JP2770368B2 - Mechanical supercharger for internal combustion engines - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical supercharger for an internal combustion engine, and more particularly to an improvement in a mechanical supercharger having a drive system including a continuously variable transmission mechanism and a clutch mechanism.

2. Description of the Related Art A mechanical supercharger including a roots blower and the like is configured to be driven by a crankshaft of an internal combustion engine via a belt transmission mechanism, but in a configuration in which the supercharger is driven at a constant speed ratio, Problems such as insufficient supercharging in the low engine speed range, and excessively high speed rotation of the supercharger in the high engine speed range, lowering the durability are caused.

Therefore, a mechanical supercharging device provided with a continuously variable transmission mechanism has been proposed in, for example, JP-A-63-167027.

This means that, for example, by changing the groove width of the pulley by hydraulic pressure, the effective diameter of the pulley with which the belt comes into contact is changed, and consequently the gear ratio between the crankshaft and the supercharger drive shaft is changed. Thus, the engine speed and the load (for example, the throttle valve opening) are detected, and the optimum gear ratio is determined based on the detected engine speed and the variable gear ratio control is performed.

Even when such a continuously variable transmission mechanism is provided, it is not preferable in terms of fuel efficiency and the like to continue driving the supercharger in a low load region where supercharging is not required at all. A mechanism is also used, and it is possible to stop the supercharger and switch the drive by disconnecting and connecting the clutch mechanism.

Japanese Unexamined Utility Model Publication No. Sho 62-36239 discloses a supercharging device in which a bypass passage for bypassing a mechanical supercharger is provided and a bypass control valve is interposed in the bypass passage. The bypass control valve opens and closes the bypass passage in a manner corresponding to the OFF / ON state of the turbocharger.

However, in the above-described conventional mechanical supercharging device, when acceleration is detected from a change in the opening degree of the throttle valve or the like, the clutch mechanism is connected and the driving of the supercharger is started. At the same time, since the bypass control valve is fully closed, the torque is temporarily reduced due to the inertial weight of the turbocharger, and breathing and so-called engine stall are likely to occur in the initial stage of acceleration, and the feeling of acceleration is likely to be discontinuous.

Means for Solving the Problems Therefore, the present invention provides a mechanical supercharger, a continuously variable transmission mechanism and a clutch mechanism provided between a crankshaft of an internal combustion engine and a drive shaft of the supercharger, and an engine. Means for detecting the load of the engine, means for detecting the number of revolutions of the engine, control means for controlling the gear ratio of the continuously variable transmission mechanism and the clutch mechanism based on the detected load and the number of revolutions, and A bypass passage that bypasses the turbocharger and communicates the upstream side and the downstream side thereof; and a bypass control valve that is interposed in the bypass passage and opens and closes the bypass passage in response to OFF and ON of the supercharger. In a mechanical supercharging device for an internal combustion engine comprising: a buffer means for maintaining a small gear ratio while the turbocharger is stopped, and a gradual change in the opening degree of the bypass control valve at the start of supercharging. It is characterized by having And

When the internal combustion engine accelerates from the non-supercharging range, the above-mentioned clutch mechanism is connected and supercharging starts. At this time, since the speed ratio of the continuously variable transmission mechanism is kept small, the load required to start driving the supercharger is reduced. At the same time, the bypass control valve in the bypass passage is fully closed, but the change in the opening degree is moderated by the buffer means, and a smooth acceleration feeling can be obtained.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration explanatory view showing the configuration of the entire mechanical supercharging device according to the present invention.

In FIG. 1, reference numeral 1 denotes an internal combustion engine, and 2 denotes a mechanical supercharger including a roots blower and the like supported on the side of the internal combustion engine 1. A drive-side pulley 3 is mounted on the crankshaft 1a of the internal combustion engine 1, and a driven-side pulley 4 is mounted on the supercharger 2 side, and a V-belt 5 is wound around both. Drive side pulley 3 and driven side pulley 4
Are configured so that the groove width changes in accordance with the oil pressure, as described later, and these constitute a continuously variable transmission mechanism. An electromagnetic clutch 6 is interposed between the driven pulley 4 and the drive shaft 2a of the supercharger 2 as a clutch mechanism.

The gear ratio of the continuously variable transmission mechanism is controlled by the hydraulic pressure supplied through the hydraulic passage 8. This hydraulic pressure is applied to the internal combustion engine 1
The oil pump 9 is used as a hydraulic pressure source, and is variably controlled to an appropriate pressure by a pressure control valve 10. More specifically, a drive pulse signal having a constant period is given from the control unit 11 to the pressure control valve 10, and the pressure is controlled by controlling the ON duty ratio. Reference numeral 12 denotes a return passage for returning excess oil from the pressure control valve 10 to an oil pan (not shown), 13 denotes a check valve, and 14 denotes an accumulator.

The control unit 11 is configured by a so-called microcomputer system that executes control according to a predetermined program. Reference numeral 15 denotes a crank angle sensor that detects the engine speed, that is, the rotation speed of the crankshaft 1a. Reference numeral 16 denotes a throttle valve opening sensor that detects the opening of a throttle valve 17 as a load on the internal combustion engine 1. Reference numeral 18 denotes an engine intake air amount. These detection signals are input to the control unit 11.

Further, a bypass passage 23 is provided so as to communicate the intake inlet 21 and the intake outlet 22 of the supercharger 2, and a bypass control valve 24 is interposed in the bypass passage 23. A diaphragm type actuator 25 for driving the bypass control valve 24 has a diaphragm 26 in which a first pressure chamber 27 and a second pressure chamber 28 are defined, and a return spring 29 is disposed on the second pressure chamber side. The second pressure chamber 28 is connected to the bypass control valve 24 via the pressure passage 30.
The first pressure chamber 27 communicates with the downstream side and the upstream side of the throttle valve 17 via the pressure passages 31 and 32. An orifice 33 and a check valve 34 are provided in parallel between the pressure passage 31 and the pressure passage 32.

FIG. 2 is a sectional view showing details of the driving pulley 3. The driving pulley 3 includes a pulley fixing bolt 42 having a lubricating oil passage 41 at the center thereof, and a pulley fixing bolt 42
Fixed pulley member 43 fixed to the crankshaft 1a by
And the crankshaft by the pulley fixing bolt 42
1a, which is substantially constituted by a flange member 44 fixed to the distal end, and a movable pulley member 45 located between the fixed pulley member 43 and the flange member 44 and slidable in the axial direction. A belt groove 46 is formed by the slope 43a of the pulley member 43 and the slope 45a of the movable pulley member 45. The movable pulley member 45 is urged by a return spring 47 in a direction in which the groove width of the belt groove 46 decreases. The movable pulley member 45 and the flange member 44
An oil chamber 48 into which lubricating oil is introduced is formed, and the oil pressure similarly acts in a direction in which the groove width of the belt groove 46 is reduced. In addition, 49 is a guide pin. Reference numeral 50 denotes a water pump driving pulley provided integrally with the fixed pulley member 43.

FIG. 3 shows the driven pulley 4 and the electromagnetic clutch 6.
It is sectional drawing which shows the detail of. The driven pulley 4 includes a fixed pulley member 51 fixed to the pulley shaft 4a together with the boss 51a.
And a movable pulley member 52 fitted slidably in the axial direction on the outer periphery of the boss portion 51a, and a belt groove 53 is formed by the both. The movable pulley member 52 is urged by a return spring 54 in a direction in which the groove width of the belt groove 53 decreases. The driven pulley 4 is integrally provided with auxiliary device driving pulleys 55 and 56 for driving auxiliary devices such as a power steering oil pump and an air conditioner compressor. The electromagnetic clutch 6 includes a clutch rotor 57 fixed to the push shaft 4a via an auxiliary device driving pulley 56, and a supercharger 2
Of the clutch rotor 57
Armature plate 58 that can be attached to and detached from the clutch surface of
The armature plate 58 is roughly constituted by a solenoid 59 that attracts the armature plate 58 to the clutch rotor 57 side.

2 and 3 show the state when the oil pressure in the oil chamber 48 is low in the lower half, and the state when the oil pressure is high in the upper half, respectively. That is, the oil chamber is controlled by the pressure control valve 10.
When the supply hydraulic pressure to the supply belt 48 is controlled to be low, the groove width of the belt groove 46 of the driving pulley 3 naturally increases due to the tension of the V-belt 5. Therefore, the effective diameter on the driving side is reduced. At the same time, in the driven side pulley 4, the groove width of the belt groove 53 is reduced by the urging force of the return spring 54, and the effective diameter becomes large. Therefore, the speed ratio (the driven-side rotation speed / the driving-side rotation speed) becomes small, and the supercharger 2 is decelerated.

When the pressure supplied to the oil chamber 48 is controlled to be high by the pressure control valve 10, the groove width of the belt groove 46 of the driving pulley 3 is reduced, and the effective diameter on the driving side is increased. At the same time, in the driven pulley 4, the groove width of the belt groove 53 is increased by the belt tension, and the effective diameter thereof is reduced. Therefore, the gear ratio increases, and the supercharger 2 is driven at an increased speed.

In the above embodiment, the speed ratio is variably controlled based on the engine speed and the load, that is, the throttle valve opening. Similarly, ON / OFF of the electromagnetic clutch 6, that is, the connection of the clutch,
The disconnection is controlled based on the engine speed and the throttle valve opening. Here, when the electromagnetic clutch 6 is OFF, that is, while the supercharger 2 is stopped, the hydraulic pressure supplied to the oil chamber 48 is controlled to be low. Therefore, the driven pulley 4 idles while the gear ratio is kept at a minimum. At this time, the downstream side of the throttle valve 17 has a negative pressure, and this negative pressure is introduced into the second pressure chamber 28 of the actuator 25, so that the bypass control valve 24 is fully opened. Therefore, the bypass passage
Intake is introduced into the engine through 23.

When the throttle valve 17 is suddenly opened from this state and enters the supercharging range, the electromagnetic clutch 6 is turned on and the operation of the supercharger 2 starts. At this time, since the continuously variable transmission mechanism has the minimum speed ratio in advance, the load required for starting up the turbocharger 2 is relatively small, and therefore, a temporary decrease in engine torque is suppressed. Further, since the pressure downstream of the throttle valve 17 becomes atmospheric pressure, the bias control force of the return spring 29 attempts to close the bypass control valve 24, but the discharge of air from the first pressure chamber 27 is suppressed by the check valve 34 and the orifice 33. Therefore, the bypass control valve 24 gradually closes. Eventually, the bypass control valve 24 is fully closed, and the entire amount of intake air is sent to the engine through the supercharger 2.

That is, at the time of rapid acceleration, after the electromagnetic clutch 6 is connected with the minimum speed ratio, the speed ratio of the continuously variable transmission mechanism is gradually increased, but the bypass control valve 24 is increased in accordance with the increase of the speed ratio. Gradually closes. The bypass control valve
Although the opening change speed of the opening 24 changes depending on the size of the orifice 33, the time until the fully closed position is set to be shorter than the owned time until the continuously variable transmission mechanism reaches the maximum speed ratio. . Therefore, as shown by the solid line (a) in FIGS. 4 and 5, the supercharging pressure rises smoothly, and smooth acceleration without hunting or a sense of level difference can be performed.
The broken line (b) in FIGS. 4 and 5 shows the characteristics when the gear ratio is fixed, and the one-dot chain line (c) shows the case where the continuously variable transmission mechanism is provided and the bypass control valve 24 is completely closed. , Respectively.

Next, in the embodiment shown in FIG. 6, a communication hole 61 is opened and closed by a solenoid valve 62 instead of the orifice 33 described above. The solenoid valve 62 is connected to the control unit 11
, A drive pulse signal having a constant period is given, and the discharge amount from the communication hole 61 can be variably controlled by controlling the ON duty ratio.

In this configuration, when the supercharger 2 is stopped, the solenoid valve 62
The solenoid valve 62 completely closes the communication hole 61. Then, at the time of acceleration, that is, at the start of supercharging, energization is started, the communication hole 61 is appropriately opened, and the closing operation of the bypass control valve 24 is adjusted. Here, in particular, the duty ratio of the drive pulse signal of the electromagnetic valve 62 is variably controlled so that the discharge amount in the initial stage of acceleration is relatively large and the discharge amount in the latter period of acceleration is relatively small. Therefore, the bypass control valve 24
Closes relatively quickly at the beginning of acceleration and then closes gently. Therefore, as shown by the two-dot chain line (d) in FIGS. 4 and 5, acceleration of the boost pressure at the start of acceleration can be accelerated and acceleration can be improved. Acceleration becomes possible.

In addition, when the opening degree of the throttle valve 17 changes gradually at a gentle acceleration, the amount of discharge through the communication hole 61 is suppressed to a small value, and the closing speed of the bypass control valve 24 is reduced. Acceleration feeling according to the above can be obtained, which is more preferable.

In the above embodiment, the example of the continuously variable transmission mechanism controlled by the hydraulic pressure has been described. However, the present invention is not limited to this, and it is possible to use a continuously variable transmission mechanism using air pressure or the like. is there. Further, the groove width of the pulley on the turbocharger side may be mainly changed, and the groove width of the pulley on the internal combustion engine side may be changed accordingly.

As is apparent from the above description, according to the mechanical supercharging device for an internal combustion engine according to the present invention, during acceleration, the clutch mechanism is connected in a state where the gear ratio is small, and the bypass control valve is gradually So that the torque at the initial stage of acceleration due to the load at the start of driving the turbocharger can be prevented,
The supercharging pressure can be raised smoothly, and smooth acceleration without hunting and a sense of level difference can be achieved.

[Brief description of the drawings]

FIG. 1 is a structural explanatory view showing an embodiment of a mechanical supercharging device according to the present invention, FIG. 2 is a sectional view of a driving pulley, FIG. 3 is a sectional view of a driven pulley and an electromagnetic clutch, FIG. FIG. 5 is a characteristic diagram showing a change in the supercharging pressure during acceleration, FIG. 5 is a characteristic diagram showing a change in vehicle acceleration during acceleration, and FIG. 6 is a configuration explanatory diagram showing another embodiment of the present invention. 2 ... mechanical supercharger, 3 ... drive side pulley, 4 ... driven side pulley, 6 ... electromagnetic clutch, 10 ... pressure control valve, 11
…… Control unit, 23 …… Bypass passage, 24…
… Bypass control valve, 25… Diaphragm actuator, 33… Orifice, 34… Check valve.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02B 33/00-39/16

Claims (1)

(57) [Claims] 1. A mechanical supercharger, a continuously variable transmission mechanism and a clutch mechanism provided between a crankshaft of an internal combustion engine and a drive shaft of the supercharger, and means for detecting a load on the engine; Means for detecting the number of revolutions of the engine; control means for controlling the speed ratio of the continuously variable transmission mechanism and the clutch mechanism based on the detected load and number of revolutions; and an upstream side bypassing the supercharger. A machine for an internal combustion engine, comprising: a bypass passage communicating between the supercharger and a downstream side; and a bypass control valve interposed in the bypass passage and opening and closing the bypass passage in response to OFF and ON of the supercharger. In the supercharger, the gear ratio while the turbocharger is stopped is kept small,
A mechanical supercharging device for an internal combustion engine, further comprising a buffer means for gently changing a degree of opening of the bypass control valve at the start of supercharging.