JP2003072487A - Onboard power source control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an onboard power source control device capable of reduc ing the size and weight of the device constitution by omitting a heat radiating plate of a semiconductor relay. SOLUTION: In this onboard power source control device 1, when overheat of a relay unit RU is caused, the generation of overheat is detected on the basis of the total electric current quantity (or the total electric power quantity) supplied to a load L via a temperature sensor 5 or the relay unit RU, and power supply to the preset driving load L low in order of precedence is turned off or restrained to restrain a heating value of the relay unit RU.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted power supply control device having a plurality of semiconductor relays for distributing a vehicle-mounted power supply to respective loads.

[0002]

2. Description of the Related Art Conventionally, distribution of an on-vehicle power supply to each load has been performed by using a mechanical relay. However, due to recent advances in semiconductor technology, there is a movement to use a semiconductor relay using a semiconductor switching element (MOSFET or the like) instead of a mechanical relay.

In a semiconductor relay using a semiconductor switching element, heat is generated when an electric current flows due to the on resistance of the semiconductor switching element. Therefore, it is necessary to take measures against heat generation. Especially when a plurality of semiconductor relays are incorporated into one unit (relay unit),
The number of loads that were not originally supposed to be turned on at the same time (such a situation may occur when the Defogger switch is turned on continuously intentionally), and the relay unit overheats due to the heat generated by the semiconductor relay. Relay failure or shortened life, or IPS with overheat protection function
(Intelligent power switch) has a problem that the overheat protection function works and the power is temporarily turned off.

With respect to this point, in the conventional vehicle-mounted power supply control device, a large radiator plate is provided in the relay unit (or each semiconductor relay) to prevent the semiconductor relay from overheating.

[0005]

However, in the above-mentioned prior art, there is a problem that the large heat dissipation plate hinders reduction in size and weight of the vehicle-mounted power supply control device.

In view of the above problems, it is an object of the present invention to provide a vehicle-mounted power supply control device in which the heat dissipation plate of the semiconductor relay is omitted and the size and weight of the device can be reduced.

[0007]

[Means for Solving the Problems] A technical means for achieving the above-mentioned object is to provide a plurality of power supply paths for distributing power supplied from a power source to a plurality of loads and distributing the power to a plurality of loads. Having a semiconductor relay, each semiconductor relay controls the power supply state to each load, a relay unit, overheat detection means for detecting overheat of the relay unit, and controls each semiconductor relay to each load. While controlling the power supply state, when overheat is detected by the overheat detection means, power is supplied to at least a part of the loads that are being driven among the plurality of loads that are determined according to a predetermined condition. And a control means for turning off or suppressing.

Preferably, the overheat detecting means includes a temperature sensor for detecting the temperature of the relay unit, and a first overheat detecting section for detecting overheat of the relay unit based on the detection result of the temperature sensor. It is good to be prepared.

Also, preferably, the overheat detecting means is
A current detection unit that detects a current value supplied to the load via the relay unit, and a second overheat detection unit that detects overheating of the relay unit based on a detection result of the current detection unit. Is good.

Further, preferably, the overheat detecting means detects the operating state of each load based on the control signal of each load, and the above-mentioned operation based on the detection result of the operating state detecting section. A third overheat detection unit that estimates the amount of power supplied to each of the loads via the relay unit and detects overheating of the relay unit based on the amount of power may be provided.

Further, preferably, the overheat detecting means is
A temperature sensor that detects the temperature of the relay unit, a current detection unit that detects the current value supplied to the load via the relay unit, and the relay based on the detection results of the temperature sensor and the current detection unit And a fourth overheat detecting section for detecting overheating of the unit.

Further, preferably, the overheat detecting means includes a temperature sensor for detecting a temperature of the relay unit, and an operation state detecting section for detecting an operation state of each load based on a control signal of each load, Estimating the amount of power supplied to each load via the relay unit based on the detection result of the operating state detection unit, the relay unit of the relay unit based on the estimated power amount and the detection result of the temperature sensor A fifth overheat detection unit that detects overheat may be provided.

Further, preferably, the control means, when the overheat is detected by the overheat detecting means, at least a part of the plurality of loads during driving which is determined according to a predetermined condition. It is preferable that the power supply to the load is turned off after a lapse of a predetermined time from the occurrence of overheat.

[0014]

1 is a block diagram of an in-vehicle power supply control device according to an embodiment of the present invention. As shown in FIG. 1, the in-vehicle power supply control device 1 includes a relay unit RU in which a plurality of semiconductor relays R1 to R8 (reference numeral R is used when collectively referred to) are incorporated in one unit, a microcomputer 3, and a temperature. The sensor 5 is provided, and electric power supplied from a vehicle-mounted power source (not shown) such as a battery is supplied to the loads L1 to L8.
(The symbol L is used for the generic name) and is supplied.

The loads L1 to L4 are headlamps, the load L5 is a radiator fan, and the load L6.
Is a condenser fan, the load L7 is an audio device (or a navigation device), and the load L8 is a defogger.

Each semiconductor relay R of the relay unit RU
Is a branch power supply line (power supply path) 7a that is branched into a plurality of power supply lines 7 connected to the vehicle-mounted power supply and connected to each load L.
To control the supply state of the electric power supplied to each load L via the branch power supply line 7a.

In this embodiment, the semiconductor relay R is I
PS is used. This IPS includes a MOSFET 9 that functions as a switching element and the MOSFET 9
9 and a control circuit 11 for performing protection monitoring. The control circuit 11 drives the MOSFET 9 based on a signal given from the microcomputer 3, and
The protection of the FET 9 is monitored. The control circuit 11 includes a MOS
A current detection unit (not shown) that detects the current value of the current supplied to the load L via the FET 9 is provided, and the detection result of the current detection unit is given to the microcomputer 3.

The temperature sensor 5 detects the temperature of the relay unit RU and gives the detection result to the microcomputer 3.

The microcomputer 3 is provided with a control section (control means) 3a and an overheat detection section 3b as functional elements.
The overheat detecting unit 3b corresponds to the first to fifth overheat detecting units (particularly, the fourth overheat detecting unit) according to the present invention. The overheat detection unit 3b detects overheat of the relay unit RU based on the detection result of the temperature sensor 5 and the total amount of current (or the total amount of electric power) supplied to each load L via the relay unit RU. The total current amount (or total power amount) is calculated from the detection result of the current detection unit of the control circuit 11 of each semiconductor relay R.

As a more detailed specific example of this overheat detection, the following may be considered, for example. That is,
The first condition that the temperature detected by the temperature sensor 5 is equal to or higher than a reference temperature preset as an overheating reference, and the total current amount (or total electric energy) is equal to or higher than a reference value preset as an overheating reference. It is sequentially determined whether or not the second condition that the temperature is satisfied is satisfied, and it is determined that the overheating is performed when at least one of the first condition and the second condition is satisfied.

As a modification of this, the overheat may be detected only based on the detection result of the temperature sensor 5 or only based on the total current amount (or total power amount). In this case, for example, it is determined that overheating occurs when the first condition or the second condition is satisfied. In addition,
The temperature sensor 5 may be omitted when overheating is detected based only on the total amount of current (or the total amount of electric power).

The control unit 3a uses a signal line (eg LAN).
Based on an input signal for controlling the semiconductor relay R input via 13, the power supply state to each load L is controlled by controlling each semiconductor relay R (for example, ON, OFF control, or PWM control). Etc. adjust the amount of electric power supplied).

When the overheat detecting unit 3b detects overheating of the relay unit RU, the control unit 3a
The semiconductor relay R is controlled to turn off the power supply to at least a part of the loads L being driven, which is determined according to a predetermined condition (here, the priority order) among the plurality of loads L,
Alternatively, it is suppressed by PWM control.

Here, the load L is superior or inferior in importance from the viewpoint of maintaining the function of the vehicle. For example, headlamp L
1 to L4, the radiator fan L5, and the condenser fan L6 are necessary for the basic operation of the vehicle and are of high importance. On the other hand, the audio device (or navigation device) L7 and the defogger L8 are low in importance regardless of the basic operation of the vehicle.

Therefore, in this embodiment, priorities are set for a plurality of loads L according to their importance, and when overheat of the relay unit RU is detected, the priority (importance) of the loads L being driven is set. The power supply to the load L is turned off or suppressed in order from the low load L during driving. More specifically, when overheating of the relay unit RU is detected, the power supply to the audio device (or the navigation device) L7 and the defogger L8 is turned off or suppressed. In this way, when the load L (L7, L8 in this case) being driven at the time of overheat detection is turned off, the load L is not simply turned off along with the overheat detection, but a predetermined time (short time) after the overheat detection. Alternatively, the load L being driven may be driven and then turned off. by this,
For example, the power supply to the load L can be turned off after notifying the user when overheat is detected.

With such a configuration, the defogger L8, which is normally automatically turned off by a timer, is intentionally turned on continuously, and unexpected power is generated.
Is supplied to the load L via the relay unit RU and overheating of the relay unit RU occurs, the occurrence of overheat is detected based on the total current amount (or the total power amount) supplied to the temperature sensor 5 or the load L, The power supply to the load L (here, L7 and L8) during driving having a low priority set in advance is turned off or suppressed, and the heat generation amount of the relay unit RU is suppressed.

As a result, according to this embodiment, it is possible to prevent overheating of the relay unit RU without using a heat radiating plate as in the conventional case, and as a result, the semiconductor relay R
By omitting the heat radiating plate, the vehicle-mounted power supply control device 1 can be made smaller and lighter.

Further, since the relay unit RU is constructed so as to suppress the amount of heat generated by the relay unit RU and prevent overheating of the relay unit RU, the relay unit RU has higher reliability than the conventional overheat prevention method which relies on a heat sink. Can prevent overheating.

In the above embodiment, the total current amount (or total power amount) is calculated based on the detection result (measured value) of the current detecting portion of each semiconductor relay R, and is used for overheat detection. However, instead, an operation state detection unit that detects the operation state of each load L based on a control signal for controlling the operation state of each load L is provided as a functional element of the microcomputer 3, and the operation state detection unit is provided. Based on the detection result of (or based on the detection result of the current detection unit and the detection result of the operating state detection unit), the total current amount (or total electric energy) is estimated and used for overheat detection. Good. For example, the lamps L1 to L4 and the fans L5 and L6
For a load L having a function of adjusting the brightness, the number of revolutions, etc. as described above, by recognizing the operating state of the load L based on a control signal from an ECU that controls the load L,
The power consumption of the load L at that time can be estimated.

As a further modification of the above-described embodiment, an informing means (notifying output) to the in-vehicle power source control device 1 for informing output by at least one of light (including image display) and sound (including voice). Warning lights etc.),
When the relay unit RU is overheated (or when a predetermined load L is forcibly turned off or the supplied power is suppressed), the control unit 3 of the microcomputer 3
A warning may be given via the notification means by controlling a.

[0031]

According to the invention described in claims 1 to 7, when the overheat of the relay unit is detected by the overheat detecting means, the control means determines a predetermined one of the plurality of loads. The power supply to at least a part of the load during driving, which is determined according to the above conditions, is turned off or suppressed, which suppresses the heat generation amount of the relay unit. Can be prevented, and as a result, the heat dissipation plate of the semiconductor relay can be omitted, and the size and weight of the vehicle-mounted power supply control device can be reduced.

Further, since the configuration is such that the heat generation amount of the relay unit is suppressed and the relay unit is prevented from overheating, the overheating of the relay unit is more reliable than the conventional overheating prevention method which relies on a heat sink. Can be prevented.

According to the seventh aspect of the present invention, for example, the power supply to the load can be turned off after the user is notified when overheat is detected.

[Brief description of drawings]

FIG. 1 is a block diagram of an in-vehicle power supply control device according to an embodiment of the present invention.

[Explanation of symbols]

1 In-vehicle power supply control device 3 Microcomputer 5 Temperature sensor 7 power line 9 MOSFET 11 Control circuit L1 to L8 load R1 to R8 semiconductor relay RU relay unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shuji Mayama             1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi             Auto Network Technical Laboratory Co., Ltd. (72) Inventor Keizo Ikeda             1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi             Auto Network Technical Laboratory Co., Ltd.

Claims (7)

[Claims] 1. A plurality of semiconductor relays provided in a distributed manner in each power feeding path for distributing power supplied from a power source to a plurality of loads and feeding the plurality of loads. A relay unit that controls a power supply state, an overheat detection unit that detects overheat of the relay unit, and a power supply state to each load by controlling each semiconductor relay, while overheat is detected by the overheat detection unit. In this case, a control means for turning off or suppressing the power supply to at least a part of the loads, which are being driven, among the plurality of loads, which is determined according to a predetermined condition, is provided. In-vehicle power supply control device. 2. The overheat detecting means includes a temperature sensor for detecting the temperature of the relay unit, and a first overheat detecting section for detecting overheat of the relay unit based on a detection result of the temperature sensor. The vehicle-mounted power supply control device according to claim 1, wherein 3. The overheat detection unit detects a current value supplied to the load via the relay unit, and detects overheat of the relay unit based on a detection result of the current detection unit. The in-vehicle power supply control device according to claim 1, further comprising: 4. The overheat detection means includes an operation state detection unit that detects an operation state of each load based on a control signal of each load, and the relay unit based on a detection result of the operation state detection unit. The 3rd overheat detection part which estimates the amount of electric power supplied to each said load via the above, and detects the overheat of the said relay unit based on the amount of electric power, The 3rd overheat detection part of Claim 1 characterized by the above-mentioned. In-vehicle power supply control device. 5. The overheat detecting means, a temperature sensor for detecting a temperature of the relay unit, a current detecting section for detecting a current value supplied to the load via the relay unit, the temperature sensor and the The vehicle-mounted power supply control device according to claim 1, further comprising: a fourth overheat detection unit that detects overheating of the relay unit based on a detection result of the current detection unit. 6. The overheat detection means, a temperature sensor for detecting the temperature of the relay unit, an operation state detection unit for detecting an operation state of each load based on a control signal of each load, the operation state The amount of power supplied to each load via the relay unit is estimated based on the detection result of the detection unit, and overheat of the relay unit is detected based on the estimated amount of power and the detection result of the temperature sensor. The on-vehicle power supply control device according to claim 1, further comprising: 7. The control means, when the overheat is detected by the overheat detecting means, controls at least a part of loads of the plurality of loads which are being driven and which are determined according to a predetermined condition. 7. The in-vehicle power supply control device according to claim 1, wherein the power supply for the power supply is turned off after a lapse of a predetermined time from the occurrence of overheating.