of warm air and recirculation of exhaust gas are stopped, if the cooling water temperature falls below the predetermined temperature, either intake of warm air or recirculation of exhaust gas will be performed. A warming-up promoting device for a diesel engine according to claim 2. 7. After the warm-up of the engine reaches a predetermined condition and the intake of warm air and the recirculation of exhaust gas are stopped, if the cooling water temperature falls below a predetermined temperature, the intake of warm air and the recirculation of exhaust gas are simultaneously performed. A warm-up accelerating device for a diesel engine according to scope 2. 8. The diesel engine warm-up promotion device according to claim 1, which stops intake of warm air and recirculation of exhaust gas when the fuel injection amount is equal to or greater than a predetermined amount. 9. The diesel engine warm-up promotion device according to claim 1, wherein the discharge port of the warm air intake passage is provided on the lower side of the air cleaner in the intake passage. 10. The diesel engine warm-up promotion device according to claim 9, wherein the exhaust gas recirculation passage and the warm air intake passage have a double structure, and the inner passage is the exhaust recirculation passage and the outer passage is the warm air intake passage. .