JPS647224Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device for controlling boost pressure in a diesel engine equipped with a supercharger according to engine heat load.

(Prior art) Generally, diesel engines equipped with a supercharger to increase the amount of intake air output power by increasing the fuel injection amount according to the boost pressure, as shown in Figure 1. I'm getting excited.

To explain this, in the figure, 1 is the engine body, 2 is an intake passage, and 3 is an exhaust passage.
A compressor 6 is interposed in the intake passage 2, and a turbine 5 rotated by exhaust pressure drives the compressor 6 coaxially with the compressor 6 to forcefully feed intake air to the engine body (combustion chamber) 1.

Then, the supercharging pressure in the intake passage 2 (compressor 6
downstream pressure) is guided to the boost compensator (not shown) of the fuel injection pump 8 via the pressure passage 7, and as shown in FIG. is increasing.

As a result, more air and fuel are supplied to the engine body 1 than in the case without a supercharger, and the engine output is improved.

In addition, numeral 9 in the figure is a waste gate valve that allows a part of the exhaust gas to flow into the bypass passage 10 of the turbine 5 when the boost pressure exceeds a predetermined upper limit value.

(Problem that the invention aims to solve) However, in the case of such a supercharged internal combustion engine, the fuel injection amount increases when the supercharging pressure is high, so the supercharging pressure temporarily exceeds the upper limit. Even if the wastegate valve 9 opens to lower the boost pressure in such a case, if the operating state near the point just before the wastegate valve 9 opens for a long period of time continues, the heat load on the engine will become extremely large. In the worst case scenario, the engine could overheat and the piston could seize.

In response, the present applicant has proposed a device that suppresses the amount of fuel by introducing high pressure to the boost compensator to counteract the supercharging pressure at high temperatures (Utility Model Application No. 55-158223). (see official bulletin),
This device requires a high-pressure tank to supply high pressure, making it difficult to apply to passenger cars, etc., and requires structural precision as it is necessary to maintain an appropriate balance between tank pressure and boost pressure. I felt a hatred for him.

The present invention aims to solve these problems.

(Means for solving the problem) In order to achieve the above object, the present invention provides an internal combustion engine equipped with a supercharger that supercharges engine intake air and a boost compensator that increases the amount of fuel supplied according to boost pressure. In an engine, the boost pressure is forcibly reduced by reducing the pressure led to the boost compensator through a means for detecting the engine temperature and a three-way solenoid valve that switches and operates when the detected temperature exceeds a predetermined upper limit. The means for forcibly lowering the boost pressure includes a throttle valve located in the middle of the path for introducing boost pressure into the boost compensator, and a throttle valve that reduces the opening degree of the throttle valve when negative pressure is introduced. The vacuum actuator is equipped with a vacuum actuator to actuate the vacuum actuator, and an engine-driven vacuum pump that drives the vacuum actuator. It was configured to supply to Yueta.

(Function) In the above configuration, when the engine temperature exceeds a predetermined upper limit value, the three-way solenoid valve is switched, and the vacuum actuator is driven in a direction to close the throttle valve in the intake passage. Therefore, the supercharging pressure supplied to the engine is throttled and the amount of intake air is reduced, and fuel increase control by the boost compensator is also suppressed, so the amount of heat generated by the engine, that is, the heat load, is reduced.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. Note that parts corresponding to those in FIG. 1 are designated by the same reference numerals as in the same figure.

In FIG. 3, a throttle valve 15 is interposed in the middle of the intake passage 2 so as to be located upstream of the inlet of the pressure passage 7 that guides supercharging pressure to the boost compensator of the fuel injection pump 8. .

A vacuum actuator 16 is connected to this throttle valve 15 as its driving means, and a vacuum actuator 16 receives negative pressure from a vacuum pump 18 via a three-way solenoid valve 19 into a negative pressure chamber 17 of the vacuum actuator 16. Or atmospheric pressure is selectively introduced.

The three-way solenoid valve 19 is energized from the power source 13 by turning on and off a temperature switch 12 as a temperature detection means, and when the engine cooling water temperature exceeds a set value, the temperature switch 12 is turned on and the negative pressure is vacuum actuated. It is introduced into the Yueta 16. At this time,
Vacuum actuator 16 drives throttle valve 15 in a direction to narrow down the passage area of intake passage 2. On the other hand, when the cooling water temperature is below the set value, the temperature switch 12 is turned on, and accordingly, the three-way solenoid valve 19
introduces atmospheric pressure into the vacuum actuator 16. In this state, the throttle valve 15 is positioned at the fully open position.

Therefore, in an operating region where the engine cooling water temperature is below the set value and the thermal load is relatively small, the supercharging pressure in the intake passage 2 is directly supplied to the boost compensator of the fuel injection pump 8 via the pressure passage 7. Therefore, as shown in FIG. 4, the fuel injection amount and engine output increase in accordance with the boost pressure.

On the other hand, when the heat load of the engine increases and the cooling water temperature exceeds the set value of the temperature switch 12, the three-way solenoid valve 19 switches to apply negative pressure from the vacuum pump 18 to the vacuum actuator 16. The throttle valve 15 is driven in the closing direction to introduce
The intake passage 2 is narrowed. This reduces the boost pressure, i.e. the air flow supplied to the engine, and
Since the pressure supplied to the boost compensator of the fuel injection pump 8 via the pressure passage 7 located downstream of the throttle valve 15 also decreases, the fuel injection amount and engine output decrease. At this time, not only the fuel injection amount but also the supercharging pressure is forcibly reduced based on the closing operation of the throttle valve 15, so the amount of heat generated by the engine is quickly and responsively reduced in accordance with the operation of the temperature switch 12. Ru.

In this way, the thermal load is reduced when the engine approaches its thermal endurance limit, thereby quickly and reliably avoiding problems such as overheating and piston seizure.

(Effects of the invention) As described above, the present invention reduces the boost pressure when the engine heat load exceeds the upper limit, so it is possible to quickly reduce the heat load and avoid engine overheating and piston seizure. I can do it. In particular, in the present invention, since the boost pressure itself in the intake passage is reduced by the throttle valve, the thermal load during high-load operation can be effectively reduced in a responsive manner.

In addition, the present invention reduces the supercharging pressure to the boost compensator by driving the throttle valve by switching the pressure via the three-way solenoid valve, so the structure is relatively simple and reliable. Moreover, it is also applicable to vehicles that are not equipped with a high-pressure tank.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional example, and FIG. 2 is a diagram of its operating characteristics. FIG. 3 is a sectional view of an embodiment of the present invention, and FIG. 4 is a diagram showing its operating characteristics. 2... Intake passage, 3... Exhaust passage, 4... Turbocharger, 7... Pressure passage, 8...
...Fuel injection pump, 12...Temperature switch, 15
... Throttle valve, 16 ... Vacuum actuator, 19 ... Three-way solenoid valve.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine equipped with a boost compensator that increases the amount of fuel supplied in accordance with boost pressure along with a supercharger that supercharges engine intake air, there is provided a means for detecting engine temperature, and a means for detecting engine temperature when the detected temperature exceeds a predetermined upper limit value. means for forcibly lowering the boost pressure by reducing the pressure guided to the boost compensator via a three-way solenoid valve that switches and operates when the A throttle valve located in the middle of the path that introduces supply pressure to the boost compensator, a vacuum actuator that reduces the opening of this throttle valve when negative pressure is introduced, and an engine drive that drives this vacuum actuator. a vacuum pump, and is configured to selectively supply negative pressure or atmospheric pressure from the vacuum pump to the vacuum actuator via a three-way solenoid valve. .