JPH0513956Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a supercharging pressure regulating device for a supercharged engine.

[Prior Art] Various superchargers have been used in the past in order to improve engine output by increasing charging efficiency.
Among various types of superchargers, those that use the energy of exhaust gas to perform supercharging, such as exhaust turbo superchargers and complex pressure wave superchargers, Since the shaft output of the engine is not consumed by pressure, it has the advantage of improving both output and fuel efficiency.

In a supercharging system that performs supercharging using the energy of exhaust gas, a bypass exhaust passage is generally provided to bypass the turbocharger and pass the exhaust gas, and the opening and closing of this bypass exhaust passage is controlled. An on-off valve is provided, and the opening degree of the on-off valve is changed to adjust the flow rate of exhaust gas introduced into the supercharger, thereby controlling the supercharging pressure to a predetermined value. In order to drive the on-off valve, an actuator made of a positive pressure responsive rubber diaphragm is provided, and the supercharging pressure in the intake passage is generally used as the pressure source of this positive pressure.

However, such actuators are installed near the turbocharger body in order to improve the accuracy of the opening/closing position of the on-off valve or to make the turbocharging system more compact, so they do not absorb radiant heat from the high-temperature parts of the turbocharger. The temperature becomes high due to In addition, near the turbocharger body,
In some cases, the structure is covered with heat insulating material to prevent heat damage to the surrounding area or to prevent noise, which worsens the air flow around the actuator and rod, causing the actuator to become even hotter, e.g., reaching a maximum temperature of 191 to 234 degrees Celsius.
Sometimes it becomes. For this reason, the rubber inside the actuator is exposed to high temperatures, and the temperature of the rubber sometimes exceeds the permissible upper limit temperature (e.g. 150-180°C), which can damage the rubber and prevent the actuator from working properly. There was a problem that it may disappear. In response, the fuel supply amount is corrected according to the intake air temperature to suppress the rise in exhaust gas temperature and prevent heat damage to the exhaust system parts and surrounding parts. Although some methods have been proposed (for example, Japanese Patent Application Laid-Open No. 1983-
(Refer to Publication No. 138244), this had the problem that when the intake air temperature was high, the amount of fuel supplied was suppressed, resulting in a decrease in output and the effect of improving output due to supercharging was diminished.

On the other hand, the rubber inside the actuator hardens when the temperature drops below the allowable minimum temperature, so after starting the engine at extremely low temperatures, there was a problem where the actuator would not work properly due to the hardening of the rubber until the engine room warmed up. . In order to prevent this, a method of using rubber with excellent cold resistance may be considered, but on the other hand, rubber with excellent cold resistance has poor heat resistance (for example, the allowable temperature of cold resistant rubber is -25
On the other hand, rubber with excellent heat resistance has poor cold resistance (for example, the allowable temperature of heat-resistant rubber -
10 to 180℃), so it is not possible to simply use a rubber with excellent cold resistance.Also, even if a cold-resistant rubber is used, if the rubber temperature is lower than -25℃, There was a problem with the rubber hardening and the actuator not working properly.

[Purpose of the invention] The present invention has been made in view of the above-mentioned conventional problems, and is designed to prevent the rubber from being damaged even when the surrounding area of the actuator reaches high temperatures, and to protect the rubber from damage even when the temperature reaches extremely low temperatures. An object of the present invention is to provide a supercharging pressure adjustment device for a supercharged engine, which is equipped with an actuator that does not cause hardening and operates normally.

[Structure of the invention] In order to achieve the above-mentioned purpose, the invention includes a supercharger that supercharges intake air using the energy of exhaust gas;
A bypass exhaust passage that bypasses the supercharger and discharges exhaust gas, an on-off valve that controls opening and closing of the bypass exhaust passage, and a pressure chamber into which positive pressure of supercharging air is introduced, and the pressure in the pressure chamber is adjusted to the pressure inside the pressure chamber. In a supercharging pressure adjustment device for a supercharged engine, which is equipped with an actuator that opens and closes an on-off valve in accordance with the The machine is a complex pressure wave supercharger, and the first pressure introduction passage communicates the pressure chamber of the actuator with a position downstream of the supercharger and upstream of the intercooler in the intake passage, and a position downstream of the intercooler in the intake passage. Provided is a supercharging pressure adjustment device for a supercharged engine, characterized in that a second pressure introduction passage is provided that communicates the position of the actuator with the pressure chamber of the actuator.

[Effects of the invention] According to the invention, by utilizing the pressure difference before and after the intercooler in the intake passage, the supercharging air of the positive pressure source that operates the actuator is introduced at the first pressure from the intake passage on the upstream side of the intercooler where the pressure is high. In addition to introducing the supercharging air into the pressure chamber of the actuator through the passage, the supercharged air introduced into the pressure chamber is discharged through the second pressure introduction passage to the intake passage on the downstream side of the intercooler where the pressure is lower. is adiabatically compressed by the turbocharger and is hotter than the atmospheric temperature, but lower than the rubber's allowable upper limit temperature. It can be cooled to below the upper limit temperature, preventing damage to the cover due to overheating, and at the same time, at extremely low temperatures, the temperature inside the pressure chamber is raised, so the rubber can be heated to above the allowable lower limit temperature immediately after the engine starts, and the cover hardens quickly. As a result, the actuator can operate normally even at high temperatures or extremely low temperatures, and the reliability of the actuator can be greatly improved.

Furthermore, since the air drawn out from the intake passage and introduced into the pressure chamber of the actuator via the first pressure introduction passage is returned to the intake passage again via the second pressure introduction passage, there is an air flow meter upstream of the supercharger. is provided, no error is caused in the intake air amount detected by the air flow meter.

Additionally, in general, in a complex pressure wave supercharger, unlike an exhaust turbo supercharger, exhaust gas constantly enters the intake passage, so particles such as carbon in the exhaust gas enter the intake passage. Such carbon, etc. will be brought into the pressure chamber of the actuator, but according to the present invention, carbon, etc. is returned to the intake passage through the second pressure introduction passage, so carbon, etc. does not accumulate in the pressure chamber, and the deterioration of the diaphragm is prevented. This prevents this and increases the reliability of the actuator.

[Example] Hereinafter, embodiments of the present invention will be described in detail.

As shown in FIG. 1, the engine 1 includes a branch intake passage 4, which communicates with intake ports 3, 3, 3, 3 to supply intake air to the combustion chambers 2, 2, 2, 2.
4, 4, 4 are provided, and a common intake passage 5 is provided in communication with these branch intake passages 4, 4, 4, 4, while the combustion gas in the combustion chambers 2, 2, 2, 2 is Exhaust port 6, 6, for exhausting
Branch exhaust passages 7, 7, 7, 7 are provided in communication with 6, 6, and these branch exhaust passages 7,
A common exhaust passage 8 is provided in communication with 7, 7, 7.

A complex pressure wave supercharger 9 (hereinafter simply referred to as supercharger 9) is provided spanning both the common intake passage 5 and the common exhaust passage 8. This supercharger 9 has a large number of partition walls defined by a large number of vane-shaped partitions (not shown) radially arranged around a rotating shaft 12 rotatably held within a casing 11. A rotor 13 is provided with slot-like passages (not shown). The rotor 13 is rotationally driven by a crankshaft 15 of the engine 1 via a timing belt 14. With this rotation, each slit-like passage in the rotor 13
The exhaust side opening is the downstream part 8b of the common exhaust passage 8.
When it reaches the position where it communicates with the slit-shaped passage, the somewhat high-pressure exhaust gas trapped in the slit-shaped passage is released to the downstream part 8b of the common exhaust passage 8, generating an expansion wave, and immediately after this, the exhaust gas on the intake side of the slit-shaped passage When the opening communicates with the upstream portion 5a of the common intake passage 5, scavenging of exhaust gas and introduction of intake air are simultaneously performed within the slit-shaped passage due to the action of the expansion waves. Furthermore, the rotor 13 rotates, and the exhaust side opening of the slit-like passage communicates with the upstream portion 8a of the common exhaust passage 8, and the intake side opening communicates with the common intake passage 5.
When the exhaust gas reaches a position communicating with the downstream part 5b of the common exhaust passage 8, it is confined within the slit passage due to the action of compression waves generated by the high pressure exhaust gas flowing into the slit passage from the upstream part 8a of the common exhaust passage 8. The intake air that has been in use is pressurized and discharged to the downstream portion 5b of the common intake passage 5, so that the intake air is supercharged.

And downstream of the supercharger 9 in the common intake passage 5,
A water-cooled intercooler 16 is provided to cool the supercharged air which has been pressurized by the supercharger 9 and whose temperature has increased due to the adiabatic compression effect, and prevents a decrease in intake air density due to a rise in intake air temperature, thereby improving charging efficiency. I'm trying to increase that.

On the other hand, in order to adjust the amount of exhaust gas introduced into the supercharger 9 and control the supercharging pressure to a predetermined value, the supercharger 9 is bypassed and the common exhaust passage 8 is placed upstream of the supercharger 9. A bypass exhaust passage 21 is provided that communicates the branching part 18 located there with the merging part 19 located downstream of the supercharger 9.
1 is provided with an on-off valve 22 that controls opening and closing of the bypass exhaust passage 21 near the branch portion 18. This on-off valve 22 is provided with an actuator 24 made of a positive pressure responsive rubber diaphragm 23 .

As shown in FIG. 2, the space defined inside by the housing 25 of the actuator 24 is maintained at approximately atmospheric pressure by the rubber diaphragm 23 and the pressure chamber 26 into which positive pressure is introduced. It is partitioned into a normal pressure chamber 27 and a normal pressure chamber 27. The diaphragm 23 is always urged rearward (rightward in FIG. 2) by a coil spring 28 provided in the normal pressure chamber 27, and the positive pressure introduced into the pressure chamber 26 is maintained at a predetermined value. In the following cases, the diaphragm 23 is retracted to the rearmost position by the coil spring 28, and at this time the on-off valve 22 (see FIG. 1) is connected to the diaphragm 23 via a connecting rod 29.
is becoming closed. In addition, pressure chamber 2
When positive pressure exceeding a predetermined value is introduced into 6,
Depending on the magnitude of the positive pressure, the diaphragm 23 is moved forward against the biasing force of the coil spring 28, and the on-off valve 22 (see FIG. 1) is correspondingly opened. As a result, when the supercharging pressure is higher than the set value, exhaust gas is discharged through the bypass exhaust passage 21 (see Fig. 1), bypassing the supercharger 9 (see Fig. 1) according to the deviation. , the boost pressure is maintained at a set value.

As shown again in FIG.
In order to introduce positive pressure for operating the actuator 24 into the pressure chamber 26 of the common intake passage 5, the first communication portion 31 located downstream of the supercharger 9 and upstream of the intercooler 16 communicates with the pressure chamber 26. A first pressure introduction passage 32 is provided to communicate with the pressure chamber 26 and a second communication portion 33 located downstream of the intercooler 16 in the common intake passage 5 is provided. Then, as will be explained in detail later, the supercharged intake air is transferred to the pressure chamber 2.
6, the diaphragm 2
In order to prevent the rubber forming the pressure chamber 3 from hardening due to overheating or low temperatures, the first pressure introduction passage 32 is connected to the periphery of the rear surface of the pressure chamber 26 in order to improve the circulation of intake air within the pressure chamber 26. On the other hand, the second pressure introduction passage 34 is connected to the side surface of the pressure chamber 26 at a position as far away as possible from the connection between the first pressure introduction passage 32 and the pressure chamber 26 .

Hereinafter, the functions of the first pressure introduction passage 32 and the second pressure introduction passage 34 will be explained in detail.

The intake air pressurized by the supercharger 9 is transferred to the intercooler 1
6, a pressure loss occurs due to the flow resistance of the intercooler 19, and this pressure loss reaches a maximum near the rated output point, for example, and becomes about 40 mmHg.
Therefore, a pressure difference corresponding to the pressure loss described above occurs between the first communication section 31 and the second communication section 33 of the common intake passage 5, so that a part of the intake air is transferred from the first communication section 31 to the second communication section 33. Sequentially, the first pressure introduction passage 32, the pressure chamber 26, and the second pressure introduction passage 34 are indicated by arrows A ₁ , A ₂ ,
The supercharged air flows to the second communication portion 33 through paths as shown by A ₃ , A ₄ , A ₅ , and A ₆ (hereinafter, supercharged air flowing through such paths is referred to as bypass intake air). At this time, the characteristics of the pressure of the supercharging air in the first communication part 31 and the second communication part 33 with respect to the engine rotation speed are as follows.
As shown in curves G ₁ and G ₂ in FIG. 3, respectively.
The operating pressure of the actuator 24 applied to the pressure chamber 26 becomes a curve _G3 that is approximately halfway between the curve _G1 and the curve _G2 . Similarly, the characteristics of the pressure of supercharging air in the first communication portion 31 and the second communication portion 33 with respect to the engine load are expressed by the curves G 4 _{and 4} in FIG. 4, respectively.
Shown as _G5 . The operating pressure of the actuator 24 applied to the pressure chamber 26 is as shown by curve _G6 .

Since the temperature of the bypass intake air is adiabatically compressed by the supercharger 9, for example, when the outside temperature is 25°C, the temperature will be 50 to 140°C, which is 25 to 115°C higher than the outside temperature. Of course, the temperature of the intake air is also rising.) Therefore,
If this bypass intake air flows in the pressure chamber 26 and the temperature of the actuator 24 exceeds the rubber's allowable upper limit temperature of 150 to 180°C, the rubber will be lowered to below the allowable upper limit temperature by the bypass intake air. On the other hand, if the outside temperature is below the rubber's allowable minimum temperature (-25 to -10°C), the rubber will quickly warm up to the allowable minimum temperature or higher.
Deterioration in the operability of the actuator 24 due to overheating damage or low temperature hardening of the rubber can be reliably prevented. Note that normally, the higher the engine load or engine speed, the greater the thermal load on the actuator 24, and the stronger the cooling is required.
More bypass intake air is required, but in this operating state of the engine 1, the amount of intake air increases, so the pressure loss at the intercooler 16 also increases (under turbulent flow, the pressure loss is proportional to the square of the intake flow rate). ) Bypass intake air flow increases and sufficient cooling is achieved.

In this way, the flow rate of the bypass intake air required to maintain the rubber of the actuator 24 within the permissible temperature range regardless of temperature conditions is estimated to be a maximum of approximately 100/min, and this amount is 1% of the total intake air volume. It is as follows. At this time, part of the intake air is transferred to the intercooler 16
The decrease in output due to the increase in intake temperature caused by supplying the combustion chambers 2, 2, 2, 2 without cooling is
It is estimated to be less than 0.05%, which is practically negligible.

In addition, it is possible that the intake pulsation in the common intake passage 5 may have some influence on the operation of the actuator 24, but the frequency of the intake pulsation (around 100Hz)
is significantly different from the natural frequency of the actuator 24 (approximately 1000Hz), and the intake pulsation is
Inside the pressure introduction passage 32 or the second pressure introduction passage 3
4, the intake pulsation does not interfere with the operation of the actuator 24.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of an engine equipped with a complex type pressure wave supercharger, showing an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional explanatory diagram of the actuator shown in FIG. 1. FIG. 3 is a diagram showing the characteristics of boost pressure with respect to engine speed. FIG. 4 is a diagram showing the characteristics of boost pressure with respect to engine load. 1...Engine, 5...Common intake passage, 8...
Common exhaust passage, 9...supercharger (complex type), 16...intercooler, 21...bypass exhaust passage, 22...on/off valve, 24...actuator, 26...pressure chamber, 32...first Pressure introduction passage, 34...second pressure introduction passage.

Claims (1)

[Scope of claim for utility model registration] A supercharger that supercharges intake air using the energy of exhaust gas, a bypass exhaust passage that bypasses the supercharger and discharges exhaust gas, and opens and closes the bypass exhaust passage. an on-off valve to be controlled; an actuator that includes a pressure chamber into which positive pressure of supercharging air is introduced; and an actuator that opens and closes the on-off valve according to the pressure in the pressure chamber; In a supercharging pressure adjustment device for a supercharged engine equipped with an intercooler for cooling charge air, the supercharger is a complex pressure wave supercharger, and the supercharger is located downstream of the supercharger and upstream of the intercooler in the intake passage. A first pressure introduction passage that communicates between a position in the intake passage and a pressure chamber of the actuator, and a second pressure introduction passage that communicates a position downstream of the intercooler in the intake passage and the pressure chamber of the actuator are provided. Boost pressure adjustment device for supercharged engines.