JPS6172859A - Suction heating controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve suction charging efficiency in time of driving at high speed, by installing a separate suction passage provided with an on-off valve interposingly so as to bypass a PTC heater to be installed in another suction passage, while making this on-off valve open at a time when a heater current is more than the specified value. CONSTITUTION:In time of engine (1) running, that whether cooling water temperature Tw detected by a water temperature sensor 26 at a control unit 24 is lower than the specified value Tws or not is discriminated, and when judgment it YES, a switch 21 is closed, energizing a PTC heater with a continuous rating current, and suction preheating is carried out with this heater. Next, on the basis of an on-off signal out of a starter switch 27 after the elapse of the specified time, whether starting is completed or not is discriminated, and in time of engine starting completion, a PTC heater current Ih detected at a current detecting resistor 28 is compared with the specified value Ih1. And, in time of running at high speed to be Ih>=Ih1, feed of the continuous rating current to a solenoid valve 15 takes place, and negative pressure is led into a diaphragm device 13, making a valve element 11 open. With this constitution, suction air is inhaled in the engine without any pressure loss.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an intake air heating control device used for heating the intake air of an internal combustion engine, and in particular to an intake air heating control device using a PTC heater.
It concerns Akane's control device.

Conventional Technology In order to improve the cold startability of diesel engines and reduce white smoke emissions during cold operation, intake air is heated by an intake air heating device installed in the middle of the intake passage, generally called an intake heater. It is well known that heating is effective. Intake air heating devices used for this intake air heating have been proposed in various forms in the past, one of which uses a PTC heater made of a positive temperature coefficient thermistor with a lattice structure, as disclosed in Japanese Patent Laid-Open No. 56-148658. No., Utility Model Publication No. 58-25652.

PTC heaters have a higher degree of freedom in shape than metal heaters, and are often placed across the intake passage in a square lattice or honeycomb shape to obtain ventilation and a large heat exchange surface area (heating surface 1). The plate-shaped heater is formed in a lattice-like shape, that is, a ventilation structure, and the smaller the lattice size is, the larger the heat-generating surface area becomes.

In the above-mentioned intake air heating device, the larger the heat generating surface area of the PTC heater, the more rapidly the intake air is heated. Although this is favorable for reducing
However, due to the increase in the heat generating surface area of the PTC heater, the smaller the lattice size, the more the PTC heater becomes an intake resistance during engine operation, increases the pressure drop in the engine intake system especially during high-speed operation, and reduces the engine output. This may cause a decrease in the temperature.

In order to avoid pressure loss in the engine intake system caused by the PTC heater, a bypass intake passage is provided that bypasses the PTC heater placed across the intake passage, and when the intake air is heated, the bypass intake passage is closed by a shutoff valve and the intake air is heated. Japanese Utility Model Application Publication No. 57-182253 discloses an intake air heating control device configured to open the shutoff valve and cause intake air to flow through the bypass intake passage when the operation is not performed.

Problems to be Solved by the Invention Although the above-mentioned intake air heating control device achieves the intended purpose, this does not mean that the bypass intake passage is always closed when heating the intake air, and that all of the intake air is always kept under PTC. If configured to flow through the heater, a large amount of intake air P can be reduced even during high-speed operation when active intake air heating is not required.
Since the air passes through the TC heater, the power consumption of the PTC heater increases significantly, resulting in wasted power consumption, and at this time, the filling efficiency is significantly reduced due to the intake resistance caused by the PTC heater.

Means for Solving the Problems In view of the above-mentioned problems, intake air heating control according to the present invention]
The device includes a first intake passage having a PTC heater with a ventilation structure arranged in a stepped manner across the intake passage, and a valve provided in parallel with the first intake passage and opening/closing the intake passage in the middle. an intake air heating control device for an internal combustion engine having a second intake passage, the device includes means for detecting a current flowing through the PTC heater, and when the current is below a predetermined value, the valve is driven to close; is characterized in that the valve is driven to open when is equal to or greater than a predetermined value.

Functions and Effects of the Invention Considering the temperature-electrical characteristics of the PTC heater itself, the current flowing through the PTC heater increases as the amount of heat dissipated by the PTC heater increases, or in other words, as the flow rate of intake air passing through the PTC heater increases. Therefore, the current flowing through the PTC heater increases during high-speed operation.

Therefore, as in the intake air heating control device according to the present invention (by controlling the opening and closing of the valve according to the current, the flow rate of the intake air flowing through the PTC heater according to the current is controlled in a feedback control manner, At the same time, the intake flow rate is prevented from increasing excessively, and at the same time, the current flowing through the PTC heater is limited by feedback control, thereby avoiding a significant increase in the power consumption of the PTC heater. By controlling the flow rate of the intake air flowing through the engine, pressure loss in the engine intake system is prevented from increasing due to the PTC heater.

EXAMPLE J The present invention will be described in detail with reference to the accompanying drawings below.

FIG. 1 shows one embodiment of the intake air heating control device according to the present invention. In Figure 1, 1 indicates a diesel engine,
Reference numeral 2 indicates an intake manifold, 3 indicates an intake air heating device, and 4 indicates an air cleaner.

The intake air heating device M3 has a first intake passage 5 and a second intake passage 6 that are provided in parallel with each other.

In the middle of the first intake passage 5, a PTC heater 7 having a lattice structure and having ventilation is provided across the intake passage. A valve element 11 is provided in the middle of the second intake passage 6 to open and close the second intake passage.

The valve element 11 is configured to move by rotation of the valve shaft 10 between a valve open position in which the second intake passage 6 is closed and a valve open position in which communication between the second intake passage 6 and the second intake passage 6 is established. Valve stem 10
A drive lever 12 is mounted at one end and is drivingly connected to a rod 14 of a diaphragm device 13.

The diaphragm device 13 drives the valve element 11 to the closed position when a negative pressure of a predetermined value or more is not introduced into the diaphragm chamber, whereas a negative pressure of a predetermined value or more is introduced into the diaphragm chamber. At times, the valve element 11 is driven into said open position.

The diaphragm chamber of the diaphragm device 13 is connected to the port 4 of the solenoid valve 15 . In addition to port a, the solenoid valve 15 has a negative pressure port b connected to the negative pressure pump 16 and an atmospheric pressure port C opened to the atmosphere, and when energized, port a is connected to negative pressure port b. However, when the power is not energized, port a is connected to port C instead of port B. Therefore, when the solenoid valve 15 is energized, a negative pressure equal to or higher than a predetermined value is introduced into the diaphragm chamber of the diaphragm device 13, the valve element 11 is located in the open position, and the solenoid valve 15 is energized. When not, atmospheric pressure is introduced into the diaphragm chamber of the diaphragm device 13 and the valve element 11 is in the open position.

The PTC heater 7 is configured to be selectively supplied with current from a battery power source 20 via a heater electric switch 21 and a current detection resistor 28.

Control of energization to the solenoid valve 15 and opening/closing of the heater electric switch 21 and the electric switch 23 of the indicator lamp 22 are performed by an electric control device 2 including a microcomputer.
4, the process is carried out according to a flowchart as shown in FIG.

The flowchart shown in FIG. 2 starts when the engine key is inserted into the keyhole and the key switch 25 is turned on.

In the first step 1, it is determined whether the engine cooling water temperature Tw detected by the water temperature sensor 26 is lower than a predetermined value wITwset. When TW≦Jwset, that is, at cold start, proceed to step 2;
If W≦T wset is not satisfied, the process proceeds to step 6.

In step 2, the heater electric switch 21 is closed and the lamp electric switch 23 is closed. As a result, the PTC heater 7 is energized and the PTC
The heater 7 generates heat and the indicator lamp 22 lights up to notify the driver that the intake child is heating up. Note that, at this time, since the electromagnetic valve 15 is not energized, the valve element 11 is located at the valve-closed position and closes the second intake passage.

After step 2, proceed to step 3, and in step 3, the preheat time 1 before starting and the afterheat time t2 after starting are determined according to the cooling water temperature 1"w at this time. Both the preheat time t1 and the afterheat time [2] are set longer as the cooling water mW is lower.

After step 3, proceed to step 4, and in step 4, after the heater electric switch 21 is closed,
That is, it is determined whether a predetermined time tl has elapsed since energization of the PTC heater 7 was started. Predetermined time 1. If the period of time has not elapsed, this step 4 is executed repeatedly, and when the predetermined period of time has elapsed, the next step 5 is executed.
Proceed to.

In step 5, the lamp electric switch 23 is opened. As a result, the indicator lamp 22 turns off, and the driver is notified that the intake air preheating (preheating) has been completed. After step 5, proceed to step 6.

In step 6, it is determined from the on-off signal of the starter switch 27 whether or not starting of the diesel engine by the starter has been completed. If the inter-machine start is not completed, this step 6 is repeatedly executed, and when the engine start is completed, the process proceeds to the next step 7.

In step 7, it is determined whether the electric heater switch 21 is closed, that is, whether the PTC heater 7 is energized.

When the heater electric switch 21 is closed, the process proceeds to step 8, whereas when the heater electric switch 21 is open, the process proceeds to step 14.

In step 8, it is determined whether the current Ih of the PTC heater 7 detected by the current detection resistor 28 is larger than a predetermined value 1hl. (2) When h≧Ih+, the process proceeds to step 9; on the other hand, when Ih≧Ih+, the process proceeds to step 11. The current Ih of the PTC heater 7 increases the heat dissipation amount of the PTC heater 7, that is, the PTC heater 7
Since I increases with the increase in the flow rate of intake air passing through
When h≧l11+, it is during high-speed operation that does not require active intake air heating.

In step 9, the electromagnetic valve 15 is energized. As a result, the valve element 11 is opened during high-speed operation even during intake air heating after engine startup, that is, during afterheating.
Most of the intake air flows through the second intake passage 6. This prevents the pressure drop in the engine intake system from increasing, and also prevents a large amount of intake air from flowing through the PTC heater 7, thereby avoiding an increase in wasteful power consumption in the PTC heater 7.

After step 9, proceed to step 10. In step 10, it is determined whether a predetermined time t2 has elapsed since the start of the diesel engine was completed. Predetermined time t2
If the predetermined time 12 has not elapsed, the process returns to step 8, whereas if the predetermined time 12 has elapsed, the process proceeds to the next step 13.

In step 11, it is determined whether the current h of the FT and C heaters 7 is smaller than a predetermined value 1112. Note that the predetermined value 1112 is a value smaller than the predetermined value 1h+.

When rh≦Ihg, the process proceeds to step 12; on the other hand, when Ih≦■]12, the process proceeds to step 10.

In step 12, energization to the solenoid valve 15 is stopped. As a result, when the engine is not operating at high speed, the valve element 11 is closed and the second intake passage 6 is closed again.

In step 13, the heater electric switch 21 is opened. As a result, the power supply to the PTC heater 7 is stopped, and the afterheating ends.

After step 13, proceed to step 14, and step 14
At this time, the electromagnetic valve 15 is energized. As a result, after the intake air heating is completed, the valve element 11 is located at the valve open position, and the second intake passage 6 is spaced in order to prevent the pressure drop in the engine intake system from increasing.

Step 140 Next, proceed to step 15, step 15
When the key switch 25 is released, it is determined whether or not the key switch 25 is in the on state. When the key switch 25 is in the on state, this step 15 is repeatedly executed, whereas when the key switch 25 is not in the on state, that is, when the engine is stopped, the process proceeds to step 16.

In step 16, energization to the solenoid valve 15 is stopped.

- By controlling the opening and closing of the valve element 11 according to the flowchart as described above, even during intake air heating, during high-speed operation when the flow rate of intake air passing through the PTC heater 7 increases as the intake air amount increases. , the flow rate of the intake air passing through the PTC heater 7 is restricted, and the intake air flows bypassing the PTC heater 7, thereby avoiding an increase in wasteful power consumption in the PTC heater 7, and increasing the pressure drop in the engine intake system. Things are prevented.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited thereto.
It will be apparent to those skilled in the art that many other embodiments are possible within the scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing one embodiment of the intake air heating control device according to the present invention, and FIG. 2 is a flowchart showing the operation procedure of the intake air heating control device according to the present invention. 1...Diesel engine, 2...Intake manifold. 3... Intake air heating device, 4... Air cleaner, 5...
- First intake passage, 6... Second intake passage, 7...
PTC heater, 10... Valve shaft, 11... Valve element, 1
2... Drive lever, 13... Diaphragm device, 1
4...Rod. 15...Solenoid valve, 16...Negative pressure pump, 20...
Battery power supply, 21... Electric switch for heater, 22
...Indicator lamp, 23...Lamp electric switch. 24...Control device, 25...Key switch, 26.
・・Water temperature sensor, 27・・Starter switch, 28・
・・Resistor for current detection

Claims (1)

[Claims] PT with ventilation structure installed across the intake passageway
An intake air heating control device for an internal combustion engine, comprising a first intake passage having a C heater, and a second intake passage provided in parallel with the first intake passage and having a valve in the middle for opening and closing the intake passage, It has a means for detecting the current flowing through the PTC heater, and when the current is below a predetermined value, the valve is driven to close, and when the current is above a predetermined value, the valve is driven to open. Intake heating control device.