JPH0531240Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to a control device for a supercharged engine installed in an automobile or the like.

(B) Prior Art For example, in the case of a supercharged engine equipped with a carburetor, supercharging pressure acts within the intake pipe, so in the operating range where the pressure is high, fuel does not flow out from the carburetor float chamber. Become. Further, even when the supercharging pressure suddenly rises, such as during sudden acceleration, the followability of the fuel is poor and the mixture tends to become lean. Therefore, in order to improve the output characteristics in the high load range and further improve acceleration performance, etc., it is desirable to supply additional fuel into the intake system passage in the above-mentioned operating range.

By the way, Japanese Patent Laid-Open No. 146038/1983 discloses a prior art related to a device that adds fuel into the intake system in a predetermined operating range. In other words, this device has a single pressure switch that closes when the downstream side of the throttle valve in the intake system becomes positive pressure, and a base end connected to the discharge port of the fuel pump and a tip connected to the intake system path. and a normally closed solenoid valve that is interposed in the middle of the additional fuel passage and opens the additional fuel passage when the pressure switch is closed. Additional fuel can be supplied to the intake line when opened. By the way, this device controls the supply of additional fuel by opening and closing a solenoid valve by switching a single pressure switch, so if the pressure switch malfunctions, it may become impossible to supply additional fuel. , it becomes impossible to stop the supply. Moreover, this pressure switch
Since the pressure switch is set to close when the downstream side of the throttle valve becomes positive pressure and issue a command to supply fuel, the pressure switch is closed very often while the vehicle is operating. Therefore, there is a high possibility that this pressure switch will fail on the closed side and the additional fuel will continue to be supplied. Therefore, the pressure switch may become locked in the closed position due to a failure even when the vehicle is driving in a city area where supercharging is not required much. If this happens, too much fuel will be supplied inappropriately and the air-fuel mixture will become too rich, causing the engine speed to rise inappropriately, causing the vehicle to jump out when the clutch is engaged, and causing the exhaust system to overheat and damage the catalyst. There is a risk. Furthermore, fuel consumption also deteriorates.

(C) Purpose The present invention was developed with an eye on the above situation, and it is possible to improve output characteristics and acceleration performance by adding fuel at necessary times, and it also makes it possible to improve output characteristics and acceleration performance in the event of a pressure switch failure. An object of the present invention is to provide a control device for a supercharged engine that can minimize the risk of additional fuel being supplied at an unnecessary time.

(D) Structure In order to achieve the above object, the present invention provides a system for independently switching to the supply command position when the pressure at a predetermined position in the intake system path equipped with a supercharger exceeds each set pressure. A pair of pressure switches that switch between the pressure switches and a fuel addition means that supplies additional fuel into the intake system passage when both pressure switches are switched to the supply command position are provided. The set pressure of the other pressure switch is set higher than the set pressure of the pressure switch, and the set pressure of the other pressure switch is set to correspond to the pressure in the intake system when supercharging is substantially started. and,
Both pressure switches are operated by pressure downstream of the throttle valve or by pressure upstream of the throttle valve.

(E) Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 (Fig. 1, Fig. 2) Fig. 1 is a system explanatory diagram of an engine control device according to the present invention, in which 1 is an engine main body, 2
3 is an intake system path, and 3 is an exhaust system path. The intake system passage 2 is for guiding air taken in through an air cleaner (not shown) to the intake port 1a of the engine main body 1, and a compressor section 5, a surge tank 6, and a carburetor 7 of the turbocharger 4 are sequentially installed on the way. It has been intervened. Further, the exhaust system path 3 is for discharging exhaust gas discharged from the exhaust port 1b of the engine body 1 into the atmosphere via a catalytic converter and a muffler (not shown). Section 8 is provided. Further, a bypass passage 9 is provided in parallel to the turbine section 8 of the exhaust system passage 3, and a waste gate valve 10 is interposed in the bypass passage 9. The waste gate valve 10 is equipped with a diaphragm mechanism 10a that is activated by the pressure in the intake system passage 2, and as shown in _FIG .
It is designed to open and close in such a way that the temperature does not exceed

A pair of pressure switches 11 and 12 and a fuel adding means 13 are connected to the intake system path 2.
and. One pressure switch 11 has its diaphragm chamber 11a communicated with the downstream side of the throttle valve 14 of the carburetor 7 of the intake system path 2, and the pressure on the downstream side is set to the first set pressure _S1.
(for example, +200 mmHg), the supply command position, that is, the movable contact 11c held by the diaphragm 11b contacts the fixed contact 11d.
It is designed to switch to the ON position. Further, the other pressure switch 12 has its diaphragm chamber 1
2a is connected to the downstream side of the throttle valve 14, and the pressure on the downstream side is the second set pressure.
S ₂ (for example, +50 mmHg), the supply command position, that is, the movable contact 12c held by the diaphragm 12b contacts the fixed contact 12d.
It is designed to switch to the ON position. Note that the second set pressure _S2 is determined in accordance with the pressure within the intake system path 2 when supercharging is substantially started. Further, the fuel adding means 13 is configured to be able to supply additional fuel into the intake system path 2 when both the pressure switches 11 and 12 are switched to the supply command position, and specifically, Connect the base end to the fuel pump 1
The fuel passage 17 is connected to the discharge port 15a of the surge tank 6 and has the other end facing into the surge tank 6 through a fuel injection nozzle 16, and a switching valve 18 interposed in the middle of the fuel passage 17. There is. The switching valve 18 is configured to switch to a position where the fuel passage 17 is opened when the input terminal 18a is energized, and return to a position where the fuel passage 17 is closed when the energization is cut off. The input terminal 18a is connected to a power source 22 through a normally open contact 19a of a first relay 19 and a normally open contact 21a of a second relay 21 in series. Then, the excitation coil 19b of the first relay 19 is connected to the power source 23 via the first pressure switch 11, and
The excitation coil 21b of the second relay 21 is connected to the power source 23 via the second pressure switch 12. Note that 24 is a turbo indicator, and this turbo indicator 24 is connected to 22 via the normally open contact 21a of the second relay 21.

With such a configuration, both the first and second pressure switches 11 and 12 are maintained in the OFF state in a region where the engine speed is low and supercharging is not sufficiently performed. The switching valve 18 is held in the cutoff position, no additional fuel is supplied, and the turbo indicator 24 is off. From this state, the rotational speed of the engine gradually increases, and when substantial supercharging starts and the pressure on the downstream side of the throttle valve 14 exceeds the second set pressure S2 mentioned above, the second set pressure _S2 is increased. The pressure switch 12 switches to the ON state, and the second relay 21
is excited and the turbo indicator 24 lights up,
Displays that supercharging has started. From this state,
When the rotational speed of the engine becomes higher and the pressure on the downstream side of the throttle valve 14 exceeds the first set pressure _S1 mentioned above, the first pressure switch 11 also switches on.
Switches to ON state. As a result, both relays 19,
Both the normally open contacts 19a and 21a of 21 become conductive, and the input terminal 18a of the switching valve 18 is energized to open the valve 18. Therefore, additional fuel from the pump 15 is guided through the fuel passage 17 to the fuel injection nozzle 16 and is injected into the surge tank 5 via the nozzle 16 . Therefore,
Undue dilution of the air-fuel mixture in a high load range (the operating range indicated by diagonal lines A in FIG. 2) is prevented, and output characteristics and acceleration performance are improved.

In this way, additional fuel is supplied into the intake system path 2 in the necessary region, but in the case of the present invention, the pressure switches 11 and 12, which form a pair, must both be switched to the supply command position. Since fuel cannot be supplied, pressure switch 1
The probability that a failure of 1 or 12 will result in an undue supply of fuel is much lower than with a single pressure switch. Moreover, since the set pressure S ₁ of one pressure switch 11 is set higher than the set pressure S ₂ of the other pressure switch 12, the pressure switch 11, 12 are not frequently switched to the supply command position at the same time, and the lower set pressure
S ₂ is also set to a high value corresponding to the pressure when supercharging actually starts, so compared to using a switch with a low set pressure that switches when positive pressure is applied, if the first Even if the pressure switch 11 is normally closed and malfunctions, the pressure switch 11, 1
2 is switched to the supply command position less frequently. Therefore, a malfunction in which the pressure switches 11 and 12 stop and stop moving at the supply command position is less likely to occur. Therefore, this kind of system can effectively prevent the inconvenience of fuel being inappropriately supplied due to a malfunction of the pressure switch in areas where additional fuel supply is not required, such as in urban driving areas. This effectively eliminates the dangers of engine braking becoming less effective, overheating the exhaust system, and damaging the catalyst. In addition, if this is the case, the setting pressure _S1 of the first pressure switch 11 may be set freely to determine the area A to which fuel should be added, but the setting pressure S1 of the second pressure switch 12 may be set freely. Since the pressure _S2 is set to the value when supercharging has actually started, this second pressure switch 12 is used to turn on the turbo indicator 24 to notify that supercharging has started. It can also be used as a signal transmitting means. Conversely, it is also possible to use an existing pressure switch for lighting a turbo indicator or the like as the second pressure switch 12 of the present invention.

Embodiment 2 (Fig. 3) This Embodiment 2 is obtained by adding some circuits to the above-mentioned Embodiment 1, and parts that are the same as or corresponding to those of the above-mentioned Embodiment 1 are given the same symbols and explained. Omitted.

In this embodiment, a recirculation passage 25 for recirculating exhaust gas is provided between the exhaust system passage 3 and the intake system passage 2, and a negative pressure type recirculation control valve 26 is interposed in the middle of this recirculation passage 25. There is. The diaphragm chamber 26a of this reflux control valve 26 and the vaporization chamber 6
A three-way valve 28 is interposed in the middle of the negative pressure introduction path 27 that connects with the EGR port 7a. The three-way valve 28 has a first port a communicating with the diaphragm chamber 26a.
, a second port b communicating with the EGR port 7a, and a third port c open to the atmosphere, and when the input terminal 28a is energized, the first port a and the third port c are connected. The first port a and the second port b are brought into communication when the current is turned off. Then, the input terminal 2
8a to the power supply 23 via the second pressure switch 12.
I'm connected to In addition, the normally closed contact 19c of the first relay 11 and the second
A safety circuit 29 is provided in which the normally open contact 21a' of the relay 21 is connected in parallel.

With such a configuration, basically the same effects as in the first embodiment can be obtained. Further, while the EGR port 7a of the carburetor 7 is under negative pressure, the power to the three-way valve 28 is cut off, so the diaphragm chamber 26a of the reflux control valve 26 is
It is connected to the EGR port 7a, and exhaust gas is recirculated as usual. However, when the rotational speed of the engine increases and supercharging is substantially started and the second pressure switch 12 is switched to the ON state,
The input terminal 28a of the three-way valve 28 is also energized, and the diaphragm chamber 26a of the recirculation control valve 26 is opened to the atmosphere. Therefore, the recirculation of exhaust gas is stopped. By doing so, high positive pressure due to supercharging is not applied to the diaphragm chamber 26a, so that the durability of the diaphragm 26b can be improved. That is, if negative pressure and positive pressure are repeatedly applied to the diaphragm chamber 26a, the diaphragm 26b will be inverted each time, and the durability of the diaphragm 26b will be significantly deteriorated, but according to this embodiment, Such inconvenience can be prevented. Furthermore, in this embodiment, the safety circuit 2
9, the second pressure switch 12
ON, and then the first pressure switch 11
Additional fuel will not be supplied unless it is turned ON. That is, if the first pressure switch 11 is normally closed and fails, in the first embodiment, fuel injection is performed from the time when the second pressure switch, which has a lower set pressure, is turned on. In other words, in Example 1, emphasis is placed on reducing as much as possible the possibility of erroneous fuel injection in the non-supercharged region, which accounts for the majority of city driving, and as mentioned above, the has achieved its purpose. However, in this second embodiment, the first pressure switch 11 is
If a failure occurs in the ON position, the exciting current continues to flow through the first relay 19, and the normally closed contact 19c of the first relay 19 remains open. Therefore, even if the second pressure switch 12 is turned on, no current flows to the second relay 21, and fuel injection is not performed. Moreover, in this way, the first pressure switch 11
In a dangerous situation, such as when a failure occurs in the ON position, the turbo indicator 24 will not light up even if the turbo is activated, which can contribute to early detection of failure. There are also other ways in which the pressure switch may malfunction.
It is possible that the pressure switch 12 becomes locked in the OFF position or that the second pressure switch 12 stops in the ON or OFF position, but if the first pressure switch 11 fails in the OFF position, the fuel injection is not performed. There is no danger as it will only prevent the damage from occurring. Also,
A failure of the second pressure switch 12 does not cause a major problem because the fuel addition timing is determined by the first pressure switch 11. Therefore, according to this second embodiment, safety can be further improved than that of the first embodiment.

In each of the above embodiments, a case has been described in which both pressure switches are operated by the pressure on the downstream side of the carburetor throttle valve, but the present invention is not necessarily limited to such a configuration. For example, both pressure switches may be operated by pressure upstream of the throttle valve.

(F) Effect Since the present invention has the above-mentioned configuration, it is possible to improve output characteristics and acceleration performance by adding fuel at necessary times, and moreover, it is possible to improve output characteristics and acceleration performance by adding fuel at necessary times. The risk of being supplied at an unnecessary time can be minimized, and furthermore, a signal indicating whether or not supercharging has started can be easily extracted and used for appropriate control such as lighting an indicator. Accordingly, it is possible to provide a control device for a supercharged engine that can perform the following steps.

In addition, in the present invention, both pressure switches are operated by pressure on the downstream side of the throttle valve, or
Since the throttle valve is actuated by the pressure on the upstream side of the throttle valve, it is also possible to set the operating pressures of both pressure switches relatively easily. That is, the relationship between the pressure on the downstream side and the pressure on the upstream side of the throttle valve varies in various ways depending on the engine speed, the opening degree of the throttle valve, and the like. Therefore, when one pressure switch is connected to the downstream side and the other pressure switch is connected to the upstream side, all operating conditions must be verified in order to specify a constant switching priority between both pressure switches. It takes time and effort to set the operating pressure value of each pressure switch. On the contrary,
When both pressure switches are connected to the downstream side of the throttle valve, or when both pressure switches are connected to the upstream side, as in the invention of the present invention, the pressure acting on both pressure switches changes depending on the engine speed and the throttle valve. With changes in the opening degree of the valve, etc., the values increase and decrease with the same tendency. Therefore, the operating pressures of both pressure switches can be set relatively easily without complicated verification of pressure fluctuations in various operating ranges. This ensures that the purpose of minimizing the risk of additional fuel being supplied at an unnecessary time due to switch failure can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a system explanatory diagram showing one embodiment of the present invention, FIG. 2 is a characteristic diagram of the same embodiment, and FIG. 3 is a system explanatory diagram showing another embodiment of the present invention. 2... Intake system path, 4... Supercharger, 11... Pressure switch, 12... Pressure switch, 13... Fuel addition means.

Claims (1)

[Scope of utility model registration request] A pair of pressure switches that independently switch to the supply command position when the pressure at a predetermined position in the intake system path equipped with the turbocharger exceeds each set pressure, and both pressure switches switch to the supply command position. and a fuel adding means for supplying additional fuel into the intake system passage when the pressure switch is switched to the intake system, and the set pressure of one pressure switch is set higher than the set pressure of the other pressure switch. The set pressure of the other pressure switch is determined to correspond to the pressure in the intake system passage when supercharging is substantially started, and both pressure switches are set on the downstream side of the throttle valve. 1. A control device for a supercharged engine, characterized in that the control device is operated by pressure on the upstream side of a throttle valve or by pressure on the upstream side of a throttle valve.