JPH053714Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a boost pressure control device for an internal combustion engine equipped with a mechanical supercharger.

[Conventional technology]

In internal combustion engines equipped with mechanical superchargers such as roots pumps or vane pumps, the exact pump efficiency of the supercharger differs from one engine to the next, so it is difficult to use superchargers manufactured on the same production line in the engine. Even if installed, engine performance may differ from engine to engine. Variations in pump efficiency appear as variations in initial performance due to manufacturing and assembly errors, or as variations over time after assembly into the engine, but in any case, variations in engine performance are due to A pump that is large in the rotational range and has low efficiency will have an extremely low low-speed output, and will overcharge in the high-speed rotational range, causing problems with pressure resistance of parts and greatly reducing fuel efficiency.

It is known that a mechanical supercharger is also provided with a relief valve equivalent to the waste gate valve of a turbocharger in order to control the upper limit of supercharging pressure. Therefore, the opening set pressure of the relief valve is normally set to a value as close as possible to the maximum pressure limit determined in design from the viewpoint of the pressure resistance of the engine.

[Problem that the invention attempts to solve]

The problem to be solved by this invention is, in view of the above-mentioned conventional technology, how to reduce the variation in engine supercharging characteristics in the low rotation range and ensure low-speed output, given the variation in pump efficiency. Another issue is how to prevent the supercharger from heating up during idling and improve fuel efficiency.

Therefore, the present invention uses a pump with higher performance than required to ensure low-speed output, and also relieves the discharge pressure of the supercharging pump using negative pressure downstream of the throttle valve and upstream of the supercharging pump during idling, thereby solving the above problems. This is an attempt to solve the problem. In other words, by using a high-performance pump or by increasing the speed increase ratio of the pump, the entire pump characteristic curve is shifted in parallel to the high-performance side, and as a result, the pump discharge pressure is already increased in the low-speed region of the engine. Ensure that the boost pressure is close to the relief valve opening setting. As a result, in a pump with a high boost pressure, the boost pressure is relieved in the low rotation range and becomes stable. Also, during idling, the large negative pressure that acts downstream of the throttle valve and upstream of the supercharging pump relieves the pump's discharge pressure. As a result, the negative pressure downstream of the throttle valve and upstream of the supercharging pump is prevented from becoming too large, preventing the supercharging pump from overheating, and reducing the driving torque of the supercharging pump to improve fuel efficiency. do.

[Means for solving problems]

According to the present invention, in order to solve the above problems,
Use a high-performance supercharging pump whose discharge pressure is close to the opening pressure value of the pressure regulating valve in its low rotation range, or increase the speed of the pump to obtain such pump drive characteristics. In addition, the pressure regulating valve opens when the discharge pressure downstream of the supercharging pump exceeds a predetermined value, and when the negative pressure upstream of the supercharging pump downstream of the throttle valve opens during idle or deceleration. The valve is characterized by opening when a large negative pressure is reached, which is the case when the load is low.

As is clear from the above configuration, in the present invention, the opening set pressure of the pressure regulating valve is determined by the sum of the discharge pressure downstream of the supercharging pump and the negative pressure downstream of the throttle valve and upstream of the supercharging pump. will be determined.

〔Example〕

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

FIG. 1 shows the basic configuration of a supercharging control device according to the present invention. In the figure, 1 is an air cleaner, 3 is an air flow meter, 5 is an engine body (E/G), and 7 is an air cleaner.
indicate the throttle valves. A supercharging pump, such as the Roots pump 11, is provided in the intake passage 9 between the engine body 5 and the throttle valve 7, and rotates in accordance with the rotation of the engine 5 to supercharge the engine.

The above configuration is completely the same as the conventional one.

A pressure regulating valve 15 is provided downstream of the pump 11. The pressure regulating valve 15 opens when the boost pressure (discharge pressure) exceeds a predetermined value and releases the discharge pressure to the relief passage 19.
It opens to the intake passage 9 upstream of the pump. The relief passage 19 bypasses the pump 11 and connects the upstream side and the downstream side of the pump 11. In general, the opening set pressure of the pressure regulating valve 15 is slightly lower than the maximum limit pressure determined from the viewpoint of the engine's pressure resistance, etc., with a safety factor taken into consideration, in order to ensure as much supercharging as possible. A value is selected.

However, even if the pumps 11 are manufactured on the same production line, it is unavoidable that the efficiency of the pumps 11 varies from pump to pump as shown in A, B, and C of FIG. Such variations in pump efficiency may originally occur during the manufacturing or assembly stage, or may occur as a result of changes over time after assembly and use. In any case, for example, the variation between three pumps P, B, and C is
As shown in the figure, the smaller the engine speed, the larger the area.

Therefore, in the present invention, as shown in FIG. 3D, the problem is solved by using a supercharging pump having a higher pump efficiency than required or by increasing the speed increasing ratio of the pump. In other words, the pump efficiency curve is shifted approximately parallel to the high performance direction of the pump efficiency, and therefore, the pump discharge pressure is lower than the pressure regulating valve 15 in the region where the engine speed is considerably low.
When the valve-opening set pressure of 1 is reached, the pressure regulating valve 15 relieves the pressure over almost the entire operating range, so that variations in pump efficiency in the low rotation range are almost completely absorbed. Moreover, since the present invention uses such a high supercharging pump, the necessary supercharging pressure (pump discharge pressure) is ensured.

In order to increase the supercharging capacity of a pump, it is generally sufficient to use a pump with a large pump capacity or to increase the speed increasing ratio of the pump.

Fig. 3 shows the relationship between the pump characteristics and pressure regulating characteristics when using the supercharging pump according to the present invention.As is clear from the figure, according to the present invention, the pressure regulating characteristics are The pump discharge pressure exhibits a pressure characteristic higher than the regulating characteristic.

Further, the supercharging pressure is also relieved during idle rotation.

FIG. 2 shows an example of the structure of the pressure regulating valve 15. The pressure regulating valve 15 is composed of a valve housing 23 having a pressure relief port 21 that opens into the intake passage on the downstream side of the pump 11. Inside the valve housing 23 is a valve body 2 which is always biased to the valve closing position by a spring 39.
7 is provided, and the port 21 is opened and closed by a valve body 27. When the port 21 is opened, the relief passage 1
Connects with 9.

As a result, by appropriately designing the initial load of the spring 25, the pressure regulating valve 15 can be
The valve opening pressure can be set arbitrarily. In addition, the pressure is more likely to be relieved in the high-speed, high-load range, and the characteristics shown in FIG. 4 are obtained, which improves torque at low speeds, reduces intake and exhaust temperatures at high speeds, and improves fuel efficiency.

The valve body 27 is connected to a diaphragm 33 by an actuation rod 31. The diaphragm 33 is a diaphragm housing 3 fixed to the valve housing 23.
7, and is always biased by a spring 39 toward the valve closing position of the valve body 27. The diaphragm operating chamber (pressure control chamber) 41 is connected via the pressure sensing tube 17 to the intake passage 9 downstream of the throttle valve 7 and upstream of the pump. Therefore, the diaphragm 33
operates in response to the intake negative pressure downstream of the throttle valve 7 to open and close the port 21. In this way, the valve body 27 is pulled down by the large negative pressure acting on the diaphragm 33 even when the valve body 27 is idling or when the negative pressure is larger than the idle time or when the load is low such as during deceleration, so that the discharge pressure is relieved. I can do it. This prevents the negative pressure downstream of the throttle valve and upstream of the supercharging pump from becoming excessive, which in turn prevents the supercharging pump from heating up, and reduces the supercharging pump driving torque to improve fuel efficiency. I can do it.
Furthermore, at high load and high rotation when the throttle valve 7 is fully opened, a pressure that is substantially lower than atmospheric pressure acts on the diaphragm chamber 41, and the pressure becomes lower as the rotation and load increases (higher intake air amount). The valve body 27 is opened and closed by the discharge pressure of the pump 11 and the negative pressure applied to the diaphragm chamber.

[Effect of idea]

As described above, according to the present invention, the pressure regulating valve opens when the discharge pressure downstream of the supercharging pump exceeds a predetermined value.
It is possible to prevent the supercharging pressure entering the engine from becoming excessive, and to prevent overcharging by opening the valve when the negative pressure downstream of the throttle valve and upstream of the supercharging pump reaches a large negative pressure, for example, during idling. By returning the pressure downstream of the feed pump to the upstream side of the supercharging pump, it is possible to prevent excessive negative pressure between the throttle valve and the supercharging pump, which in turn can prevent the supercharging pump from generating heat. Fuel efficiency can be improved by reducing the driving torque of the supercharging pump. In addition, by using a high boost pump that closes to or exceeds the set opening pressure of the pressure regulating valve in the low engine speed range, the required boost pressure is secured even in the low engine speed range. By simultaneously relieving the supercharging pressure, variations in pump efficiency can be absorbed.

[Brief explanation of the drawing]

Fig. 1 is an illustrative diagram showing the overall configuration of the supercharging control device according to the present invention, Fig. 2 is a diagram showing an embodiment of the pressure regulating valve shown in Fig. 1, and Fig. 3 is a diagram showing the pump efficiency according to the present invention. FIG. 4 is a diagram showing the relationship between pump characteristics and pressure regulating characteristics according to the present invention; FIG. 5...Engine body, 11...Supercharging pump, 1
5...Pressure regulating valve, 19...
relief passage.

Claims (1)

[Scope of utility model registration request] A mechanical supercharging pump 11 is installed in the intake passage 9 of the internal combustion engine.
A throttle valve 7 is disposed upstream of the supercharging pump, and a relief passage 19 is provided extending from an intake passage between the throttle valve and the supercharging pump to downstream of the supercharging pump. A pressure regulating valve 15 is provided in the passage, which opens when the discharge pressure downstream of the supercharging pump increases and also opens when the negative pressure downstream of the throttle valve and upstream of the supercharging pump exceeds the negative pressure that acts at idle.
1. A supercharging control device for an internal combustion engine, characterized in that the discharge pressure of the supercharging pump used reaches near a predetermined opening set pressure value of a pressure regulating valve in a low engine rotation region.