JPH07116951B2 - Intake device for engine with mechanical supercharger - Google Patents

Description

TECHNICAL FIELD The present invention relates to an intake device for an engine including a mechanical supercharger such as a vane pump or a roots blower.

[Prior Art and Its Problems] Conventionally, a mechanical supercharger driven by an engine output shaft is provided, and by charging intake air to supply it to the engine, filling efficiency is increased to achieve higher output. Engines with mechanical superchargers are well known (see Japanese Patent Laid-Open No. 61-19930).

Since this type of mechanical supercharger is driven by the engine output shaft, supercharging pressure characteristics that are proportional to the engine speed are obtained, and it is more responsive than a turbocharger that is driven by engine exhaust gas. While there are excellent advantages, such advantages themselves entail the following drawbacks.

That is, when traveling in a low speed gear, the change in the engine speed is large with respect to the change in the vehicle speed, and the rotation fluctuation directly changes the rotation of the supercharger, and the durability of the rotation system such as the oil seal and the drive belt is increased. It also adversely affects sex. Further, when air is supplied from the air discharge port of the supercharger (when the discharge port is open), a force is applied to the rotating shaft of the supercharger due to the supercharging pressure in the intake passage downstream of the supercharger, and the shaft bends. However, this bending causes wear. Furthermore, during low-speed traveling, since there is little traveling wind, the mechanical supercharger cannot be cooled sufficiently, and the amount of heat generated due to wear also increases, which reduces the reliability of the mechanical supercharger. There's a problem.

[Object of the Invention] The present invention has been made in view of the problems of the mechanical supercharger as described above, and effectively protects the mechanical supercharger during low-speed gear running to improve its reliability. The purpose is to improve.

Therefore, according to the present invention, in an engine having a mechanical supercharger driven by an engine output shaft in an intake passage, a shift position detecting means for detecting a shift position of a transmission and a shift position detecting means. And a supercharging pressure control means for controlling the supercharging pressure to be lowered as the gear shift position is on the lower speed side, and an intake device for an engine with a mechanical supercharger. Thus, during low speed gear running, the supercharging pressure itself is lowered so that excessive pressure fluctuations due to rotational fluctuations will not occur in the mechanical supercharger.

[Effects of the Invention] According to the present invention, therefore, the mechanical supercharger can be effectively protected during low-speed gear travel, and the reliability of the mechanical supercharger can be improved.

[Examples] Hereinafter, examples of the present invention will be specifically described with reference to the accompanying drawings.

As shown in FIG. 1, in an intake passage 2 of an engine 1, a vane pump 7 as a mechanical supercharger is connected to a drive pulley 5 driven by a belt 4 by an engine output shaft 3 via an electromagnetic clutch 6. When the electromagnetic clutch 6 is turned on, the vane pump 7 is driven to pressurize the intake air and supply it to the combustion chamber 8 of the engine 1.

An air flow meter 11 for detecting the momentary intake air amount is provided immediately below the air cleaner 9 in the intake passage 2, and an access pedal (not shown) is provided further downstream thereof.
A throttle valve 12 that opens and closes in conjunction with the depression of the vane pump 7 is provided, and the vane pump 7 is provided downstream of the vane pump 7.
A surge tank 13 that temporarily stores the intake air pressurized by is provided, and a fuel injection valve 16 is provided toward an intake port 15 that is opened and closed by an intake valve 14.

With respect to the vane pump 7, a surge tank is bypassed from the intake passage 2 downstream of the throttle valve 12 by bypassing the vane pump 7.
A bypass air passage 17 reaching 13 is provided, and a relief valve 19 which is opened and closed by a diaphragm type actuator 18 is provided in the middle of the bypass air passage 17 to communicate or block the bypass air passage 17.

This diaphragm actuator 18 has a relief valve 19
The relief valve 1 of the bypass air passage 17 in the pressure chamber 18b partitioned by the diaphragm 18a that supports the
9. A negative pressure introducing passage 20 having a negative pressure outlet on the upstream side of 9 and an atmospheric pressure introducing passage 21 whose one end is open to the atmosphere are communicated with each other, and the negative pressure introducing passage 20 and the atmospheric pressure introducing passage 21 are connected twice. When negative pressure is introduced into the pressure chamber 18b by opening and closing reciprocally by the first and second electromagnetic valves 22 and 23 of the formula, the relief valve 19 is lifted to communicate the bypass air passage 17, and By opening the pressure chamber 18b to the atmosphere, the pressure chamber 18b
The relief force of the coil spring 18c therein closes the relief valve 19.

Also, when the engine 1 is idle, the throttle valve 12
An idle air passage 24 for supplying the intake air required for idling is provided by connecting the intake air passage 2 and the bypass air passage 17 slightly upstream of the throttle valve 12 held at the idle opening degree. Cage, idle air passage 24
An electromagnetic idle flow rate adjusting valve 25 for adjusting the flow rate of idle air is provided in the middle of.

Further, the operation lever 26 of the throttle valve 12 is connected to the step motor 28 for auto-cruise through the operation rod 27 so that the throttle valve 12 during auto-cruising operation can be operated.
Control the opening of.

The electromagnetic clutch 6, the fuel injection valve 16, the double type first and second electromagnetic valves 22 and 23, the idle flow rate adjusting valve 25, the step motor 28 for auto cruise, and the like are controlled by a control circuit 29 including an in-vehicle computer. Drive control.

The control circuit 29 is an intake air amount detected by the air flow meter 11, and an opening sensor provided for the throttle valve 12.
Throttle opening detected by 30, surge tank 13
In addition to the supercharging pressure detected by the pressure sensor 31, engine speed, engine cooling water temperature, shift position (gear position), ON / OFF of the auto cruise switch, etc. are used as input information, for example, fuel injection at every moment. The amount is calculated to control the fuel injection valve 16.

The control by the control circuit 29 is diverse as described above, but the fuel control, the idle flow rate control, and the like are conventionally known controls, and a description thereof will be omitted. Below, the supercharging pressure which is the subject of the present invention will be described. The control will be described.

The supercharging pressure control is performed as drive control of the first and second electromagnetic valves 22 and 23 provided for the negative pressure introducing passage 20 and the atmospheric pressure introducing passage 21 of the electromagnetic clutch 6, the actuator 18, and the relief valve 19 respectively.
By controlling the opening and closing of, the boost amount is adjusted and the boost pressure is adjusted.

The supercharging pressure control characteristics in that case are shown in FIG. 2 when the throttle valve 12 is fully opened, and in FIG. 3 when the engine speed (speed) is constant.

As shown in FIG. 2 and FIG. 3, the supercharging pressure control according to the present invention is performed by changing the shift position (gear position) of the mounted transmission.
The boost pressure is the lowest at the 1st speed, and the set boost pressure is sequentially increased as the speed increases from the 2nd speed to the 3rd speed to the 4.5th speed.

When the auto-cruise switch is turned on, as shown by the dotted line in FIG. 3, control is performed so that the boost pressure is about the middle of the boost pressures of the first speed and the second speed. In FIG. 2, the set boost pressure at the time of auto-cruise is shown by a dotted line for reference although it is not in the fully open operation.

That is, as shown in FIGS. 2 and 3, the control circuit 29 calculates the supercharging pressure to be set from the engine speed at that time and the throttle opening TVO according to the gear stage of the transmission. When the supercharging pressure detected by the pressure sensor 31 exceeds the calculated value and is about to rise, the relief valve 19 is opened to control the supercharging pressure to the calculated value.

As described above, when the low speed gear such as the 1st speed or the 2nd speed, in which the degree of change of the engine speed with respect to the change of the vehicle speed is large, is selected, the rotation fluctuation of the vane pump 7 itself becomes large, but the boost pressure is Since the setting is controlled to a low value, excessive pressure does not act on the vanes during rotation fluctuations, deflection of the rotating shaft is also reduced, and it is possible to affect the durability of the oil seal and belt. Become.

When the auto-cruise switch is turned on to shift to auto-cruising, the opening degree of the throttle valve 12 is automatically set by the auto-cruise step motor 28. For example, as shown by an arrow A in FIG. If the vehicle shifts to auto cruising while in 5th speed, the throttle opening TVO ₁ to TVO _{2 is} set to a large value, and the target boost pressure is also set to be lower than that in 2nd speed. The pressure drops.

Therefore, the load on the supercharger is reduced, and the pumping loss is reduced by increasing the throttle opening, which improves fuel efficiency.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an engine according to an embodiment of the present invention, FIGS. 2 and 3 show supercharging pressure control characteristics, FIG. 2 is at full open operation, and FIG. 3 is at constant rotation speed. The characteristics are shown respectively. 1 …… Engine, 2 …… Intake passage, 7 …… Vane pump, 17 …… Bypass air passage, 18 …… Actuator, 19 …… Relief valve, 22,23 …… First and second solenoid valves, 29 …… Control circuit.

Claims (1)

[Claims] Claim: What is claimed is: 1. In an engine having a mechanical supercharger driven by an engine output shaft in an intake passage, a shift position detecting means for detecting a shift position of the transmission and an output of the shift position detecting means to shift a gear. An intake system for an engine with a mechanical supercharger, comprising: a supercharging pressure control means for controlling the supercharging pressure to be lower as the position is lower.