JPH0739689Y2 - Turbo heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a turbo heater that directly or indirectly uses discharge air from a blower driven by an exhaust turbine as a heat source for heating a vehicle compartment or a heat source for heating engine intake air.

[Conventional technology]

The turbo heater, which heats the air by using a blower driven by an engine exhaust turbine and introduces the hot air from the blower into the passenger compartment for heating, can generate hot air immediately after starting, which is advantageous when used as a rapid heating device. Is.
Further, if the high temperature blower discharge air is introduced into the engine intake air, the intake air heating can shorten the engine warm-up time.

This turbo heater can be used as an auxiliary heating means until a normal heating device using engine cooling water can be used especially when it takes time for the cooling water temperature to rise after engine start in a cold region. .

As this type of turbo heater, there is one described in Japanese Patent Laid-Open No. 1-156126. The turbo heater disclosed in the publication has an opening / closing valve in the engine exhaust passage and an exhaust bypass passage bypassing the opening / closing valve, and a blower compressor coaxially connected to an exhaust turbine installed in the exhaust bypass passage to provide air inside the vehicle interior. Is used for rapid heating by introducing high-temperature discharge air into the passenger compartment, and the above-mentioned on-off valve opens when the temperature of the cooling water rises and the normal heating system becomes available to operate the turbo heater. It is supposed to stop.

[Problems to be solved by the device]

The turbo heater disclosed in JP-A-1-156126 is effective as a quick heating device when the engine is cold started, but exhaust resistance is generated during operation of the turbo heater because the blower is driven by the exhaust turbine provided in the engine exhaust passage. There was a problem affecting the engine output. That is, the exhaust gas flow rate of the engine increases with the engine load as well as with the engine speed. Further, the flow rate of exhaust gas that can pass through the exhaust turbine increases according to the rotational speed of the turbine, but the exhaust turbine drives the blower and receives a load proportional to the cube of the rotational speed. Therefore, when the exhaust gas flow rate of the engine increases, the turbine rotational speed increases in order for the flow rate to pass through the exhaust turbine, and the turbine inlet pressure is increased until sufficient work is generated to drive the blower at that rotational speed. That is, the back pressure of the engine exhaust will increase. Therefore, when the vehicle is running while the turbo heater is operating, when the engine load increases due to starting or acceleration, the back pressure of the exhaust system suddenly rises and the engine output does not increase as expected, and it tends to take time to start and accelerate. Will come out. Moreover, since the turbo heater operates in a state where the engine cooling water temperature is low, that is, in a state where warm-up is insufficient, the above-mentioned output decrease is large, and there is a problem that drivability, so-called drivability is impaired.

The present invention has been made in view of the above problems, and an object thereof is to provide a turbo heater in which drivability deterioration during operation is minimized, and yet the original heating and intake air heating effects are not deteriorated.

[Means for Solving the Problems]

The present invention provides a turbocharger in which an exhaust switching valve is provided in an engine exhaust passage, a bypass passage connecting an exhaust switching valve upstream side and a downstream side of the exhaust passage is formed, and a blower driving exhaust turbine is installed in the bypass passage. In the heater, the exhaust switching valve is opened / closed according to the engine speed and the engine load, and the valve closing speed is set lower than the valve opening speed.

[Action]

With the above structure, the present invention quickly opens the switching valve when the engine output is required for starting, acceleration, etc., stops the operation of the turbo heater, and reduces the back pressure of the engine exhaust system to reduce the engine output. When the turbo heater is restarted after the acceleration is completed and the normal operation state is restored and the turbo heater is restarted, the back pressure is gradually increased when the turbo heater is operated by setting the operation speed of the switching valve to be slower than when it is opened. Since it is increased, there is no sudden drop in engine output.

〔Example〕

 The present invention will be described below with reference to illustrated embodiments.

FIG. 1 is an overall schematic view of an embodiment of a turbo heater according to the present invention, in which 1 is an engine, 2 is an intake passage, 3 is an exhaust passage, and 4 is a turbo heater. Is equipped with an air cleaner 5.

The turbo heater 4 includes an exhaust turbine 7 and a blower 8 which are connected to each other via a rotary shaft 6. An exhaust switching valve A is arranged in the exhaust passage 3, and a bypass passage 9 that connects the exhaust passage 3 upstream of the exhaust switching valve A and the exhaust passage 3 downstream of the exhaust switching valve A is connected to the exhaust passage 3. The exhaust turbine 7 of the turbo heater 4 is arranged in the bypass passage 9,
The exhaust turbine 7 is rotationally driven by the exhaust gas flowing in the bypass passage 9. On the other hand, the air intake passage 10 of the blower 8 of the turbo heater 4 is connected to the air cleaner 5 via the auxiliary intake passage 11 arranged so as to surround the exhaust passage 3 in this embodiment, and the discharge passage 12 of the blower 8 is blocked. It is connected to the passenger compartment 14 via a valve B. If the engine is connected to the engine intake passage 2 instead of the discharge passage 12 to the vehicle compartment 14, intake air heating can be performed, and if it is branched on the upstream side of the shutoff valve B and connected to the intake passage 2, vehicle interior heating and intake air heating can be performed. You can do both. In the present embodiment, only the case of heating the passenger compartment will be described, but the following description is also the same for the case of performing only the intake air heating and the case of using the intake air heating together.

The turbo heater 4 is considerably smaller than a turbocharger for supercharging that is generally used, and its sole purpose is to raise the air temperature, and it is the most efficient air heater during idling operation or constant speed operation. Is set to stir.

The exhaust switching valve A is connected to a corresponding negative pressure diaphragm device 16, and the negative pressure chamber 19 of the negative pressure diaphragm device 16 is connected to a negative pressure source such as an engine vacuum pump via an electromagnetic switching valve A ₀ that can communicate with the atmosphere. It When the negative pressure chamber 19 is opened to the atmosphere by the switching action of the electromagnetic switching valve A _0, the exhaust switching valve A is opened, and when the negative pressure chamber 19 is connected to the negative pressure source, the exhaust switching valve A is closed. . A valve closing delay device 40, which is a feature of the present invention, is provided between the switching valve A ₀ and the negative pressure chamber 19 as described later in detail.

A heater 23 for utilizing engine heat generation is arranged in the passenger compartment 14. The cooling water whose temperature has been raised in the engine 1 is supplied to the engine heat generation utilizing heater 23 through the cooling water supply conduit 24, and the cooling water whose temperature has dropped due to heat being released into the vehicle interior 14 is returned to the cooling water return conduit. Returned to Engine 1 via 25.

The shutoff valve B includes a negative pressure diaphragm device similar to the switching valve A and an electromagnetic switching valve B _0, and is opened and closed by switching between a negative pressure source and atmospheric pressure by the electromagnetic switching valve B ₀ .

The electronic control unit (ECU) 51 consists of a digital computer and is connected to each other by a bidirectional bus 52.
M (read only memory) 53, RAM (random access memory) 54, CPU (microprocessor) 55, input port 5
6 and output port 57.

At the input port 56, a water temperature sensor 26 for detecting the cooling water temperature, a fuel injection pump control rack position sensor 31 for detecting the engine load, an engine speed sensor
30 are connected via A / D converters, respectively, while electromagnetic switching valves A ₀ and B ₀ are connected to the output port 57 via drive circuits D, respectively.

Next, an example of the control operation of the turbo heater of the present invention will be described. First, when the engine is started, the ECU 51
The cooling water temperature T is read from the water temperature sensor 26 via 6 and T
Is lower than the set value T ₀ and the passenger compartment heater switch is turned on, the electromagnetic switching valves A ₀ and B ₀ are output via the output port 57.
, The exhaust switching valve A is closed, and the hot air cutoff valve B is opened. When the exhaust switching valve A is closed, exhaust gas from the engine flows through the bypass passage 9 to drive the exhaust turbine 7 to rotate. As a result, the blower 8 discharges the hot air into the discharge passage 12, and this high-temperature air is supplied to the passenger compartment through the shutoff valve B that is open, and quickly heats the passenger compartment.

Conversely, if the cooling water temperature T exceeds T ₀ while the turbo heater is operating or the heater switch is turned off, the ECU
Reference numeral 51 indicates that the exhaust switching valve A is opened to prevent the exhaust gas from the engine from flowing into the bypass passage 9 to stop the turbo heater and the shutoff valve B is closed to close the compartment 14 and the blower discharge passage.
12 and shut off. When the cooling water temperature T is equal to or higher than the set value T ₀ and the heater switch is ON, the ECU 51 activates the engine heat generation use heater 23 at the same time as the above operation, and switches the heating of the vehicle compartment to the engine heat generation use heater 23.

Therefore, when the cooling water temperature T is lower than the set value T ₀ and the vehicle travels while using heating, the exhaust resistance increases as described above, and the output torque becomes insufficient at the time of starting and sudden acceleration, resulting in drivability. It may get worse.

In order to prevent this, the present invention operates the exhaust switching valve A by the ECU 51 based on the engine speed and the engine load, and when the engine output is required for starting or accelerating the vehicle, the exhaust switching valve A is used. The valve is opened promptly to reduce the back pressure of the engine exhaust system.

The exhaust switching valve A is opened and closed based on the relationship between the engine load (fuel pump rack opening) L and the engine speed N shown in FIG. In other words, the ROM 53 of the ECU 51 has a second
The function shown in the figure is built in, and the CPU 55 of the ECU 51 reads the engine load L and the engine speed N from the fuel injection pump control rack position sensor 31 and the engine speed sensor 30 through the input port 56, respectively. Whether the exhaust switching valve A needs to be opened or closed is determined from the function shown in FIG.

A range surrounded by a broken line I-II-III-IV in FIG. 2 is a turbo heater operating region, that is, a region in which the exhaust switching valve A is closed, and the engine operation is performed by increasing the engine load L or the engine speed. When the condition deviates from the above area
The CPU 55 initiates a valve opening signal through the output port 57 and switches the electromagnetic switching valve A ₀ through the drive circuit D to open the exhaust switching valve A. Further, when starting and acceleration have been completed and the operating condition has returned to the above range, the exhaust switching valve A is closed and the turbo heater is operated in the opposite manner. II-II in FIG.
The line I corresponds to the allowable back pressure increase due to an increase in engine load, and is represented by a substantially constant load in the engine middle speed range regardless of the engine speed. Further, the III-IV line represents the allowable value of the back pressure increase with respect to the increase of the engine speed, and shows that as the engine load increases, the limit value is reached at the lower speed.

FIG. 3 is a flowchart showing the above control of the turbo heater. In the figure, step 301 is a judgment as to whether or not the cooling water temperature T is lower than a set value T _{0. If} the cooling water temperature is lower than T ₀ , it is judged at step 302 whether or not the heater switch is ON, and it is ON. If so, the routine proceeds to step 303. At step 303, it is judged whether or not the engine load and the rotational speed are in the turbo heater operating region of FIG. 2, and if they are within the operating region, the routine proceeds to step 304, where the switching valve A is set. The valve is closed, the turbo heater is activated, the shutoff valve B is opened, and hot air is sent to the passenger compartment. On the other hand, if it is determined in step 303 that the turbo heater is out of the operating region, the flow advances to step 305 to open the switching valve A, stop the turbo heater, and close the shutoff valve B. When the heater switch is off in step 302, the process similarly proceeds to step 305.

If the cooling water temperature T rises and exceeds the set value T ₀ , the process proceeds from step 301 to step 306, and if the heater switch is ON, the engine heat utilization heater is operated in step 307, and then the heater switch is turned OFF. For step 305 directly
Go to and stop the turbo heater.

As described above, by opening and closing the exhaust valve A according to the engine load and the number of revolutions, it becomes possible to secure the output during acceleration and the like even when the turbo heater is in use. However, the valve opening speed of the exhaust valve A is preferably set as high as possible, but the valve closing speed is preferably set slower than the valve opening speed. That is, the exhaust valve A is opened when the driver's vehicle demands acceleration, so it is preferable that the exhaust switching valve A is quickly opened to reduce the back pressure, but the acceleration or the like is ended. When returning the turbo heater, if the valve closing speed of the switching valve A is fast, the back pressure increases at once and the engine torque sharply decreases. For this reason, the vehicle will decelerate more than the driver expected from the accelerator return amount. The driver steps on the accelerator again to correct this, but the operating condition enters the turbo heater OFF region shown in FIG. 2 for this reason, the switching valve A is opened again, the engine torque increases, and the vehicle accelerates rapidly. . Since the driver further restores the accelerator without correcting it, the above-mentioned operation is repeated, and a so-called busy opening / closing phenomenon occurs in which the accelerator is operated and the exhaust switching valve A is frequently opened / closed, which deteriorates drivability. To do.

In order to prevent this, it is conceivable that a throttle is provided in the negative pressure passage between the diaphragm device 16 and the electromagnetic switching valve A ₀ to delay the operation speed of the switching valve A. Since the valve opening speed of A also becomes slow, the output increase at the time of acceleration is delayed, which causes “wobble”, which is not preferable.

The present invention is characterized in that a valve closing delay device 40 is provided in the negative pressure passage so that the valve opening speed of the switching valve A is not affected and the valve closing speed is slower than the valve opening speed.

The valve closing delay device 40 has, for example, a structure in which a check valve 43 is provided in a main negative pressure passage 44 and a throttle 42 is provided in a negative pressure bypass passage 45 that bypasses the check valve 43, as shown in FIG. .

That is, when the electromagnetic switching valve A ₀ is opened to the atmosphere, air flows from the check valve 43 through the main negative pressure passage 44 into the negative pressure chamber 19, so that the pressure in the negative pressure chamber 19 rapidly rises. The exhaust switching valve A opens at a high speed. On the other hand, when the negative pressure source whose electromagnetic switching valve A ₀ is switched is connected, the air in the negative pressure chamber 19 cannot pass through the check valve 43, but passes through the throttle 42 and the negative pressure bypass passage 45.
The pressure in the negative pressure chamber 19 gradually decreases as the pressure changes from the negative pressure source to the negative pressure source, and the exhaust switching valve A is closed at a slower speed than when the valve is opened.
Therefore, the back pressure of the engine also gradually increases, a sudden decrease in torque does not occur, and the driver's accelerator operation can follow the decrease in torque, so the so-called busy opening / closing does not occur.

[Effect of device]

The present invention uses the exhaust switching valve that turns the turbo heater ON / OFF according to the engine load and engine speed, and the valve closing speed (turbo heater startup operation speed) is slower than the valve opening speed. Produce the effect of.

That is, when the engine output is required for acceleration or the like, the turbo heater can be quickly stopped to secure the output, and when the acceleration is completed and the normal operation state is restored, the turbo heater is gently activated. Therefore, the engine torque does not drop sharply and the so-called busy opening / closing phenomenon does not occur. For this reason, the drivability is improved, the life of each part is prevented from being shortened due to the busy opening / closing, and the turbo heater's heating and intake air heating effects are increased because the turbo heater's small start-stop does not occur.

[Brief description of drawings]

FIG. 1 is an overall schematic view of an embodiment of a turbo heater according to the present invention, FIG. 2 is a view showing a relationship between an engine load and a rotational speed, and opening / closing of an exhaust switching valve, and FIG. 3 is an operation control of the turbo heater. A flow chart, FIG. 4, is a schematic diagram showing the construction of the valve closing delay device of the present invention. 1 ... Engine, 3 ... Exhaust passage, 4 ... Turbo heater, 7 ...
Exhaust turbine, 8 ... Blower, 9 ... Bypass passage, A ... Exhaust switching valve, 14 ... Cabin, 30 ... Engine speed sensor, 31 ...
Load sensor, 40 ... valve closing delay device, 51 ... electronic control unit,

Claims (1)

[Scope of utility model registration request] 1. An exhaust switching valve is provided in an engine exhaust passage, and a bypass passage connecting an exhaust switching valve upstream side and a downstream side of the exhaust passage is formed. An exhaust turbine for driving a blower is provided in the bypass passage. In the installed turbo heater, the exhaust switching valve is opened / closed according to the engine speed and the engine load, and the valve closing speed is set lower than the valve opening speed.