JPH05179975A - Internal combustion engine having variable supercharge device - Google Patents

Abstract

PURPOSE:To obtain a mechanically driven supercharger having a transmission mechanism which can keep supercharging performance at the time of supercharge operation and can improve torque recovery efficiency under non-supercharging operation at the same time. CONSTITUTION:In an internal combustion engine 48, a mechanically driven supercharger 10 which is driven by the engine 48 is arranged on an intake pipe 4, and a varying transmission 20 is provided for transmitting driving force to the supercharger 10. A recovery torque is proportional to a differencial pressure in the mechanically driven supercharger 10 and a speed ratio of the varying transmission 20 when the mechanically driven supercharger 10 is driven through a negative pressure on the side of the internal combustion chamber 48. The smaller the speed ratio is, the larger the differencial pressure is, so that the recovery torque shows a maximum value when the speed ratio is equal to be a certain value. An internal combustion engine 1 having a varying supercharge device has a control means 30 which keeps the speed ratio corresponding to the maximum value of the recovery torque when the internal combustion engine 48 is operated in a low load, so that the torque recovery is carried out with high efficiency. Under a high load operation, on the other hand, the speed ratio is increased in proportion to the load of the internal combustion engine 48. Rotational number of the mechanically driven supercharger is thus increased, bringing about a supercharging condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine with a mechanical supercharger for supplying supercharged air to the internal combustion engine by driving the supercharger with the rotational driving force of an output shaft (crankshaft or the like) of the internal combustion engine. Regarding the institution. In particular, the present invention relates to an internal combustion engine with a variable supercharging device in which a variable transmission capable of changing a gear ratio is provided between a supercharger and an output shaft to make an air supply amount variable.

[0002]

2. Description of the Related Art A technique called a mechanical supercharger has been put into practical use in order to increase the output of an internal combustion engine such as an engine. In this technique, the supercharger is driven by utilizing a part of the driving force generated on the output shaft of the internal combustion engine. According to this, the intake amount increases more than the amount of reduction in the output that occurs due to driving the supercharger, and as a result, the engine output increases. In this system, the supercharger becomes a resistance to the intake air flow while the engine is rotating at a low speed. Therefore, in JP-A-60-209627, a variable transmission is provided between the supercharger and the output shaft,
The lower the engine speed, the smaller the gear ratio, and the ratio of the engine speed to the turbocharger speed. With this configuration, while the engine is rotating at a low speed, the supercharger is rotated by the intake air flow, which is transmitted to the output shaft to rotate the output shaft of the engine. That is, the technique disclosed in the above publication intends to use the supercharger as an air motor when the engine rotates at a low speed.

[0003]

In the above internal combustion engine with a variable supercharging device, the gear ratio is controlled to be proportional to the load of the internal combustion engine over the entire region of non-supercharging operation. However, as a result of intensive studies by the present inventors, when the gear ratio is decreased in proportion to the decrease in the engine speed, the output recovered by the supercharger (that is, the work per unit time corresponds to the work rate). It was found that the efficiency as an air motor becomes very low.
Therefore, it is an object of the present invention to provide an internal combustion engine with a variable supercharging device capable of improving the torque recovery efficiency during non-supercharging operation while maintaining the supercharging performance during supercharging operation.

[0004]

In order to solve the above problems, the present invention provides a mechanical supercharger provided in the middle of an intake pipe of an internal combustion engine with a driving force generated on an output shaft via a variable transmission. In an internal combustion engine with a variable supercharger driven by
During low load operation of the internal combustion engine, the power ratio obtained by rotating the mechanical supercharger by the intake air flowing through the intake pipe is substantially maximum with respect to the speed ratio of the variable transmission with respect to the speed ratio. Internal combustion engine with a variable supercharging device, which is provided with a control means for holding the gear ratio to a predetermined value and increasing the gear ratio in proportion to the load of the internal combustion engine during high load operation of the internal combustion engine. Created an institution.

[0005]

In the internal combustion engine with a variable supercharger according to the present invention having the above-described structure, when the mechanical supercharger is driven by the negative pressure generated on the internal combustion engine side to recover the torque, it is recovered. The magnitude of the torque that depends on the pressure difference in the mechanical supercharger and the gear ratio of the variable transmission. Here, the pressure difference of the mechanical supercharger is also an amount that depends on the gear ratio of the variable transmission, and the smaller the gear ratio of the variable transmission, the larger the pressure difference. Eventually, the magnitude of the recovered torque becomes a multi-dimensional function related to the gear ratio of the variable transmission, and has a maximum value with respect to the gear ratio. The internal combustion engine with the variable supercharging device of the present invention has the control means for holding the gear ratio of the variable transmission at a predetermined value that maximizes the recovery torque when the internal combustion engine is operating at low load. Therefore, during low load operation, the torque is highly efficiently recovered. On the other hand, during high-load operation of the internal combustion engine, the gear ratio is increased in proportion to the load of the internal combustion engine, so that the rotational speed of the mechanical supercharger increases and the supercharged state occurs. In this way, it is possible to improve the torque recovery efficiency during non-supercharging operation while maintaining the supercharging performance during supercharging operation.

[0006]

【Example】

First Embodiment Next, a first embodiment embodying the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is an overall configuration diagram showing a first embodiment of an internal combustion engine with a variable supercharger according to the present invention. In FIG. 1, reference numeral 1 is an internal combustion engine with a variable supercharger, and the internal combustion engine 1 with a variable supercharger includes a supercharger 10 for forcibly sending air to a vehicle engine 48 as an internal combustion engine, This supercharger 10 has an engine 48
Toroidal variable transmission (hereinafter referred to as CVT) that transmits the rotational driving force of the crankshaft 42 of the CVT while changing the rotational speed.
20) and a CVT gear ratio controller 30 that changes the gear ratio of the CVT 20.

The amount of air supplied from the air cleaner 2 through the intake pipe 4 is controlled by a throttle valve 6 provided in the intake pipe 4 and a supercharger 10. And
The controlled air amount is supplied to the engine 48 through the intake pipe (intake manifold) 44. The supercharger 10 includes a crankshaft 42 of an engine 48, a pulley 40, a belt 38, a pulley 36, and a CVT 20.
Driven by the driving force transmitted through the CVT2
The gear ratio of 0 controls the rotation ratio of the supercharger 10 to the engine speed.

This CVT (toroidal type continuously variable transmission) 2
As shown in FIG. 1, 0 is an input disk 32 that rotates integrally with the input shaft 34, an output disk 24 that rotates integrally with the output shaft 22, and two disks 3.
A plurality of power rollers 26, which are sandwiched between 2 and 24, are mainly configured. The pulley 36 is fixed to the input shaft 34, and the rotary shaft of the supercharger 10 is fixed to the output shaft 22. Then, the rotation of the input disk 32 is transmitted to the output disk 24 via the power roller 26 rotating around the power roller shaft 28. At the same time, by changing the inclination of the power roller shaft 28, the position where the power roller 26 contacts the input / output disks 32, 24 changes. As a result, the gear ratio of the CVT 20 is changed.

Information on the amount of depression of the accelerator pedal 60 detected by the accelerator sensor 54 and the engine 48 detected by the engine speed sensor 52.
The optimum pulley transmission mechanism 36,
The gear ratios of 38, 40, and CVT 20 are calculated by the control computer 50. Calculated CVT
The inclination of the power roller shaft 28 is changed by the CVT gear ratio controller 30 according to the gear ratio. As a result, the gear ratio by the CVT 20 is changed, and the gear ratio is controlled by the pulley transmission mechanisms 36, 38, 40 and the CVT 20. That is, the CVT gear ratio controller 30 embodies the control means of the present invention, and the gear ratios of the variable transmissions 20, 36, 38, 40 are set to the intake pipe 4, when the internal combustion engine 48 is operating at low load.
The work rate obtained by rotating the mechanical supercharger 10 by the intake air flowing through 44 is maintained at a predetermined value at which the power ratio becomes substantially maximum with respect to the gear ratio. Further, during high load operation of the internal combustion engine 48, the gear ratio increases in proportion to the load of the internal combustion engine 48. The opening of the throttle valve 6 changes according to the depression amount of the accelerator pedal 60.

In the internal combustion engine 1 with a variable supercharging device having the above-described structure, when the torque is recovered by driving the supercharger 10 with the negative pressure generated on the engine 48 side, the magnitude of the torque recovered. Consider ΔT (engine crankshaft conversion). The gear ratio of the number of rotations by the pulley transmission mechanisms 36, 38, 40 and the CVT 20 is R, the transmission efficiency of the CVT 20 is η, and the discharge amount per rotation of the supercharger 10 is Q.
p, and the pressure difference in the supercharger 10 is ΔP,
T is represented by the following equation (1). ΔT = Rη (Qp / 2π) ΔP (1) Here, the pressure difference ΔP of the supercharger is Qe, which is the displacement of the engine 48 per revolution, and Ne, which is the revolution speed of the engine 48.
When the rotation speed of the supercharger 10 is Np, it is expressed by the following equation (2). ΔP = (Qe Ne-Qp Np) / K (2) where K is a constant. Since R = Np / Ne, the following equation (3) is obtained by rearranging equations (1) and (2). ΔT = (ηQp Ne / 2πK) · (Qe R−Qp R ² ) (3)

As can be seen from the equation (3), ΔT is a quadratic curve which is convex upward with respect to R. Therefore, there is a value of the gear ratio R that maximizes the value of the recovery torque ΔT. Differentiating both sides of the equation (3) by R gives the following equation (4). d.DELTA.T / dR = (. eta.Qp Ne / 2.pi.K) .multidot. (Qe-2Qp R) (4) In equation (4), if d.DELTA.T / dR = 0, then Qe =
2Qp R, and therefore the following equation (5) is obtained. R = (Qe / 2Qp) (5) Therefore, the value of the gear ratio R that maximizes the value of the recovery torque ΔT is R = (Qe / 2Qp). In the internal combustion engine 1 with the variable supercharging device of the present embodiment, in the low load operation region of the internal combustion engine 48, the CVT gear ratio controller 30 is set so that the gear ratio R is maintained at a predetermined value at which this maximum recovery torque is obtained. The CVT 20 is controlled by.

Now, the control of the CVT gear ratio in the internal combustion engine 1 with a variable supercharger having the above structure will be described with reference to FIG. FIG. 2 is a characteristic diagram showing the above-described control of the gear ratio R by the internal combustion engine 1 with the variable supercharging device according to the present embodiment. In FIG. 2, the horizontal axis represents the accelerator pedal 60.
And the vertical axis is the gear ratio R, the opening degree θth of the throttle valve 6, and the boost pressure P _B of the internal combustion engine 48 in order from the top. Here, the gear ratio R is R = R _P × R _CVT , where R _P is the gear ratio of the pulley transmission mechanism including the pulley 40, belt 38, and pulley 36 shown in FIG. 1, and R _CVT is the gear ratio of only the _{CVT 20.} Given in. In this embodiment, the gear ratio R _P is constant.

In the low accelerator pedal depression region Z1, the gear ratio R has a substantially constant characteristic of R = R1. Here, in the present embodiment, the displacement Qe of the engine 48 per revolution is 0.8 liters (corresponding to the case where the 4-cycle engine displacement is 1.6 liters), and the discharge amount of the supercharger 10 per revolution. Qp is 1.0 liter. Therefore, the value of R1 that gives the maximum recovery torque is R1 = 0.8 / (2 × 1) = 0.4 from the equation (5).
Becomes Further, in the middle accelerator pedal depression area Z2 and the high accelerator pedal depression area Z3, the gear ratio R is gradually increased to the maximum value R2 when the accelerator pedal depression amount X = 100%. Note that R1 <R2.

The throttle opening θth may be increased to almost 100% in the low accelerator depression area Z1 and maintained at 100% in the medium / high accelerator depression areas Z2 and Z3, or may be a characteristic such as Y2. It may be a characteristic such as Y1 that increases linearly according to the accelerator depression amount X. Which characteristic should be selected should be selected according to the engine torque characteristic required for the accelerator depression amount, but a characteristic such as Y1 is desirable in order to reduce the pumping loss of the engine 48 as much as possible.

By providing the characteristics of the gear ratio R and the throttle valve opening θth as described above, the torque recovery region (low / medium accelerator pedal depression regions Z1, Z2) to the supercharging region (high accelerator pedal depression region Z3) are extended. Smooth engine torque characteristics can be obtained. At the same time, the gear ratio R can be set to a value close to R1 = 0.4 in most of the torque recovery region, and the efficiency of torque recovery can be maximized and therefore the fuel consumption can be maximized.

Second Embodiment Next, a second embodiment embodying the present invention will be described with reference to FIGS. 1 and 3. The internal combustion engine with the variable supercharger of the present embodiment is the internal combustion engine 1 with the variable supercharger of the first embodiment.
It has a structure similar to that shown in FIG.
FIG. 3 is a characteristic diagram showing the control of the gear ratio R in the internal combustion engine with the variable supercharging device according to the present embodiment. In FIG. 3, the horizontal axis is the accelerator pedal depression amount X, and the vertical axis is the gear ratio R. Furthermore, the engine speed Ne is taken as a parameter.

As shown in FIG. 3, also in this embodiment, the gear ratio R = in the low accelerator pedal depression region Z1.
The characteristics are almost constant with R1, and the value of R1 is 0.4 when the displacement of the engine 48 per revolution is 0.8 liters and the discharge amount of the supercharger 10 per revolution is 1.0 liter. There is. In the middle accelerator pedal depression area Z2 and the high accelerator pedal depression area Z3, the speed ratio R is gradually increased to the maximum value R2 at X = 100%. However, in this embodiment,
The maximum value R2 of the gear ratio R is changed according to the engine speed Ne. That is, as shown in FIG. 3, the engine speed Ne is from 4000 rpm to 3000,200.
R2 is gradually increased as it decreases to 0,1000. This makes it possible to compensate for the insufficient torque of the engine in the low rotation range, and to realize better engine characteristics.

In each of the above-described embodiments, the _CVT 20 gear ratio R _CVT is controlled by the CVT gear ratio controller 30, but this is performed by limiting the gear ratio R _CVT due to the mechanical structure of the _{CVT 20.} You can also That is, the input disk 3 that constitutes the CVT 20
2, the power roller 26, the output disk 24 and the like may be combined to set a limit at which the gear ratio does not decrease any more, and the limit may be adjusted to a predetermined value at which the maximum recovery torque is obtained. It should be noted that the value of the predetermined value R1 of the gear ratio R in each of the above-described embodiments is merely an example, and changes depending on various conditions. Further, although the toroidal type continuously variable transmission is used as the variable transmission, other types of variable transmissions may be used. The shape, size, number, material, arrangement, etc. of other parts of the internal combustion engine with a variable supercharger are not limited to those in this embodiment.

Further, as an effect peculiar to the second embodiment, the maximum value R of the gear ratio R becomes smaller as the engine speed Ne becomes smaller.
By gradually increasing the value 2, it is possible to compensate for the torque shortage of the engine 48 in the low rotation speed region, and it is possible to realize better engine characteristics.

[0020]

According to the present invention, the variable gear having a control means for holding the gear ratio of the variable transmission at a predetermined value optimum for torque recovery in the low load operation region and increasing it in accordance with the required load in the high load region. Since the internal combustion engine with the supercharging device was created, the torque recovery efficiency during non-supercharging operation can be improved. This makes it possible to efficiently collect intake loss in the internal combustion engine and improve fuel efficiency.

[Brief description of drawings]

FIG. 1 is a first embodiment of an internal combustion engine with a variable supercharger according to the present invention.
It is a whole block diagram which shows.

FIG. 2 is a C diagram of an internal combustion engine with a variable supercharger according to the first embodiment.
FIG. 6 is a characteristic diagram showing control of a VT gear ratio.

FIG. 3 is a C diagram of an internal combustion engine with a variable supercharging device according to a second embodiment.
FIG. 6 is a characteristic diagram showing control of a VT gear ratio.

[Explanation of symbols]

 1 Internal Combustion Engine with Variable Supercharging Device 4,44 Intake Pipe 10 Mechanical Supercharger 20, 36, 38, 40 Variable Transmission 30 Control Means 42 Output Shaft 48 Internal Combustion Engine

Claims (1)

[Claims] 1. An internal combustion engine with a variable supercharger for driving a mechanical supercharger provided in the middle of an intake pipe of the internal combustion engine with a driving force generated on an output shaft via a variable transmission, wherein In low load operation, the power ratio obtained by rotating the mechanical supercharger by the intake air flowing through the intake pipe is set so that the power ratio of the variable transmission becomes substantially maximum with respect to the speed ratio. An internal combustion engine with a variable supercharging device, comprising: a control means for holding the value at a predetermined value and increasing the speed change ratio in proportion to the load of the internal combustion engine during high load operation of the internal combustion engine.