JPS6316858Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an intake air heating device for an internal heat engine, and particularly for diesel engines, to improve startability and reduce white smoke emissions when the engine is cold. This relates to an intake air heating device that heats intake air for the purpose of heating intake air.

<Prior Art> In diesel engines used in vehicles such as automobiles, starting during a cold start is difficult due to the fact that the intake air temperature does not rise to a temperature that will self-ignite the fuel with only intake air compression. When the engine is cold, a large amount of white smoke is emitted due to incomplete combustion.For this reason, in this type of diesel engine, an electric heater installed in the middle of the intake passage is used during cold starts and when the engine is cold. BACKGROUND ART Conventionally, it has been considered to perform so-called intake air heating, in which the air taken into a diesel engine is combusted.

<Problems to be solved by the invention> Intake air heating using an electric heater is performed to improve the startability of a diesel engine, and is performed prior to starting the engine by the starter, thereby pre-heating the intake air in the intake passage. The engine performs combustion, and in order to shorten the waiting time for starting the engine, it is necessary to use an electric heater with a large heat generation capacity so that the intake air heating can be performed quickly. However, since electric heaters with a large heat generation capacity consume a large amount of power, an electric heater with a relatively large heat generation capacity, which is effective in improving engine startability, is incorporated into the intake air heating device and is used not only when starting the engine but also when the engine starts. If activated to prevent white smoke during the warm-up process after startup,
Depending on the temperature state (warm-up state) of the engine at that time, excessive intake air heating may occur, which not only reduces the intake efficiency of the diesel engine but also causes wasted power consumption, and the power consumption of the electric heater. This may cause the battery power supply to lose its power balance.

This invention quickly heats the intake air to improve starting performance, shortens the startup waiting time especially when the engine is cold, and heats the intake air to prevent white smoke after starting without wasting power. The purpose is to provide an intake air heating device that performs properly.

<Means for Solving the Problems> According to the present invention, the above-mentioned purpose is to provide a first electric heater provided in the middle of the intake passage and having a first heat generating capacity; and a second electric heater having a second heat generation capacity smaller than the first heat generation capacity, and a control means for controlling energization to the first and second electric heaters, the control means for starting the internal combustion engine. Before starting, at least the first electric heater is energized, and after the internal combustion engine is started, either the first electric heater or the second electric heater is energized depending on the warm-up state of the internal combustion engine. This is achieved by means of an internal combustion engine intake air heating device which is configured such that only the internal combustion engine is selectively energized.

<Operations and Effects of the Invention> According to the above-described configuration, the first electric heater with a large heat generating capacity is always activated to heat the intake air before starting the engine, so-called intake air preheating, in order to shorten the start waiting time. On the other hand, for intake air heating after the engine is started, use of the first electric heater and the second electric heater is selected depending on the warm-up state of the internal combustion engine. As a result, intake air preheating for improving startability is performed quickly, and intake air heating after engine startup is performed in just the right amount depending on the warm-up state.

<Embodiments> The present invention will be described in detail below with reference to embodiments with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing one embodiment of a diesel engine equipped with an intake air heating device according to the present invention in an intake system. In Fig. 1, numeral 1 indicates a diesel engine, and although not shown in the figure, the diesel engine has a plurality of cylinders, that is, combustion chambers, each of which is controlled by an intake valve. Air is taken in through an intake port that is opened and closed, and liquid fuel is injected and supplied through a fuel injection nozzle (not shown).

An intake manifold 2 is attached to one side of the diesel engine 1. Intake manifold 2
has one collecting pipe part 4 and a plurality of branch pipe parts 3 of the same number as the number of cylinders of the diesel engine 1, and each of the branch pipe parts 3 communicates with each intake port of the diesel engine 1. There is.

One intake pipe 5 is connected to the collecting pipe part 4 of the intake manifold 2, and an intake control valve 6 is provided near the connecting end of the intake pipe to the collecting pipe part 4. The intake control valve 6 is supported from the intake pipe 5 by a valve shaft 7, is drivingly connected to an accelerator system (not shown), and opens in response to depression of an accelerator pedal.

In this embodiment, the intake control valve 6 is provided with a notch 8, which allows the diesel engine 1 to take in a relatively small predetermined flow rate of air even when the intake control valve 6 is in its fully closed position. It is becoming possible to do so.

Each branch pipe portion 3 of the intake manifold 2 is provided with a first electric heater 9 and a second electric heater 10 for heating intake air. These electric heaters are composed of semiconductor heaters such as PTC heaters, ceramic heaters, nichrome wire heaters, etc., and are selectively supplied with current from a battery power source 11 via relay switches 12a and 12b. A first electric heater 9 and a second electric heater 10 are provided in each branch pipe section 3, and the first electric heater 9 has a relatively large first heat generation capacity, and the second electric heater 9 has a relatively large first heat generation capacity. The electric heater has a second heat generation capacity smaller than the first heat generation capacity. That is, the second electric heater 10 is smaller than the first electric heater 9.

Opening/closing control of relay switches 12a and 12b is performed by a control device 13. The control device 13 is
An engine key switch 14 that detects that the engine key is inserted into the keyhole, and a water temperature sensor 15 that detects the temperature of the cooling water of the diesel engine 1.
Then, a signal is input from the starter switch 16 which detects that the starter is activated, and when the engine key switch 14 detects that the engine key is inserted into the keyhole, the water temperature sensor 15 is activated.
The engine cooling water temperature Tw detected by
If it is less than Ta, close the relay switch 12a,
From this, the time determined according to the cooling water temperature
After t ₁ has elapsed, open the relay switch 12a,
Also, it is determined whether or not the starting of the diesel engine 1 is completed based on a signal from the starter switch 16, and when the engine starting is completed, the engine cooling water temperature Tw detected by the water temperature sensor 15 is set to a predetermined value lower than the predetermined value Ta. Determine whether it is below Tb,
When Tw<Tb, the relay switch 12a is closed, whereas when Tw<Tb is not the case, the relay switch 12b is closed, and after a time t ₂ seconds determined according to the cooling water temperature has elapsed, the relay switch 12a is closed. Or it is designed to open 12b. Relay switch 12a or 12
b, in other words, the energization times t ₁ and t ₂ for the first or second electric heaters 9, 10 are determined by the cooling water temperature, as shown in FIGS. 2 and 3, respectively. The lower the value, the longer the time is set.

As described above, by controlling the energization to the electric heaters 9 and 10, during a cold start when heating the intake air is required, the first electric heater 9, which has a relatively large heat generation capacity, is energized. This generates heat and the intake air is heated rapidly, and the intake air heating time is set longer as the temperature is lower depending on the engine temperature, improving startability no matter what temperature the engine is in. Intake air heating is performed appropriately.

After the engine starts, depending on the cooling water temperature at that time,
That is, in accordance with the warm-up state of the diesel engine 1, when the engine cooling water temperature Tw is extremely cold and is lower than the predetermined value Tb, the first electric heater 9 having a large heat generating capacity is energized; is the predetermined value Tb
The second electric heater 10 has a smaller heat generation capacity than the first electric heater 9 during the above normal cold state.
energization is performed. As a result, appropriate intake air heating is performed according to the engine temperature, and the intake air heating time is set to be longer as the temperature is lower depending on the engine temperature state, so that no matter what the engine temperature is, white smoke will not occur. As a countermeasure, intake air heating is carried out appropriately to the minimum necessary level.

FIG. 4 is a flow chart showing an example of a control procedure for the intake air heating device according to the present invention described above.

In the illustrated embodiment, an indicator lamp 17 is provided to indicate that the electric heater 9 is energized before starting the engine. The energization is controlled by the heater 9, and the light is turned on only when the electric heater 9 is energized for preheating the intake air. Therefore, the diesel engine 1 may be started by the starter after waiting for the indicator lamp 17 to go out.

Note that the starter may be configured not to operate even if the starter switch is operated while the electric heater 9 is energized for preheating the intake air.

FIG. 5 is a flowchart showing another example of the control procedure for the intake air heating device according to the present invention. In this flowchart, intake air heating to prevent white smoke after engine startup is performed until the cooling water temperature reaches a predetermined value Tc or higher. This predetermined value Tc may be set to a cooling water temperature at which the diesel engine 1 does not substantially emit white smoke.

FIG. 6 shows another embodiment of the intake air heating device according to the present invention. In such embodiments,
An intake air heater 18 having a built-in first electric heater 19 having a relatively large heat generation capacity and another electric heater 20 having a smaller heat generation capacity than the electric heater 19 is connected to the collecting pipe portion of the intake manifold 2. An intake pipe 5 having an intake control valve 6 is connected to the intake air heater.

The electric heaters 19 and 20 are connected to the relay switch 1 from the battery power source 11 as in the above embodiment.
2a and 12b, and the opening and closing of the relay switch is controlled by a control device 13 which operates in the same manner as in the embodiment described above.

Therefore, in the embodiment shown in FIG.
It will be understood that effects similar to those shown in the figures can be obtained.

In the above, the present invention has been described in detail with respect to specific embodiments, but the present invention is not limited to these, and it is understood that various embodiments are possible within the scope of the present invention. It will be clear to those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of a diesel engine equipped with an intake air heating device according to the present invention in the intake system, and FIGS. 2 and 3 are diagrams showing an electric heater in the intake air heating device according to the present invention. Graphs showing current application time characteristics with respect to cooling water temperature, FIGS. 4 and 5 are flowcharts showing examples of control procedures for the intake air heating device according to the present invention, and FIG. 6 is a flow chart showing another example of the intake air heating device according to the present invention. FIG. 2 is a schematic configuration diagram showing two embodiments. DESCRIPTION OF SYMBOLS 1... Diesel engine, 2... Intake manifold, 3... Branch pipe section, 4... Collecting pipe section, 5... Intake pipe, 6... Intake control valve, 7... Valve shaft, 8... Notch part , 9...first electric heater, 10...second electric heater, 11...battery power supply, 12a,
12b...Relay switch, 13...Control device,
14...Engine key switch, 15...Water temperature sensor, 16...Starter switch, 17...Indicator lamp, 18...Intake air heater, 19,2
0...Electric heater.

Claims (1)

[Scope of utility model registration request] A first electric heater provided in the middle of the intake passage and having a first heat generation capacity; and a second electric heater provided in the middle of the intake passage and having a second heat generation capacity smaller than the first heat generation capacity. and a control means for controlling energization to the first and second electric heaters, wherein at least the first electric heater is energized before starting the internal combustion engine and after starting the internal combustion engine. An intake air heating device for an internal combustion engine, wherein only one of the first electric heater and the second electric heater is selectively energized depending on a warm-up state of the internal combustion engine.