JP2000257518A - Air heater for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air heater for internal combustion engine capable of obtaining optimum heating characteristics corresponding to preheating and afterheating to prevent excessive rise of temperature and reducing power consumption and cost. SOLUTION: This air heater for an internal combustion engine is provided with an air heater in the upstream 5a arranged on an external air side UP in an air intake passage IP of the internal combustion engine and an air heater in the downstream 5b arranged on the internal combustion engine side LP in the air intake passage IP. Both of the air heaters 5a, 5b are constituted by connecting PTC elements 6 in series for heater elements 7 consisting of heating type heat generation bodies. The PTC element 6 of the air heater on the downstream 5b is heated by heat transfer from the air heater in the upstream 5a. The heat transfer is done through constituent members of each air heater 5a, 5b and by directly blowing the intake air heated by the heater element 7 of the air heater in the upstream 5a on the PTC element 6 of the air heater in the downstream 5b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air heater for an internal combustion engine, and more particularly, to an air heater for an internal combustion engine used for heating intake air for heating the intake air of the internal combustion engine to facilitate starting.

[0002]

2. Description of the Related Art Generally, it is difficult to start an internal combustion engine when the outside air temperature is low such as in winter. In particular, in a self-ignition type internal combustion engine such as a diesel engine, when the temperature of the intake air is low, the air compressed in the cylinder does not reach the ignition state and combustion may not easily occur. In view of the above, an intake air heating device (combustion assist device) has been conventionally provided in which an intake air heater having an electrothermal heating element is disposed in an intake passage to preheat intake air so as to smoothly start an internal combustion engine. Various proposals have been made.

The present applicant has also proposed an air heater for an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 9-245939 as an air heater used for an intake air heating device. this is,
PTC in series with the heater element consisting of an electric heating element
The elements are connected, and the PTC element is heated by heat transfer from the heater element.

Here, the PTC element is a heat-sensitive resistance element having a positive temperature resistance coefficient such that the resistance value increases when a certain temperature is reached. Therefore, in the air heater for an internal combustion engine described in the same publication, when energization is started and the temperature of the heater element rises, the PTC element is heated not only by self-heating of the PTC element but also by heat transfer from the heater element. Therefore, the temperature of the PTC element rapidly rises and its resistance value increases. Therefore, the current flowing through the heater element is limited, and the excessive rise in temperature of the heater element is suppressed.

That is, the air heater for an internal combustion engine described in the above publication does not use a PTC element as a main heating element, but uses a heater element as a main heating element. In comparison, the temperature of the whole air heater can be increased to improve the heating efficiency. In addition, since the PTC element is used as a control element for preventing overheating of the heater element, there is no need to provide a special control device for preventing overheating of the heater element, and the overall configuration of the air heater is simplified. Can be

[0006]

The air heater for an internal combustion engine described in the above publication is interposed in an intake passage communicating an air cleaner and an intake manifold of the internal combustion engine, and heats intake air flowing through the intake passage.

At the time of starting the internal combustion engine, it is general practice to energize the air heater for the internal combustion engine for a certain time before cranking, which is called preheating. If the air heater for an internal combustion engine described in the above-mentioned publication is used, if preheating is performed for a long time (for example, a driver's erroneous operation, a failure of a control device, welding of a current-carrying relay contact, etc.) occur as described above. And PTC
PTC starts when the temperature of the device rises and exceeds a certain temperature.
The resistance value of the element increases, the current flowing through the heater element is limited, and the excessive heating of the heater element is suppressed.

However, once the resistance value of the PTC element increases, the voltage applied to the PTC element increases,
Since the C element tends to generate heat at a constant power, the PTC element maintains its constant temperature heating state due to its own heat generation. Therefore, even if the cooling is forcibly performed, the resistance value of the PTC element is considerably reduced to its original value. It takes time. Therefore, the amount of intake air flowing through the intake passage increases, the heater element is cooled, and even after the temperature of the heater element decreases, the current flowing through the heater element is limited by the PTC element. It takes time to complete.

Therefore, when cranking is started after the preheating is performed for a long time, the current flowing through the heater element is limited by the self-heating of the PTC element, so that the temperature of the heater element hardly rises, and the intake air is exhausted. It will not be heated enough.

Accordingly, in the air heater for an internal combustion engine described in the above publication, when cranking is performed after preheating, energization to the air heater for an internal combustion engine is prohibited for a predetermined period. With this configuration, the PTC element does not self-heat during the predetermined period during which the energization is prohibited, and the PTC element is cooled by the intake air during the predetermined period to reduce the resistance value. Is not limited, and the time until the heater element is reheated can be shortened.

Incidentally, the intake air heating after the preheating by the air heater for the internal combustion engine is called after-heating. There are two types of after-heat: intake air heating during idling of the internal combustion engine and intake air heating during operation.When idling, intake air heating is suppressed to reduce the load on the onboard battery, and during operation, the rotational speed of the internal combustion engine increases. It is necessary to increase the intake air heating corresponding to the increase in the intake air amount.

As described above, in the air heater for an internal combustion engine described in the above publication, unless the control of prohibiting the energization of the air heater for the internal combustion engine for a predetermined period is performed, the intake air amount increases during the operation of the internal combustion engine. In addition, it is not possible to obtain a heating characteristic that quickly responds to the increase in the intake air amount. But,
In this case, it is necessary to provide a special control device for prohibiting energization of the air heater for the internal combustion engine for a predetermined period,
There is a problem that the cost increases because the configuration of the entire air heater is complicated.

In view of this, it is conceivable to use a PTC element used in the air heater for an internal combustion engine described in the above-mentioned publication which has a small minimum resistance value (Rmin) and a small increase in resistance value with respect to temperature rise. With this configuration, the current limitation of the heater element due to the self-heating of the PTC element can be suppressed without performing the control of prohibiting the energization of the air heater for the internal combustion engine for a predetermined period. Heating characteristics that quickly respond to an increase in the amount can be obtained. However, in this case, even at the time of idling, the current flowing through the PTC element and the heater element increases, and thus there is a problem that power consumption at the time of idling increases.

In the air heater for an internal combustion engine described in the above publication, the power consumption of the air heater for the internal combustion engine is controlled by switching according to the operating state of the internal combustion engine (preheating, idling, operating). Can be considered. That is, the power consumption of the air heater for the internal combustion engine is controlled so as to be large during preheating, small during idling, and large according to the intake air amount during operation. In this way, it is possible to improve the startability of the internal combustion engine by increasing the intake air heating at the time of preheating, to reduce the power consumption at the time of idling, and to have a heating characteristic that quickly responds to an increase in the amount of intake air at the time of operation. Can be realized. However, in this case, it is necessary to provide a special control device for switching and controlling the power consumption of the air heater for the internal combustion engine according to the operation state of the internal combustion engine, and the overall configuration of the air heater becomes complicated, resulting in an increase in cost. There is a problem of doing.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain optimum heating characteristics corresponding to preheating and afterheating, and to prevent excessive heating. An object of the present invention is to provide an air heater for an internal combustion engine that can reduce power consumption and cost.

[0016]

Means for Solving the Problems and Effects of the Invention The invention according to the first aspect of the present invention, which has been made to achieve the above object, comprises an upstream air heater disposed on the outside air side in an intake passage of an internal combustion engine; A downstream air heater disposed on the side of the internal combustion engine in the intake passage, wherein the upstream and downstream air heaters are both configured by connecting a PTC element in series to a heater element formed of an electrothermal heating element, The gist is an air heater for an internal combustion engine in which a PTC element of the downstream air heater is heated by heat transfer from the side air heater.

Therefore, in the present invention, the PTC element is not used as the main heating element, and the heater element is used as the main heating element. The heating efficiency can be improved by increasing the temperature of the entire air heater.

At the time of preheating of the internal combustion engine, P
Since the TC element is used as a control element for preventing the heater element from overheating, there is no need to provide a special control device for preventing the heater element from overheating.
The overall configuration of the air heater for the internal combustion engine can be simplified.

Next, when the internal combustion engine is idling, both air heaters are cooled by the intake air, so that the temperatures of both air heaters decrease. At this time, since the PTC element of the downstream air heater is heated by the heat transfer from the heater element of the upstream air heater, the temperature of the downstream air heater is higher than the temperature of the upstream air heater. If this state continues for a certain period of time, the temperature of the PTC element of the downstream air heater rapidly rises, the resistance value of the PTC element of the downstream air heater increases, and the current flowing through the heater element of the downstream air heater is limited and reduced. Therefore, the sum of the currents flowing through both heaters sharply decreases, and the sum of the power consumption of each air heater also decreases. As a result, the temperature of the downstream air heater also sharply decreases. On the other hand, the current flowing to the upstream air heater does not change, and the temperature of the upstream air heater does not change.

Subsequently, during operation of the internal combustion engine, the upstream air heater is greatly cooled by the increased intake air, so that the temperature of the upstream air heater decreases. Then, since the temperature of the intake air heated by the heater element of the upstream air heater also decreases, the temperature of the PTC element of the downstream air heater also decreases as the temperature of the intake air decreases. Therefore, the resistance value of the PTC element of the downstream air heater decreases, and the restriction on the current flowing through the heater element of the downstream air heater is released. , The total power consumption increases. As a result, the temperature of the downstream air heater also increases, and the temperature of the downstream air heater becomes higher than the temperature of the upstream air heater.

Therefore, at the time of preheating, it is possible to improve the startability of the internal combustion engine by increasing the power consumption while preventing the overheating of the heater element. In addition, power consumption during idling can be reduced. And
During operation, excellent heating characteristics can be obtained by increasing power consumption in response to an increase in the amount of intake air quickly. In addition, there is no need to provide a special control device when optimizing the power consumption of each air heater according to the operating state of the internal combustion engine (during preheating, idling, and operation). However, the cost of the entire air heater for an internal combustion engine can be reduced without complicating the structure.

The operating state of the internal combustion engine (at the time of preheating,
In order to optimize the power consumption of each air heater according to the idling time and the operation time, the resistance values of the PTC element and the heater element in each air heater may be appropriately set. Next, according to a second aspect of the present invention, in the air heater for an internal combustion engine according to the first aspect, the intake air heated by the heater element of the upstream air heater directly hits the PTC element of the downstream air heater. The gist is that it is configured as

Therefore, according to the present invention, since the intake air heated by the heater element of the upstream air heater directly hits the PTC element of the downstream air heater, the heat of the upstream air heater transfers the PTC element of the downstream air heater. The PTC element is efficiently heated, and the effects of the invention described in claim 1 can be more reliably obtained.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. In each embodiment,
The same components have the same reference numerals, and a detailed description thereof will be omitted.

(First Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the first
FIG. 1 is a configuration diagram illustrating a configuration of an air heater system 1 for an internal combustion engine according to an embodiment.

The air heater system 1 for an internal combustion engine includes a vehicle-mounted battery 2, an electromagnetic relay 3, a controller 4, and air heaters 5a and 5b for heating intake air. The air heaters 5a and 5b having the same configuration are stacked and integrated, and are interposed in an intake passage IP that communicates an air cleaner with an intake manifold of an internal combustion engine.
The intake air flowing through the heater is heated. Here, the air heater 5a is disposed on an air cleaner side (hereinafter, referred to as an upstream side) UP on the outside air side of the intake passage IP, and the air heater 5b is disposed on an intake manifold side (hereinafter, referred to as downstream side) on the internal combustion engine side of the intake passage IP. ) LP.

Each of the air heaters 5a and 5b has a PTC element 6
And a heater element 7 composed of an electric heating element are electrically connected in series. The air heaters 5a and 5b are electrically connected in parallel. The heater element 7 of the air heater 5a and the PTC element 6 of the air heater 5b are arranged in series in the direction of the intake passage IP. Therefore, as shown by the arrow A, the upstream side U
The intake air heated by the heater element 7 of the air heater (hereinafter, referred to as an upstream air heater) 5a disposed on the P is supplied to the PTC element 6 of the air heater (hereinafter, referred to as the downstream air heater) 5b disposed on the downstream LP. Is to hit directly.

Between the plus and minus terminals of the vehicle-mounted battery 2, the air heaters 5a and 5b connected in parallel with the electromagnetic relay 3 are connected in series. ON / OFF of the electromagnetic relay 3 is controlled by the controller 4. In order to smoothly start the internal combustion engine, it is necessary to increase the amount of heat generated by each of the air heaters 5a and 5b.
The power consumption of a and 5b must be increased. However, when the resistance value of the heater element 7 is reduced, the durability of the heater element 7 tends to decrease because the temperature of the heater element 7 rises rapidly during preheating. Therefore, the controller 4 controls the on / off of the electromagnetic relay 3 to control the energization of each of the air heaters 5a and 5b so that the temperature of the heater element 7 does not exceed a predetermined temperature (for example, 900 ° C.). The control method of the air heaters 5a and 5b using the electromagnetic relay 3 is described in detail in the third embodiment of the above-mentioned publication (Japanese Patent Application Laid-Open No. 9-245939), and the description is omitted here.

FIG. 2A is a plan view of the air heaters 5a and 5b, and FIG. 2B is a front view showing a state in which the air heaters 5a and 5b are stacked and integrated. Air heater 5
Each of a and 5b includes a rectangular outer frame 11 formed by aluminum alloy die-casting, and a partition 12 extending inside the outer frame 11. Two rectangular holes 13a and 13b surrounded by the outer frame 11 and the partition 12 are communicated with the intake passage IP to form a part thereof. Outer frame 1
Holes 11a are formed in the four corners of the air heater 1, and the air heaters 5a and 5b are integrally laminated and connected to an air cleaner or an intake manifold by bolts (not shown) inserted into the holes 11a. Attached to an internal combustion engine.

The heater element 7 is arranged in the hole 13a, and the PTC element 6 is arranged in the hole 13b.
The air heater 5b is mounted at a position rotated by 180 ° with respect to the air heater 5a. Therefore, as described above, the heater element 7 of the upstream air heater 5a and the PTC element 6 of the downstream air heater 5b are arranged in series in the passage direction of the intake passage IP.

The PTC element 6 is formed of a plate-like material having a thickness of about 1 mm and made of a ceramic sintered body having an appropriate composition (for example, a barium titanate (BaTiO ₃ ) -based sintered body). On both sides of the PTC element 6, a suitable metal having a small electric resistance (for example, brass, copper, aluminum, etc.)
Is formed. Holding electrode 14
The radiating fins 15 are arranged outside the fin. The radiation fin 15 is made of an appropriate metal having a small specific heat (for example, brass,
(Aluminum, copper, aluminum, etc.), and the thin strip has a meandering shape that is continuously curved, so the contact area with the intake air is large and the flow direction of the intake air is large. Has a smaller projected area.

The curved portion of the thin strip forming the radiation fins 15 is embedded in an insulator 16b made of an appropriate insulating material (for example, various ceramics such as alumina, zirconia, steatite, etc.). The insulator 16b is fitted in the metal bracket 18b. If the insulator 16b is formed of a resin material such as PPS, the metal bracket 18b can be omitted.

The heater element 7 is made of an electric heating element made of a suitable material (for example, iron-chromium alloy, stainless steel, etc.).
Is formed by a thin plate-like band composed of: The thin plate-like band has a meandering shape that is continuously curved, so that the contact area with the intake air is large, and the projected area in the flow direction of the intake air is small. Has become. A heater element having such a configuration is generally called a ribbon heater.

The curved portion of the thin strip forming the heater element 7 is embedded in the insulator 16a. The insulator 16a is fitted into the metal bracket 18a via the wave spring 17. Therefore, the heater element 7 is urged in the center direction by the wave spring 17, and the vibration generated during the operation of the internal combustion engine is suppressed.

On both sides of the outer frame 11, both terminals 19a and 19b of the PTC element 6 and both terminals 20a of the heater element 7 are provided.
a and 20b are respectively provided through the insulating plate 21. Each terminal 19a, 19b is connected to the holding electrode 14 respectively.
, And the terminals 20 a and 20 b are connected to a thin strip forming the heater element 7.

When the terminals 19a and 20a are electrically connected by the short plate 22,
The TC element 6 and the heater element 7 are electrically connected in series. A cover 23 is attached to each terminal 19a, 20a. Also, the terminal 19 of the upstream air heater 5a
b and the terminal 20b of the downstream air heater 5b are connected to the plus terminal side of the vehicle-mounted battery 2, and the terminal 20b of the upstream air heater 5a and the terminal 19b of the downstream air heater 5b are connected.
b is connected to the minus terminal side of the vehicle-mounted battery 2 so that the air heaters 5a and 5b are electrically connected in parallel.

Next, the operation and effect of the air heater system 1 for an internal combustion engine configured as described above will be described.
FIG. 3 is a characteristic diagram showing the results of an experiment performed to confirm the operation and effect of the air heater system 1 for an internal combustion engine.

The horizontal axis of FIG. 3 shows the time elapsed since the electromagnetic relay 3 was turned on by the controller 4. Then, air is blown into the intake passage IP using an experimental blower, and the temperatures of the air heaters 5a and 5b and the on-board battery 2
And the sum of the currents supplied to the air heaters 5a and 5b (hereinafter referred to as the total heater current).

Here, from the time when the electromagnetic relay 3 is turned on (time T0) to the time T1 (after 30 seconds), air is not blown into the intake passage IP, and the time from the time T1 to the time T2 (time T
From 0 to about 570 seconds), the air flow rate is 1000 L / min
After time T2, the air flow rate was set to 2000 L / min.

That is, the period from time T0 to T1 corresponds to the preheating state of the internal combustion engine, and from time T1 corresponds to the afterheating state of the internal combustion engine.
The period 2 corresponds to the idling state of the internal combustion engine, and the period after time T2 corresponds to the operation state of the internal combustion engine.

In the preheat state between times T0 and T1, the temperature rises of the air heaters 5a and 5b are the same, and the same operation and effect as those of the air heater for an internal combustion engine described in the above-mentioned publication (Japanese Patent Application Laid-Open No. 9-245939) are obtained. Can be That is, in each of the air heaters 5a and 5b, when the temperature of the heater element 7 rises, not only the self-heating of the PTC element 6 but also the members (11, 12, 14) from the heater element 7 are generated.
Since the PTC element 6 is heated by the heat transfer via １８18b), the temperature of the PTC element 6 rises rapidly and the resistance value increases. Therefore, the current flowing through the heater element 7 is limited, and excessive heating of the heater element 7 is suppressed. That is, since the PTC element 6 is not used as the main heating element and the heater element 7 is used as the main heating element, the temperature of the entire air heaters 5a and 5b is lower than when only the PTC element 6 is used as the heating element. And the heating efficiency can be improved. In addition, PT
Since the C element 6 is used as a control element for preventing the overheating of the heater element 7, it is not necessary to provide a special control device for preventing the overheating of the heater element 7, and each of the air heaters 5a and 5b is provided separately. Can be simplified.

Then, at time T1, when the air conditioner shifts to the idling state and the amount of air blows becomes 1000 L / min, the air heaters 5a and 5b are cooled by the air blow (intake air), so that the temperatures of the air heaters 5a and 5b become lower. Go down. At this time, the intake air heated by the heater element 7 of the upstream air heater 5a directly hits the PTC element 6 of the downstream air heater 5b. In addition, from the PTC element 6 and the heater element 7 of the upstream air heater 5a, each member (11, 12, 14 to 1) of each air heater 5a, 5b is obtained.
The downstream air heater 5b is heated by the heat transfer via 8b). Therefore, the temperature of the downstream air heater 5b is higher than the temperature of the upstream air heater 5a.

The state in which the intake air heated by the heater element 7 of the upstream air heater 5a directly hits the PTC element 6 of the downstream air heater 5b continues. in addition,
From the PTC element 6 and the heater element 7 of the upstream air heater 5a, each member (1
The state in which the PTC element 6 of the downstream air heater 5b is heated by the heat transfer via (1, 12, 14 to 18b) continues.

Therefore, the time Ta (about 30 minutes after the time T0)
(After 0 seconds), the temperature of the PTC element 6 of the downstream air heater 5b rapidly rises. Accordingly, the resistance value of the PTC element 6 of the downstream air heater 5b increases, and the current flowing through the heater element 7 of the downstream air heater 5b is limited and reduced, so that the total heater current sharply decreases. As a result, the temperature of the downstream air heater 5b also sharply decreases. On the other hand, the current flowing to the upstream air heater 5a does not change, and the temperature of the upstream air heater 5a does not change.

After that, at time T2, when the operation state is shifted to the air blowing amount of 2000 L / min, the upstream air heater 5a is greatly cooled by the increased air blowing (intake air), so that the temperature of the upstream air heater 5a is reduced. Goes down. Then, since the temperature of the intake air heated by the heater element 7 of the upstream air heater 5a also decreases, the PTC of the downstream air heater 5b decreases with the decrease in the temperature of the intake air.
The temperature of the element 6 also decreases. For this reason, the resistance value of the PTC element 6 of the downstream air heater 5b decreases, and the restriction on the current flowing through the heater element 7 of the downstream air heater 5b is released to increase, so that the total heater current sharply increases. As a result, the temperature of the downstream air heater 5b also increases, and the temperature of the downstream air heater 5b becomes higher than the temperature of the upstream air heater 5a as in the period from time T1 to time Ta.

As described in detail above, according to the air heater system 1 for an internal combustion engine of the first embodiment, at the time of preheating, the same air heater system as the air heater for an internal combustion engine described in the above-mentioned publication (JP-A-9-245939) is used. Functions and effects can be obtained. Further, at the time of idling, the current flowing through the downstream air heater 5b is limited and reduced, and the total heater current is reduced accordingly.
The total power consumption of b can be reduced. At the time of operation, the restriction on the current flowing through the downstream air heater 5b is released and increased, and the total heater current increases accordingly. Therefore, the total power consumption of the air heaters 5a and 5b can be increased.

Therefore, at the time of preheating, it is possible to improve the startability of the internal combustion engine by increasing the power consumption while preventing the overheating of the heater element 7. In addition, power consumption during idling can be reduced. During operation, excellent heating characteristics can be obtained by increasing power consumption in response to an increase in the amount of intake air. In addition, when optimizing the power consumption of each of the air heaters 5a and 5b according to the operating state of the internal combustion engine (preheating, idling, and operation), it is not necessary to provide a special control device. 5a,
5b does not become complicated, and the cost of the air heater system 1 for the internal combustion engine can be reduced.

Here, each air heater 5 depends on the operation state of the internal combustion engine (preheating, idling, operation).
To optimize the power consumption of each air heater 5a and 5b,
The resistance values of the PTC element 6 and the heater element 7 in a and 5b may be appropriately set.

However, due to the heat generated by the PTC element 6 itself, P
In a state where the temperature of the TC element 6 rises, an error occurs in the operation of limiting the current of the heater element 7 depending on the temperature of the heater element 7, and therefore, the setting method of the resistance values of the PTC element 6 and the heater element 7 is as follows. It is necessary to employ the method described in detail in Example 1 of the above publication (JP-A-9-245939).

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to the drawings. FIG.
FIG. 1 is a configuration diagram illustrating a configuration of an air heater system 31 for an internal combustion engine according to an embodiment.

The air heater system 31 for the internal combustion engine differs from the air heater system 1 for the internal combustion engine of the first embodiment in that the heater element 7 of the upstream air heater 5a and the PTC element 6 of the downstream air heater 5b are connected to the intake passage IP. It is not arranged in series, and the upstream air heater 5a
PTC element 6 of downstream air heater 5b and PTC element 6 of downstream air heater 5b
Are arranged in series in the intake passage IP.

Therefore, in the second embodiment, the intake air heated by the heater element 7 of the upstream air heater 5a does not directly hit the PTC element 6 of the downstream air heater 5b. However, the intake air heated by the PTC element 6 of the upstream air heater 5a is
In addition to directly hitting the C element 6, the suction air heated by the heater element 7 of the upstream air heater 5a also slightly hits the PTC element 6 of the downstream air heater 5b. In addition, heat is transmitted from the PTC element 6 and the heater element 7 of the upstream air heater 5a via the members (11, 12, 14 to 18b) of the air heaters 5a and 5b.
The PTC element 6 of the downstream air heater 5b is still heated.

Therefore, also in the second embodiment, the first
Although it is slightly inferior to the embodiment, substantially the same operation and effect can be obtained. (Third Embodiment) Next, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 5 is a configuration diagram showing the configuration of the air heater system 41 for an internal combustion engine according to the third embodiment. The air heater system 41 for an internal combustion engine differs from the air heater system 1 for an internal combustion engine of the first embodiment in the following points.

(1) Each air heater 5a, 5b is a PTC
The heater element 6 is connected to both ends of the element 6 in series. (2) The heater element 7 of the upstream air heater 5a and the PTC element 6 of the downstream air heater 5b are not arranged in series in the intake passage IP.
The C element 6 and the PTC element 6 of the downstream air heater 5b are arranged in series in the intake passage IP.

FIG. 6A is a plan view of each of the air heaters 5a and 5b in the third embodiment. FIG. 6 (b)
It is a front view showing the state where each air heater 5a, 5b in this 3rd embodiment was laminated and integrated. As described above, according to the third embodiment, in addition to obtaining the same operation and effect as the second embodiment, the heater elements 6 are connected in series to both ends of the PTC element 6, and the air heaters 5a, 5a, 5
Since b is configured, each air heater 5a, 5b can be made compact and the heating efficiency can be increased.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to the drawings. FIG.
FIG. 1 is a configuration diagram illustrating a configuration of an air heater system 51 for an internal combustion engine according to an embodiment.

The air heater system 51 for an internal combustion engine differs from the air heater system 1 for an internal combustion engine of the first embodiment in that the PTC element 6 and the heater element 7 in each of the air heaters 5a and 5b are connected in series in the direction of the intake passage IP. It is located at the point.

FIG. 8A is a plan view of each of the air heaters 5a and 5b in the fourth embodiment. FIG. 8 (b)
It is a bottom view of each air heater 5a, 5b in the fourth embodiment. FIG. 8C is a front view of each of the air heaters 5a and 5b in the fourth embodiment.

In each of the air heaters 5a and 5b, a PTC
The element 6 and the heater element 7 are stacked. Therefore, in the fourth embodiment, the cross-sectional area of the intake passage IP can be reduced as compared with the case where the PTC element 6 and the heater element 7 are arranged on a plane as in the first to third embodiments. .

As described above, in the fourth embodiment, as shown by the arrow B in FIG. 7, in each of the air heaters 5a and 5b, the intake air heated by the PTC element 6 directly hits the heater element 7. ing. Further, as shown by an arrow A in FIG. 7, the intake air heated by the heater element 7 of the upstream air heater 5a is supplied to the downstream air heater 5a.
b directly hits the PTC element 6. Therefore, according to the fourth embodiment, in addition to obtaining the same operation and effect as the first embodiment, the cross-sectional area of the intake passage IP is reduced, so that the entire air heaters 5a and 5b can be made compact. Can be.

FIG. 9 is a configuration diagram showing a configuration of an air heater system 61 for an internal combustion engine which is a modification of the fourth embodiment. The air heater system 61 for an internal combustion engine differs from the air heater system 51 for an internal combustion engine in that the connection between the PTC element 6 and the heater element 7 of the downstream air heater 5b is reversed. That is, in the fourth embodiment, in each of the air heaters 5a and 5b, even if the connection between the PTC element 6 and the heater element 7 is reversed, the operation and operation are not performed.
There is little difference in effect. Accordingly, in each of the air heater systems 51 and 61 for the internal combustion engine, each air heater 5
The connection between the PTC elements 6a and 5b and the heater element 7 may be reversed.

The present invention is not limited to the above embodiments, but may be modified as follows.
The effect can be obtained. (1) Instead of assembling and laminating and integrating the air heaters 5a and 5b having the same configuration, the outer frame 11 of each of the air heaters 5a and 5b is integrated into
a and 5b may be formed as an integral object from the beginning.

(2) In each of the air heaters 5a and 5b,
The positional relationship between the PTC element 6 and the heater element 7 is determined by the shape of the intake passage IP, the flow rate of the intake air, and the thermal characteristics of the insulators, electrodes, and the like. Alternatively, changes may be appropriately made.

(3) The direction of the current in each of the above embodiments is not limited, and the direction of the current flowing through each air heater 5a, 5b can be changed by reversing the plus / minus connection of the vehicle-mounted battery 2. It may be reversed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram for explaining a configuration of a first embodiment that embodies the present invention.

FIG. 2A is a plan view of an air heater for an internal combustion engine according to the first embodiment. FIG. 2B is a front view of the air heater for the internal combustion engine of the first embodiment.

FIG. 3 is a characteristic diagram for explaining the operation and effect of each embodiment embodying the present invention.

FIG. 4 is a configuration diagram for explaining a configuration of a second embodiment that embodies the present invention.

FIG. 5 is a configuration diagram for explaining a configuration of a third embodiment that embodies the present invention.

FIG. 6A is a plan view of an air heater for an internal combustion engine according to a third embodiment. FIG. 6B is a front view of an air heater for an internal combustion engine according to the third embodiment.

FIG. 7 is a configuration diagram for explaining a configuration of a fourth embodiment that embodies the present invention.

FIG. 8A is a plan view of an air heater for an internal combustion engine according to a fourth embodiment. FIG. 8B is a bottom view of the air heater for an internal combustion engine according to the fourth embodiment. FIG. 8C is a front view of an air heater for an internal combustion engine according to a fourth embodiment.

FIG. 9 is a configuration diagram for explaining a configuration of a modification of the fourth embodiment.

[Explanation of symbols]

5a: Upstream air heater 5b: Downstream air heater
6 PTC element 7 Heater element IP Intake passage

Claims (2)

[Claims] An upstream air heater disposed on an outside air side in an intake passage of the internal combustion engine; and a downstream air heater disposed on the internal combustion engine side in the intake passage. In both cases, a PTC element is connected in series to a heater element composed of an electrothermal heating element, and the PTC element of the downstream air heater is heated by heat transfer from the upstream air heater. Air heater for an internal combustion engine. 2. The intake air heated by the heater element of the upstream air heater is supplied to the P
The air heater for an internal combustion engine according to claim 1, wherein the air heater is configured to directly hit the TC element.