JPS63140821A - Supercharger for engine - Google Patents

Abstract

PURPOSE:To improve the torque of an engine by setting the speed ratio of a blower to the engine such that the volume flow of blower becomes smaller than that of engine in high speed and load region. CONSTITUTION:In a turbo supercharger 13, a speed ratio PR is set in the high speed and load region giving the supercharging capacity exceeding required supercharging pressure of an engine such that the volume flow in a mechanical supercharger 16 becomes smaller than that in the engine. Thus, the upstream pressure P1 of said supercharger 16 becomes larger than the downstream pressure P2, so that flow in said supercharger 16 is limited. Even if superfluous exhaust energy is given to a turbo supercharger 10 by energy corresponding to required supercharging pressure, the supercharging pressure passing through said supercharger 16 is properly restrained while said supercharger 16 serves as an expansion machine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a supercharging device for an engine, and particularly to measures against high supercharging of an engine equipped with a turbo supercharger.

(Prior Art) Conventionally, as shown in Japanese Patent Laid-Open No. 59-150927, for example, a turbine provided in the exhaust passage drives a compressor provided in the intake passage, thereby utilizing exhaust energy to generate intake air. Turbochargers that supercharge fuel are widely known.

By the way, in an engine equipped with such a turbocharger, it is necessary to regulate the maximum boost pressure to avoid an excessive increase in boost pressure. A waste gate passage that bypasses the waste gate passage and a waste gate valve that opens and closes this waste gate passage according to the boost pressure are provided. By letting a part of the pressure into the wastegate passage, the supercharging pressure does not rise to -L.

However, with this, when the engine is running at high speed and under high load,
The energy of the exhaust gas escaping into the strike gate passage was wasted, and there was room for improvement in terms of exhaust energy utilization efficiency.

(Purpose of the Invention) In view of the above circumstances, the present invention has been developed in a J3 engine equipped with a turbo supercharger. The present invention provides an engine turbocharging device that increases engine torque.

(Structure of the Invention) The present invention provides an engine equipped with a turbocharger that supercharges intake air by driving a compressor provided in an intake passage by a turbine provided in an exhaust passage. A blower connected to the output shaft of the engine via a transmission mechanism is provided in the intake passage, and the blower and the engine are connected so that the volumetric flow rate of the blower is smaller than the volumetric flow rate of the engine at least in a high-speed, high-load range. The ratio of the number of circulations is set.

In this configuration, "volume flow 1" means the value obtained by multiplying the volumetric efficiency of the engine by the same number of engine intakes per unit time, and this also applies to the blower.

With this configuration, at least in the high-speed, high-load range of the engine, the upstream pressure of the blower is higher than the downstream utility power, giving expansion work to the blower and transmitting it to the engine, which uses excess energy for supercharging. A recovering effect can be obtained.

(Embodiment) FIG. 1 shows an embodiment of the present invention.
A combustion chamber 3 formed above a piston 2 in a cylinder 1 of the engine has an intake port 5 opened and closed by an intake valve 4 and an exhaust port 7 opened and closed by an exhaust valve 6, and an intake passage is connected to these boats. 8 and an exhaust passage 9 are in communication with each other. Reference numeral 10 denotes a turbo supercharger, which includes a turbine 11 provided in the exhaust passage 9 and a compressor 13 provided in the intake passage 8 and connected to the output shaft 12 of the turbine 11. It is driven to supercharge the intake air.

The exhaust passage 9 is formed with a waste gate passage 14 that bypasses the turbine 11, and the waste gate passage 14 is provided with a waste gate valve 1b that opens and closes a lever passage according to the boost pressure. . As generally known, this waste gate valve 15 is
The maximum supercharging pressure is regulated by adjusting the amount of exhaust gas bypassed to the waste gate passage 14, but in order to reduce the amount of exhaust gas bypass in the high supercharging range compared to conventional methods, The operating conditions for the gate valve 15 are set.

Further, in the intake passage 8 downstream of the compressor 13, a mechanical supercharger 16 such as a Roots blower type is provided as an air blower. This mechanical supercharger 16 has a transmission mechanism 17 consisting of a pulley 18 connected to its rotating shaft, a pulley 20 connected to one output shaft of the engine, and a belt 21 passing between these. Through, engine output shaft 1
9 is connected in an M-motion manner. In the transmission mechanism 17, the rotation speed ratio between the mechanical supercharger 16 and the engine is variable. In other words, as shown in FIG.
117, the effective diameter of each pulley 18.20 is 111
By making it variable, the boolean ratio is variable.

The control section 24 receives signals from the air flow meter 22 and the engine speed sensor 23, and the boolean ratio is controlled via the actuator 25.

Furthermore, the intake passage 8 is provided with a bypass passage 26 that bypasses the mechanical supercharger 16, and this bypass passage 26 has a bypass valve 27 that opens and closes this passage in response to a control signal from the control section 24. is provided.

Reference numeral 28 denotes a throttle valve that adjusts the intake air 6) according to the accelerator operation, and this throttle valve 28 is provided at least upstream of the mechanical supercharger 16, and in the figure, it is provided in the -[flow] direction from the compressor 13. Further, 29 is an intercooler that cools the supercharged air.

The rotation speed ratio between the mechanical supercharger 16 and the engine in this supercharging device is set such that the volumetric flow rate of the mechanical supercharger 16 is smaller than the volumetric flow rate of the engine at least in the high speed and high load range. ing. In other words, if the volumetric efficiency of the mechanical supercharger 16 is ηvp, the same rotational speed is ND, the volumetric efficiency of the engine is ηR8, and the same rotational speed is N, the number of engine cylinders is m and e, then ηVpxNp at least in the high speed and high load range. 〈ηV8×Nexm/2 Therefore, mechanical supercharging! The rotation speed ratio P12 (=NO/No) between fi16 and the engine is PR<(η,).

/ηvp)×(m/2). If such conditions are satisfied, the pressure 1]1 between the compressor 3 and the mechanical supercharger 16 becomes higher than the pressure P2 downstream of the mechanical supercharger 16.

In particular, in this embodiment, the transmission mechanism 17 and the control section 2
4, as shown in FIG.
Yes,! In step 2, the boolean ratio (rotational speed ratio r'F<) is reduced to the extent that the condition F is satisfied, while the pulley ratio is increased below the predetermined engine speed No., and the mechanical supercharger 16 is increased in the low speed range. The downstream pressure P2 is made larger than the hi pressure P1.

Furthermore, the bypass valve 27 is controlled to gradually open at an engine speed that is lower than a predetermined engine speed No. when the engine speed reaches the predetermined engine speed No. The reason why the bypass valve 27 is controlled in this way is to alleviate sudden torque fluctuations when switching the boolean ratio.

The operation of the supercharging device as described above will be explained next.

In a high-speed load range where the turbo supercharger 13 has a supercharging capacity higher than the engine's required supercharging pressure, the volumetric flow rate of the mechanical supercharger 16 becomes smaller than the engine's volumetric flow rate as described above. Since the rotation speed ratio PR is set to , and the upstream pressure P1 of the mechanical supercharger 16 becomes larger than the downstream pressure P2, the flow of supercharged air in the mechanical supercharger 16 is restricted. Become. Follower, turbo supercharger 1
Even if excessive exhaust energy is given to the engine 0 than the energy corresponding to the required boost pressure, the pressure of the supercharged air passing through the mechanical supercharger 16 is moderately suppressed, and the mechanical supercharger 16
The mechanical supercharger 16 functions as an expander, contrary to its original function as a compressor, and thereby gives expansion work to the mechanical supercharger 16. By transmitting this expansion work to the engine via the transmission mechanism 17, excess exhaust energy is recovered as engine driving force for supercharging. Zarani, upper princess expansion S
This also provides the effect of lowering the intake air temperature, which is also advantageous in preventing knocking.

The recovered horsepower HP due to the expansion work in the mechanical supercharger 16 is determined by the expansion efficiency as η, the mechanical efficiency (including the transmission efficiency of the transmission mechanism) as R0, the amount of air i as G1, the gas constant as R1, and the specific heat ratio as , If the temperature upstream of the mechanical supercharger 16 is T1, then 1-I P = ηp e XηpIaxAxB However, △
-G×1Xl-1/75C 8=1-(R2/P1)0 C==(K-1)/. The difference ΔT between the temperature ``1'' upstream of the mechanical supercharger 16 and the temperature downstream is ΔT-('r+/77) (1-(R2/P1
) c) c.

Furthermore, if the rotational speed ratio rR is increased to 1 in the low speed range as in this embodiment, the mechanical supercharger 16 operates as an original compressor in such a range. Therefore, turbocharger 1
In the low speed range where sufficient supercharging cannot be obtained due to the 0, the mechanical supercharger 16 supplements the supercharging.

In the above embodiment, the rotational speed ratio between the mechanical supercharger and the engine is changed in two stages, but the rotational speed ratio may be changed in multiple stages or steplessly.

Furthermore, if the blower (mechanical supercharger in the embodiment) is not expected to assist supercharging at low speeds, the rotational speed ratio may be set constant.

(Effects of the Invention) As described above, the present invention provides a blower that is linked to the engine output shaft downstream of the compressor of the turbocharger, and allows the blower to act as an expander at least in the high speed and high load range. Therefore, at high speed and high load when the turbo supercharger has a supercharging capacity higher than the engine's required supercharging pressure, excess exhaust energy for the supercharging action can be recovered to the engine via the blower, This allows the engine torque to be increased.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the entire device showing one embodiment of the present invention, Fig. 2 is a schematic diagram of the rotation speed ratio control section, and Fig. 3 is a diagram showing the pulley ratio and bypass pulse 1lil control operation in the transmission mechanism. It is an explanatory diagram. 8... Intake passage, 9... Exhaust passage, 10... Turbo supercharger, 11... Turbine, 13... ] Bresser, 16... Mechanical supercharger (blower), 17 ...Transmission mechanism. Patent applicant Mazda Co., Ltd. Agent
Person Patent Attorney Etsu Kotani I1
Patent Attorney Mo 1) Masayuki Patent Attorney
Yasuo Itaya 30 Edgin rotating bed

Claims (1)

[Claims] 1. In an engine equipped with a turbocharger that supercharges intake air by driving a compressor installed in the intake passage by a turbine installed in the exhaust passage, there is a A blower is provided that is connected to the engine through a transmission mechanism, and the rotation speed ratio between the blower and the engine is set so that the volumetric flow rate of the blower is smaller than the volumetric flow rate of the engine at least in a high-speed, high-load range. A supercharging device for engines.