FIELD OF THE INVENTION:

The invention relates to a device and method for supplying air to an IC engine. Typically the invention relates to supplying air to gasoline engines of smaller capacity.

BACKGROUND OF THE INVENTION:

In a vehicle having a mechanically controlled throttle, the sizing of the throttle body depends on the target power and torque characteristics of the vehicle. For a small throttle opening the velocity of flow of air will be greater than a bigger throttle opening. When the throttle opening is bigger the required velocity can be achieved by the engine speed. Thus a smaller throttle opening achieves the required air flow when the engine speed is less but when engine speeds is higher, the required flow velocity can be achieved simply by the engine speed where the requirement is to supply as much air as possible by a bigger opening hence bigger throttle opening is required at higher engine speeds.

Selection of a throttle with a smaller bore diameter helps to improve the power and toque characteristics at lower engine speeds but reduces peak power at higher engine speeds. Selection of a throttle with a bigger bore diameter helps to improve the power and toque characteristics at higher engine speeds but increases the overall cross-sectional area of the throttle valve which increases the leakage of air through the throttle body when the throttle valve is completely closed. The problem is greater if the air leakage increases as the engine requirement at idling may not be met and the stability of the vehicle in the idling operating condition will be poor. Also a throttle with a bigger bore diameter occupies more space and increases cost of product and maintenance costs.

In a vehicle with an engine management system and having mechanical throttle actuation (throttle body), an Idle speed actuator is provided to keep the vehicle at set idle speed, to aid the starting of the vehicle at different temperature and pressure at different altitudes and to keep vehicle in running condition during coast down (down hill driving with throttle flap completely closed). The idle speed actuator is typically controlled by an electronic controller.

DESCRIPTION OF THE INVENTION:

The present invention discloses a device for supplying air to an engine. A throttle valve is positioned in an air path connecting the air inlet to the engine. A bypass path connects one side of the throttle valve to the other side of the throttle valve. The bypass path is provided with a valve to vary the opening of the bypass path. A controller is adapted to control the opening of the bypass valve when the throttle valve is open based on power or torque requirements of the engine. Thus, opening of the bypass valve when the throttle valve is open will help to achieve power or torque requirements of the engine.

The throttle size can be reduced as a result of using a device in accordance with this invention. This in turn reduces the material required for the throttle passage and the throttle valve. The cost of the device also reduces. Improved performance can be achieved for smaller throttle sizes.

BRIEF DESCRIPTION OF THE DRAWINGS:

The invention is now described in reference to the accompanying drawings

Fig. 1 shows a schematic diagram of the device for supplying air to an engine in accordance with this invention;

Fig. 2 illustrates two air supplying devices with throttle opening d and D, wherein D>d;

Fig. 3 shows a graphical representation and comparison of performance of the engine with and without the device in accordance with the present invention; and

Fig. 4 of the accompanying drawings illustrates a flowchart for operation of the device in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS:

Fig. 1 illustrates a schematic diagram of a device for supplying air to an engine in accordance with this invention. The device comprises a throttle valve (12) which is positioned in an air inlet path (10) which provides air to the engine. There is a bypass path (14) connecting one side of the throttle valve (12) to the other side of the throttle valve (12). In the bypass path (14) is located a bypass valve (16) to control the amount of air flow through the bypass path (14). The bypass valve (16) is open during idling of the engine based on the idling requirements. The throttle valve (12) is opened only when the driver demands for more power by pressing the accelerator pedal. The device includes a controller (18) to determine the additional air requirement of the engine when the throttle valve (12) is near to complete open position and adjusts the bypass valve (16) opening accordingly.

Typically the throttle valve (12) is mechanically operated. The user directly controls the opening of the throttle valve (12). As the user requirement for the power increases the user input drives the throttle valve (12) from a closed position to a fully open position. The bypass valve (16) is electronically controlled by the controller (18). To achieve peak power or torque the engine requires sufficient quantity of air. To provide the required quantity of air to the engine, the controller (18) determines the additional air requirement based on the power and torque requirement. This additional air is supplied by opening of the bypass valve (16). As the power requirement increases when the throttle valve (12) is near to complete open position or when in complete open position then the controller opens the bypass valve (16) to achieve the peak power or torque.

Fig. 2 illustrates two embodiments for an air supplying device with throttle valve (12) opening d and D, wherein D>d. The performance of an engine in terms of power output with a larger throttle opening is good at higher engine speeds but not satisfactory at low engine speeds. Whereas the power output of the engine with a smaller throttle opening is satisfactory for low engine speeds and substantially deteriorates beyond a peak threshold engine speed. The performance graphs for the same are illustrates in fig. 3.

Fig. 3 illustrates a graph of engine power against engine speed for comparing the performance of the engine with and without the air supply device in accordance with this invention. The graph A shows the performance of the engine when the maximum throttle opening is "d" and graph B shows the performance of the engine when the maximum throttle opening is "D". With reference to the two embodiment shown in figure 2, the diameter D of the throttle opening in the first embodiment is greater than the diameter d of the throttle opening in the second embodiment (D>d). It is observed that at higher engine speeds with a smaller throttle opening "d", the power begins to reduce beyond a particular engine speed. For throttle opening "D", the performance of the engine is poor as compared to smaller throttle "d" at lower engine speeds but it is significantly better at higher speeds. Neither the small throttle opening "d" nor comparatively larger throttle opening "D" give good performance throughout the range of the engine speed operation.

The device in accordance with the invention has a smaller throttle valve (12) opening and is provided with the adjustable bypass path (14) for achieving peak power. When the device for supplying air in accordance with this invention is used, the performance graph of the engine is illustrated by graph C. It can be observed that at low engine speeds for a smaller throttle opening, the performance achieved is as desired. When the engine is operating at higher speeds then beyond a particular speed the controller (18) will actuate the bypass valve (16) to open and thus the air entering the engine would increase. Thus, the effective throttle valve (12) opening will be larger. Thus, the performance achieved at higher engine speeds is similar to having a larger throttle opening. It can be observed that the performance of engine with a device in accordance with this invention is optimum throughout the engine speed variations.

Fig. 4 illustrates the method of operation of the device in accordance with this invention. The device in accordance with this invention detects the throttle open condition (SO). The device has a predetermined threshold for the throttle opening stored in it. The threshold position corresponds to near complete opening of said throttle valve. The device compares the throttle opening with a threshold position (S1). When the throttle opening is equal to or greater than the threshold, the device detects the opening of the throttle as need for additional air intake to achieve the peak power and torque. The controller opens of the bypass valve when the throttle position is opened beyond the threshold to aid intake of additional air (S2). This has the same effect as having a throttle opening of a larger size. Thus, the peak power or torque requirements of the engine can be reached.

It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

WE CLAIM:

1. A device for supplying air to an engine, said device comprising an air path (10) connecting an air inlet to the engine;

a throttle valve (12) positioned in said air path (10);

a bypass path (14) connecting one side of the throttle valve (12) to the other side of the throttle valve (12),

said bypass path (14) provided with a bypass valve (16) to vary the opening of the bypass path (14); said device characterized by

a controller (18) adapted to control the opening of the bypass valve (16) when said throttle valve (12) is open based on power or torque requirements of the engine.

2. A device as claimed in claim (1) wherein the throttle valve (12) is mechanically actuated based on the user input.

3. A device as claimed in claim (1) wherein the bypass valve (14) is electronically actuated.

4. A device as claimed in claim (1) wherein, said controller (18) determines additional air requirement to achieve peak power output at high throttle valve (12) open positions.

5. A method for supplying air to an engine, detecting of throttle open condition (SO);

comparing the throttle opening with a threshold position (S1); controlling the opening of the bypass valve when the throttle position is opened beyond the threshold based on power or torque requirements of the engine (S2).

6. A method as claimed in claim (5) wherein during the idling state the bypass valve is opened according to the idling requirements and the throttle valve is closed.

7. A method as claimed in claim (5) wherein said threshold position corresponds to near complete opening of said throttle valve.

8. A method as claimed in claim (5) wherein during high throttle operating conditions, the bypass valve is opened to achieve peak power output.

9. A method as claimed in claim (5) and (8) wherein opening of the bypass valve is electronically controlled based on the peak torque and power requirements to compensate for the additional air requirement when throttle is near to complete open position.