JPS6158917A - Intake cooler of engine with supercharger - Google Patents

Abstract

PURPOSE:To improve acceleration responsive property by providing a bypass path for bypassing a intake cooler of an engine with a supercharger to pass the intake through the bypass path only for a predetermined time in acceleration. CONSTITUTION:Since pressurized air from a supercharger 15 has high temperature it is sucked into a cylinder 5 after said air is cooled by a intake cooler 14. Since it takes time for filling air in the intake cooler at accelerating an engine, change-over valves 18, 20 are changed over to pass air through a bypass path 13. These valves 18, 20 are driven by actuators 17, 19. A control unit 22 detects 33 the accelerated condition to immediately drive the actuators 17, 19 and pass air through the bypass path 13. However, after a predetermined delay, the valves 18, 20 are changed over to pass again air through the intake cooler 14. During this delay the intake cooler is filled with air so that sufficient air in the acceleration is ready for being supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention consists of 1. A supercharger equipped with a supercharger in an intake passage, and a cooling passage equipped with an intake air cooler and a bypass passage that bypasses the intake air cooler in parallel with each other in the intake passage on the downstream side of the supercharger. The present invention relates to an intake air cooling device for an engine, and more specifically, to one that improves and obtains acceleration response during engine acceleration.

(Prior art) Many engines with superchargers are equipped with an intake air cooler (intercooler), which generally prevents overcooling during low loads. For this reason, the intake passage on the downstream side of the supercharger is provided with a cooling passage equipped with an intake air cooler and a bypass passage that bypasses the intake air cooler in parallel with each other (Japanese Patent Laid-Open No. 57-195820 In other words, during low loads when the intake air temperature does not rise much, intake air is supplied to the engine through the bypass passage, while during high loads when the boost pressure increases and the intake air temperature becomes high, the intake air temperature is supplied to the engine through the cooling passage. After lowering the intake air, it is supplied to the engine.

In such an intake air cooling system for a supercharged engine, intake air is supplied through the cooling passage even when the engine accelerates, but the response during engine acceleration, that is, the acceleration response becomes poor. The problem arises. To explain this point in detail, when the intake air is supplied through the bypass passage in a low-load operation state, and when you try to accelerate by depressing the accelerator greatly, that is, when the load is high, the intake air flow is cooled from the bypass passage. However, since the capacity of the intake air cooler is quite large, the intake air fills this large capacity intake air cooler before being supplied to the engine. The increase in boost pressure was delayed by the time required for charging, resulting in poor acceleration response.

In particular, if the supercharger is a turbocharger that is driven by exhaust energy, the supercharger itself has a considerable time lag, so when combined with the time lag of the supercharger, the acceleration response becomes even worse. Become.

(Object of the invention) The present invention has been made in consideration of the above circumstances, and
An object of the present invention is to provide an intake air cooling device for a supercharged engine that is equipped with an intake air cooler and can improve acceleration response during engine acceleration.

(Structure of the Invention) In order to achieve the above-mentioned object, one aspect of the present invention is to provide a time delay in switching from the intake air supply through the bypass passage to the intake air supply through the cooling passage.

Specifically, a supercharger is disposed in the intake passage, and
The present invention is based on an intake air cooling system for a supercharged engine in which a cooling passage including an intake air cooler and a bypass passage bypassing the intake air cooler are provided in parallel with each other on the downstream side of the supercharger.

load detection means for detecting a load on the engine; a first intake flow state for closing the upstream and downstream cooling passages of the intake air cooler to supply intake air to the engine through the bypass passage; and a switching valve device for switching between a second intake flow state and a second intake flow state for supplying intake air.

Switching control means receives an output from the load detection means and controls the switching valve device to bring the first intake flow state into the first intake flow state when the load is low and to put the second intake air flow state into the second intake flow state when the load is high. The switching control means includes a delay means for causing a time delay in switching from the first intake flow state to the second intake flow state.

With this configuration, at least when the engine is initially accelerated, the delay means continues the intake air supply through the bypass passage for a predetermined period of time, and as a result, the supercharging pressure increases quickly, resulting in excellent acceleration response. It becomes something.

(Example) Examples of the present invention will be described below based on the attached drawings.

In Fig. 1, l is the engine body, which consists of the cylinder block 2, the cylinder head 3, and the cylinder block z.
A combustion chamber 5 is formed by a piston 4 which is slidably inserted into the combustion chamber 5.
The piston 5 is of a reciprocating type, and the reciprocating movement of the piston 5 rotates a crankshaft (not shown). The combustion chamber 5 is opened with an intake boat 6 and an exhaust port 7 formed in the cylinder head 3, respectively. It is designed to open and close at well-known timing in synchronization with

An intake passage 11 extending from an air cleaner 10 is connected to the intake boat 6. The intake passage 11 has a cooling passage 12 and a bypass passage 13 parallel to each other, and an intake air cooler 14 is connected to the cooling passage 12. It is arranged. In this way, the cooling passage 1z and the bypass passage 13 are parallel to each other.
Of the intake passage 11, the part upstream from the upstream branch X between the inner passages 12 and 13 is designated by reference numeral 11a as an upstream common passage, and the downstream branch between the inner passages 12 and 13 is indicated by reference numeral 11a. The portion downstream of Y is designated by the reference numeral 11b as a downstream common passage.

A compressor wheel 15a of a supercharger (turbocharger in the embodiment) 15 is disposed in the upstream common passage 11a, and a throttle valve 16 is disposed in the downstream common passage 11b.

Further, a switching valve 18 driven by an actuator 17 is disposed at the upstream branch part X, and this switching valve 18
At the position shown by the solid line in FIG. 1 where the upstream side of the cooling passage 12 is closed, the intake air is directed to the bypass passage 13 and at the position shown by the dashed line in FIG. 1 where the upstream side of the bypass passage 13 is closed. has the function of causing intake air to flow toward the cooling passage 12. An on-off valve 20 driven by an actuator 19 is disposed at the downstream end of the cooling passage 12. The switching valve 18 and the on-off valve 20 constitute the switching valve device of the present invention, and close the cooling passages 12 on the upstream and downstream sides of the intake air cooler 14 so that the intake air passes through the bypass passage 13. The supplied first intake flow state (solid line position in Figure 1),
A second intake flow state in which the cooling passages 12 on the upstream and downstream sides of the intake air cooler 14 are both opened and the bypass passage 13 is closed, and intake air is supplied through the cooling passages 12 (position shown by the dashed-dotted line in FIG. 1). ) and can be taken.

On the other hand, a turbine wheel 15b of the supercharger 15 is disposed in the middle of the exhaust passage 21 connected to the exhaust boat 7, and the exhaust energy is used to generate the turbine wheel 15b.
When the compressor wheel 15a is rotated, the compressor wheel 15a is rotated via the rotating shaft 15c, thereby performing charging.

Reference numeral 22 in FIG. 1 denotes a control circuit, which constitutes switching control means for controlling the operation of the switching valve 18 and the on-off valve 20. This control circuit 22 receives a signal from an intake negative pressure sensor 23 that detects the intake pressure on the downstream side of the throttle valve 16, that is, the engine load.
It is now output to .

As shown in FIG. 2, the control circuit 22 includes a first comparison circuit 24 to which the signal A from the intake negative pressure sensor 23 is input, an m1 reference value setting circuit 25, an integration circuit 26, and a second comparison circuit. 27, a second reference value setting circuit 28, a drive circuit 29 for outputting to both actuators 17 and 19, and a reset circuit 30 are provided, and signals B to F are outputted from each circuit 24 to 28. (See also Figures 3(a) to 3('d)).

Each of these circuits 24 to 29 will be explained, and the drive circuit 29 is as shown in FIG. 3(d).

When it does not receive the signal F (rising signal) from the second comparison circuit 27, it drives both actuators 17 and 19 so as to be in the first intake flow state, and also receives the signal F from the second comparison circuit z7. At times, both actuators 17 and 19 are driven so as to enter the second intake flow state. Further, the first comparison circuit 24 and the first reference value setting circuit 25 are for determining whether to switch to the first intake flow state or the second intake flow state, that is,
It is used to determine whether the load is lower or higher than the reference load. Furthermore, the integration circuit 26, the second comparison circuit 27, and the second reference value setting circuit 28 are configured to control the delay time when switching from the first intake flow state to the second intake flow state at the time of transition from low load to high load. The reset circuit 30 is used to return the integrating circuit z6 to its initial state.

Assuming the above, when the signal A corresponding to the intake pressure from the intake pressure sensor 23 is input to the first comparison circuit 24,
It is compared whether this intake pressure is larger than the reference intake pressure (signal B) set by the first reference value setting circuit 25 (see FIG. 3(a)).

When the intake pressure is larger than this reference intake pressure, this larger amount is outputted as a signal C (see # in FIG. 3(b)), and this signal C is successively integrated by the integrating circuit 26. The signal C integrated by this integrating circuit 26 is
The integrated signal is input to the second comparison circuit 27 as a signal, and the reference signal E from the second reference value setting circuit 28 is combined with the integrated signal.
are compared by the second comparison circuit 27 (see FIG. 3(
C)), and in this second comparison circuit 27, when the signal from the integration circuit 26 becomes larger than the reference signal E, that is, after a delay of time Δt from the start of integration,
The signal F is outputted to the drive circuit 29 as described above. In addition,
The reset circuit 30 receives the output from the comparison circuit 24 (signal C
) disappears (when the load becomes low), the integrating circuit 26 is reset.

As is already clear from the above description of the control circuit 22, when the intake pressure is lower than the reference signal B and the load is low, the signal F is not output from the second comparator circuit 27 to the drive circuit 29, so that the first intake flow state is Therefore, the intake air is supplied to the engine body 1 without passing through the cooling passage 12 (intake air cooler 14), that is, while being prevented from overcooling.

Of course, at this low load, there is no resistance effect from the intake air cooler, which is preferable in terms of reducing intake resistance.

Furthermore, when the intake pressure is higher than the reference signal B and the load is high, the second comparison circuit 27 outputs the signal F to the drive circuit 29, so that the second intake flow state is established as described above. As a result, the intake air is cooled by the intake air cooler 14, and an increase in intake air temperature is prevented. Even if the low load is switched to the high load, the switching from the first intake flow state to the fiS2 intake flow state is delayed by the aforementioned delay time ΔE. The supercharging pressure is quickly increased without the time lapse required to fill the intake air cooler 14, resulting in excellent acceleration response.

In the above embodiments, the case where a turbocharger was used as a supercharger was explained, but as a supercharger, the engine main body l
An appropriate device such as a supercharger or a complex mechanically driven by the power source may be adopted. Furthermore, since the on-off valve 20 is for preventing intake air that has passed through the bypass passage 13 from flowing back toward the intake air cooler 14 during acceleration, a check valve may be used instead of the on-off valve 20. Alternatively, the engine load may be detected by the opening degree of the throttle valve 16.

(Effects of the Invention) As is clear from the above description, the present invention improves acceleration response during engine acceleration while preventing overcooling of the intake air during low loads and increasing the temperature of the intake air during high loads. be able to.

[Brief explanation of drawings]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. FIG. 2 is a circuit diagram showing details of the control circuit. FIGS. 3(a) to 3(d) are diagrams showing the control contents of the control circuit shown in FIG. g2. 1: Engine body 11: Intake passage 11a: Upstream common passage 11b: Downstream common passage 12: Cooling passage 13: Bypass passage 14: Intake air cooler 15: Supercharger 16: Throttle valve 17: 19: Actuator 18 :Switching valve 20:Opening/closing valve 222Control circuit 23:Intake pressure sensor 'yl'J Figure 2Figure 3

Claims (1)

[Claims] (1) A supercharger is disposed in the intake passage, and on the downstream side of the supercharger, a cooling passage equipped with an intake air cooler and a bypass passage that bypasses the intake air cooler are arranged in parallel with each other. The intake air cooling device for a supercharged engine is provided with a load detection means for detecting engine load, and cooling passages on the upstream and downstream sides of the intake air cooler are closed and the cooling passage is passed through the bypass passage to the engine. a switching valve device for switching between a first intake flow state in which intake air is supplied and a second intake flow state in which intake air is supplied through the cooling passage; switching control means for controlling the first intake air flow state when the load is low and switching the intake air flow state from the first intake flow state to the second intake air flow state when the load is high; An intake air cooling device for a supercharged engine, comprising a delay means for causing a time delay in switching to the second intake air flow state.