CN111383869B

CN111383869B - Novel fuse box with large current and fuse fusing early warning function

Info

Publication number: CN111383869B
Application number: CN201811635124.1A
Authority: CN
Inventors: 周琦; 陈立志; 季金灿
Original assignee: Anbofu Electronics Suzhou Co ltd
Current assignee: Anbofu Electronics Suzhou Co ltd
Priority date: 2018-12-29
Filing date: 2018-12-29
Publication date: 2021-11-30
Anticipated expiration: 2038-12-29
Also published as: CN111383869A

Abstract

A fuse box is described. The fuse box includes a temperature sampling circuit and a microcontroller. The temperature sampling circuit is used for providing a first sampling value corresponding to the ambient temperature and a second sampling value corresponding to the temperature of the fuse metal electrode. Wherein the microcontroller is coupled with the temperature sampling circuit and configured to: obtaining an ambient temperature Ta and a metal electrode temperature Ts based on a first sampling value and a second sampling value obtained from a temperature sampling circuit; and calculating the average current I flowing through the fuse in real time based on Ta and Ts.

Description

Novel fuse box with large current and fuse fusing early warning function

Technical Field

The invention relates to a fuse box, in particular to a novel fuse box which is used on a vehicle and has a high-current and fuse fusing early warning function.

Background

With the rapid development of intelligent driving technology and new energy automobiles, more and more electronic devices are applied to automobiles, so that it is important to protect the safety work of all vehicle-mounted electronic devices.

Aiming at the condition of large-current fault in a line or a load, in order to ensure the service life of the load and the safety of a wire harness, the current electrical design usually adopts a method that a fuse is connected in a loop in series, and when the fault current is greater than the fuse fusing value, the fuse is fused and disconnected, so that the current is prevented from continuously increasing, and the load and the wire harness are protected. Automotive fuses are typically installed uniformly in a fuse box for easy troubleshooting and repair. However, the current vehicle-mounted fuse box design has the following two problems:

1. when a large current fault occurs but the fuse is not yet blown, the fuse box is not fed back to a driver, which becomes very dangerous during the running of the vehicle, because the driver cannot know that the fuse is about to be blown, and some functions of the vehicle will be lost.

2. Because of the theory of operation of fuse is that the electric current increases, and fuse temperature risees, and the protection is just fused to the fuse after the temperature risees fusing temperature, so under low temperature environment, the fuse needs the more electric current than the normal atmospheric temperature just can fuse, if fault current I satisfies following condition:

i Normal temperature fusing Current < I Fault Current < I Low temperature fusing Current

The fuse does not blow immediately for a short time, but the fault current may already be large enough to damage the device or shorten the device life. Current fuse box designs have no corresponding protection mechanism for such fault conditions.

Disclosure of Invention

The invention provides a fuse box. The fuse box includes a temperature sampling circuit and a microcontroller. The temperature sampling circuit is used for providing a first sampling value corresponding to the ambient temperature and a second sampling value corresponding to the temperature of the fuse metal electrode. Wherein the microcontroller is coupled with the temperature sampling circuit and configured to: obtaining an ambient temperature Ta and a metal electrode temperature Ts based on a first sampling value and a second sampling value obtained from a temperature sampling circuit; and calculating the average current I flowing through the fuse in real time based on Ta and Ts.

The temperature sampling circuit is further designed to provide temperature sampling based on the thermistor. More specifically, the temperature sampling circuit includes a first voltage-dividing sampling circuit having a first thermistor disposed away from the heat source, and a second voltage-dividing sampling circuit having a second thermistor disposed in the vicinity of the fuse metal electrode, wherein the microcontroller reads a voltage-dividing value on the first thermistor as a first sample value, reads a voltage-dividing value on the second thermistor as a second sample value, and calculates a resistance value Rt1 of the first thermistor and a resistance value Rt2 of the second thermistor based on the voltage-dividing principle.

The microcontroller is further designed to sample the sampling circuit via the AD port and to send information out via the CAN bus circuit. Further, the microcontroller obtains an environmental temperature value Ta based on the Rt1 and obtains a metal electrode temperature Ts based on the Rt2 based on a prestored thermistor R-T relation. Thereafter, the microcontroller calculates the average current I through the fuse by the following equation:

Ta+I²*R*K＝Ts

wherein R is the internal resistance of the fuse metal electrode, and K is the thermal resistance of the fuse

The microcontroller further calculates the fusing time T based on:

Q＝I²*T

where Q is the heat of fusion value of the fuse corresponding to the temperature Ts.

Further, the microcontroller may be configured to: and when the fusing time T calculated in real time is less than a specific threshold value, sending an early warning message.

To be able to function effectively under low temperature conditions, the microcontroller may be further configured to: identifying an ambient low temperature state, the ambient low temperature state being defined as an ambient temperature value Ta being below a predetermined temperature threshold; detecting a low temperature fault current condition (fuse normal temperature fusing current < average current I flowing through the fuse < fuse low temperature fusing current) in response to identifying the ambient low temperature condition; and sending an alarm message in response to detecting the low temperature fault current condition.

From the above description, typical implementations of the invention have the following advantages:

1. the average current of the line can be detected in real time, the fuse fusing time can be obtained according to the average current of the line, and early warning information is timely sent out when the fuse is about to be fused, so that the driving safety is enhanced.

2. When a high-current fault occurs on a circuit under a low-temperature condition, the fuse box can also identify the fault state in time and send alarm information in time, so that the load is protected.

3. The device and the process used in the design have low cost and are convenient to realize.

Drawings

Advantages of the invention will be readily appreciated and better understood by reference to the following detailed description when considered in connection with the accompanying drawings. In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. Some embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which:

fig. 1 illustrates a block diagram of a novel fuse box according to an embodiment.

Fig. 2 illustrates an illustrative deployment of placing a thermistor near a metal electrode of a fuse.

Detailed Description

In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of some example embodiments. It will be apparent, however, to one skilled in the art that the present disclosure may be practiced without these specific details.

Referring to the accompanying drawings, FIG. 1 illustrates a block diagram of a novel fuse box according to an embodiment. As shown in fig. 1, an exemplary fuse box may be comprised of 4 sections: a temperature sampling circuit 1, a Microcontroller (MCU)2, a Controller Area Network (CAN) bus circuit 3, and a fuse (not shown in fig. 1). More specifically, the temperature sampling circuit 1 may include a first sampling circuit including a thermistor circuit Rt1 and a resistor R1, and a second sampling circuit including a thermistor circuit Rt2 and a resistor R2. MCU 2 may include one or more analog-to-digital (AD) ports. In this embodiment, all of the devices may be mounted on the same Printed Circuit Board (PCB). However, those skilled in the art will appreciate that in other embodiments, the devices may be logically integrated by other coupling means to achieve the same functionality, and are not necessarily limited to the arrangement of the present embodiments.

Therein, the temperature sampling circuit 1 may be coupled to the MCU 2 to provide one or more sampled values to the MCU 2. In this embodiment, the first sampling circuit and the second sampling circuit in the temperature sampling circuit 1 may be respectively coupled to corresponding AD ports in the MCU 2. The MCU 2 may be coupled to the CAN bus circuit 3 to send warning messages to the driver via the CAN bus circuit 3.

In this embodiment, the temperature sampling circuit 1 may provide temperature sampling based on a thermistor. As shown in fig. 1, the first sampling circuit may include a thermistor Rt1 and a resistor R1, and the thermistor Rt1 may be placed at a position far from the heat source so that the ambient temperature can be accurately detected without being disturbed by the temperatures of other heat sources. Wherein the resistor R1 is used for dividing the voltage with the thermistor Rt1, as shown in fig. 1, the first sampling circuit can be powered by analog Voltage (VDDA), and since the resistance of the thermistor Rt1 varies according to the change of the environmental temperature, under the voltage division of the thermistor Rt1 and R1, the voltage data V1 (i.e., sampling value) read from the first sampling circuit by the AD port of the MCU can also vary according to the change of the environmental temperature. Similarly, the second sampling circuit may include a thermistor Rt2 and a resistor R2, and the thermistor Rt2 may be placed near the metal electrode of the fuse to detect the temperature of the metal electrode. For clarity, fig. 2 illustrates an illustrative deployment in which the thermistor Rt2 is placed near the metal electrode of the fuse, but the specific deployment is not so limited. In the second sampling circuit, the resistor R2 functions to divide the voltage with the thermistor Rt2, as shown in fig. 1, the second sampling circuit may be powered by VDDA, since the resistance value of the thermistor Rt2 may vary according to the change of the temperature of the fuse metal electrode, and the voltage data V2 (i.e., the sampled value) read from the second sampling circuit by the AD port of the MCU may also vary according to the change of the temperature of the fuse metal electrode under the voltage division function of the thermistor Rt2 and R2. Generally, the voltage level of VDDA and the resistance levels of R1 and R2 are known or may be known by looking up specifications or other means. It is to be understood that although the present embodiment illustrates a specific implementation of the temperature sampling circuit, this is for illustrative purposes only and is not limiting.

In this embodiment, the MCU 2 can sample the temperature sampling circuit 1 through one or more AD ports. Among other things, one or more AD ports may convert voltage data (i.e., sampled values) from the temperature sampling circuit 1 from analog data to digital data for processing by the MCU 2. Thereafter, since the values of VDDA and R1 are known, MCU 2 can obtain the resistance value of Rt1 under specific conditions according to the read voltage data and the voltage division principle, as shown in the following formula:

Rt1＝(R1*VDDA)/V1-R1

similarly, the resistance value of Rt2 can be obtained:

Rt2＝(R2*VDDA)/V2-R2

subsequently, the MCU 2 can obtain an ambient temperature value Ta and a fuse metal electrode temperature value Ts from the obtained resistance values of the thermistors Rt1 and Rt2 and the R-T (resistance-temperature) relationship of the thermistors, respectively. Wherein the R-T relationship may be pre-stored by the MCU 2 to a location accessible to the MCU 2 (such as in memory). After obtaining the ambient temperature value Ta and the metal electrode temperature value Ts, the MCU 2 may calculate an average current I flowing through the fuse based on the following formula (i.e., thermal power consumption calculation formula):

Ta+I²*R*K＝Ts

wherein R is the internal resistance of the fuse metal electrode, K is the thermal resistance of the fuse, both of which can be found from the fuse specification. Thus, the average current I flowing through the fuse can be calculated.

Further, the fusing time T of the fuse can be determined according to the calculated average current I and the melting heat energy value of the fuse, and the determination can be represented by the following formula:

Q＝I²*T

where Q is the heat of fusion value, which is a constant for the fuse at a particular temperature, and in this case Q corresponds to a known ambient temperature Ts.

As such, the MCU 2 may transmit an early warning message, such as a visual message (such as a warning on a display) and an audible message (such as a warning issued by a speaker), to the driver through the CAN bus circuit 3 when the fusing time T is less than a certain threshold. Therefore, the problem of lack of a feedback mechanism in the prior art is solved. It is to be understood that while the present embodiment illustrates a specific implementation of a microcontroller, this is for illustrative purposes only and is not limiting.

In the present embodiment, the CAN bus circuit 3 may be any suitable circuitry that conforms to the CAN communication protocol, as is well known to those skilled in the art. According to the characteristics of the CAN communication protocol, the CAN bus circuit 3 CAN realize real-time and reliable communication among all devices in the circuit. For example, in the present embodiment, the CAN bus circuit 3 may cause any suitable device (such as a display, a speaker, etc.) connected to the CAN bus circuit 3 to issue an early warning message in real time based on the processing result of the MCU 2 to alert the driver that a malfunction has occurred. It is to be understood that although the present embodiment transmits the warning message through the CAN bus circuit, this is only one preferred embodiment and is not limited thereto. For example, the MCU 2 may be directly coupled to a device (such as a display, speaker, etc.) capable of sending the warning message.

In a further embodiment, the MCU 2 may be configured to identify an ambient low temperature state, wherein the ambient low temperature state may be defined as an ambient temperature value Ta below a predetermined temperature threshold. When a low temperature state is identified, the MCU 2 may detect a fault current condition under the current temperature conditions, i.e., if the average current flowing through the fuse satisfies: the fuse normal temperature fusing current < the average current I flowing through the fuse < the fuse low temperature fusing current, the MCU 2 can send alarm information to remind a driver. In this way, even under low temperature conditions, the embodiment of the invention can still remind the driver of the occurrence of a large-current fault so as to avoid damaging equipment or shortening the service life of the equipment.

It will be readily appreciated that the fuse block disclosed herein is not only applicable to the automotive field, but may be used in any other suitable field of electrical systems, industrial systems, automotive control systems, etc. that are susceptible to high current faults.

The foregoing detailed description includes references to the accompanying drawings, which form a part hereof. The drawings show, by way of illustration, specific embodiments which can be practiced.

In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of "at least one" or "one or more. In this document, the term "or" is used to refer to a non-exclusive or, such that "a or B" includes "a but not B," "B but not a," and "a and B," unless otherwise indicated. In the appended claims, the terms "including" and "in which" are used as the plain-english equivalents of the respective terms "comprising" and "wherein". Furthermore, in the following claims, the terms "comprising" and "including" are open-ended, that is, a system, device, article, or process that includes elements in the claims in addition to those elements recited after such terms are still considered to be within the scope of that claim. Furthermore, in the appended claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to indicate a numerical order of their objects. The term "coupled" is defined as connected, although not necessarily directly, and not necessarily mechanically.

The above description is intended to be illustrative, and not restrictive. Other embodiments, such as those implemented by one of ordinary skill in the art after perusal of the above description, may also be used. The abstract allows the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. Moreover, in the foregoing detailed description, various features may be grouped together to streamline the disclosure. However, the claims may not recite each feature disclosed herein because features of an embodiment may be a subset of the features. Further, embodiments may include fewer features than those disclosed in a particular example. Thus the following claims are hereby incorporated into the detailed description, with one claim standing on its own as a separate embodiment. The scope of the embodiments disclosed herein should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A fuse block, comprising:

the temperature sampling circuit is used for providing a first sampling value corresponding to the ambient temperature and a second sampling value corresponding to the temperature of the fuse metal electrode; and

a microcontroller coupled with the temperature sampling circuit, the microcontroller configured to:

obtaining an ambient temperature value Ta and a metal electrode temperature Ts based on a first sampling value and a second sampling value obtained from the temperature sampling circuit,

based on the Ta and Ts, calculating the average current I flowing through the fuse in real time according to the following formula:

Ta+I²*R*K＝Ts

wherein R is the internal resistance of the fuse metal electrode, and K is the fuse thermal resistance.

2. The fuse block of claim 1, wherein the temperature sampling circuit provides temperature sampling based on a thermistor.

3. The fuse block of claim 2, wherein the temperature sampling circuit comprises: the microcontroller reads a voltage division value on the first thermistor as the first sampling value, reads a voltage division value on the second thermistor as the second sampling value, and calculates a resistance value Rt1 of the first thermistor and a resistance value Rt2 of the second thermistor based on a voltage division principle.

4. The fuse block of claim 2 or 3, wherein the microcontroller samples the temperature sampling circuit through an AD port and sends out information through a CAN bus circuit.

5. A fuse block as claimed in claim 3 wherein the microcontroller derives the ambient temperature value Ta based on Rt1 and the metal electrode temperature Ts based on Rt2 based on a pre-stored thermistor R-T relationship.

6. The fuse block of claim 1, wherein the microcontroller determines a fusing time T of the fuse based on the average current I and a heat of fusion value of the fuse.

7. The fuse block of claim 6, wherein the microcontroller calculates the fusing time T based on:

Q＝I²*T

wherein Q is the heat of fusion value of the fuse corresponding to said temperature Ts.

8. The fuse block of claim 6 or 7, wherein the microcontroller is further configured to: and when the fusing time T calculated in real time is less than a specific threshold value, sending an early warning message.

9. The fuse box of claim 1, wherein the microcontroller is further configured to:

identifying an ambient low temperature state defined as the ambient temperature value Ta being below a predetermined temperature threshold;

in response to identifying an ambient low temperature condition, detecting a low temperature fault current condition: the normal-temperature fusing current of the fuse is less than the average current I flowing through the fuse and less than the low-temperature fusing current of the fuse;

in response to detecting the low temperature fault current condition, an alarm message is sent.