TEMPERATURE MEASURING DEVICE

Abstract

Temperature sensing device (60) with: a first temperature sensor (62) which is arranged adjacent to a first part in a DC circuit (40), a second temperature sensor (64) which is arranged adjacent to a second part in the DC circuit (40), wherein the second part has a higher potential than the first part, a sensor input circuit (80) which connects a first terminal of the first temperature sensor (62) and a second terminal of the second temperature sensor (64) to a power supply voltage line (66) and which connects a third terminal of the first temperature sensor (62) and a fourth terminal of the second temperature sensor (64) to a reference voltage line (68), and a protection circuit (90) provided between the first and second temperature sensors (62, 64) and the sensor input circuit (80), wherein the protection circuit (90) has: a first sensor connection path (91) which includes a first overcurrent protection element (100) and connects the first terminal of the first temperature sensor (62) to the power supply voltage line (66) of the sensor input circuit (80), a second sensor connection path (93) which has a second overcurrent protection element (100) and connects the second terminal of the second temperature sensor (64) to the power supply voltage line (66) of the sensor input circuit (80), a third sensor connection path (92) which includes a third overcurrent protection element (100) and connects the third terminal of the first temperature sensor (62) to the reference voltage line (68) of the sensor input circuit (80), a fourth sensor connection path (94) which includes a fourth overcurrent protection element (100) and connects the fourth terminal of the second temperature sensor (64) to the reference voltage line (68) of the sensor input circuit (80), a rectifying element (102) that connects the first sensor connection path (91) to the reference voltage line (68) in a section between the first overcurrent protection element (100) and the sensor input circuit (80), wherein the first sensor connection path (91) has a normal voltage that is higher than the reference voltage line (68), and an overvoltage protection element (104) that connects the second sensor connection path (93) to the reference voltage line (68) in a section between the second overcurrent protection element (100) and the sensor input circuit (80), wherein the second sensor connection path (93) has a normal voltage that is higher than the reference voltage line (68), wherein the first overcurrent protection element (100), the second overcurrent protection element (100), the third overcurrent protection element (100) and the fourth overcurrent protection element (100) are each an element that loses conductivity when a current exceeding a predetermined current value flows through it, the rectifying element (102) prevents a flow of current from the first sensor connection path (91) to the reference voltage line (68) and allows a flow of current from the reference voltage line (68) to the first sensor connection path (91), the surge protection element (104) electrically connects the second sensor connection path (93) to the reference voltage line (68) when a voltage of the second sensor connection path (93) exceeds a predetermined voltage value with respect to the reference voltage line (68), and the predetermined voltage value is higher than a maximum value of the normal voltage of the second sensor connection path (93) and lower than a potential difference between the first part and the second part, wherein the rectifying element (102) is a diode, the overvoltage protection element (104) is a Zener diode, an anode of the Zener diode is connected to the reference voltage line (68), a cathode of the Zener diode is connected to the second sensor connection path (93), and The breakdown voltage of the Zener diode is equal to the predetermined voltage value.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The invention relates to a temperature detection device. 2. Description of the state of the art

[0002] A motor drive system for a vehicle is described in Japanese patent application publication JP 2000-278802 A. This system includes a battery, a motor driven by electrical power from the battery, and an inverter that converts the electrical power between the battery and the motor. The positive and negative electrodes of the battery are connected to the inverter via relays.

[0003] JP 2009 / 099473 A discloses an abnormality detection device for an energy storage device. The device detects a potential of a block that is part of a battery pack, and calculates a temperature of the block based on a potential of a thermistor installed on the surface of the block. An abnormality is detected based on the potential of the thermistor and / or the potential of the block.

[0004] DE 10 2011 089 996 A1 discloses an on-board power system comprising a switching device controlled by a control unit. Pulse width modulation is performed, with the pulse width being adjustable according to the temperature of the switching device, which is detected by a temperature sensor.

[0005] DE 10 2007 028 929 B3 discloses a measuring sensor, in particular a temperature sensor for use in power electronics. The measuring sensor comprises a sensor element that is wired to a signal output via a signal line. The signal line is connected to ground via an overvoltage bypass that is blocked during normal operation but opens in the event of an overvoltage. Furthermore, a fuse is provided in the signal line. SUMMARY OF THE INVENTION

[0006] In a configuration such as the system described in JP 2000-278802 A, in which a battery or other direct current (DC) power supply is connected to an inverter or other load via relays, it is considered to monitor the temperatures of the respective relays, for example, to prevent the relays from overheating. In this case, a temperature sensing device capable of sensing the temperatures of the respective relays is required. This temperature sensing device may be configured using a plurality of temperature sensors and a sensor input circuit. Each temperature sensor is arranged adjacent to a corresponding one of the relays and outputs a detection signal corresponding to the temperature of the corresponding relay.By connecting the terminals of the temperature sensors to a power supply voltage line and / or a reference voltage line, the sensor input circuit supplies the necessary electrical power to the temperature sensors and suppresses noise that occurs in the detection signals. The detection signals of the temperature sensors are fed to a monitoring circuit, which includes a microprocessor, etc., via the sensor input circuit.

[0007] In the temperature detection device described above, there is a possibility of accidental continuity occurring between the temperature sensor and the relay, which are arranged adjacent to each other. In this regard, there is a potential difference caused by the DC power supply between the relay connected to a positive electrode of the DC power supply and the relay connected to a negative electrode of the DC power supply. Accordingly, with respect to such two relays, if accidental continuity occurs simultaneously between the temperature sensors and the relays, there is a possibility that a short-circuit current flows in a path extending from one of the temperature sensors through the sensor input circuit to the other temperature sensor. This is not limited to the case where the temperatures of a plurality of relays are detected.That is, even in the case where the temperatures of a plurality of elements other than relays having a potential difference are detected in a DC circuit, the same thing as described above may occur if unintentional continuities occur between the DC circuit and a plurality of temperature sensors at the same time.

[0008] It is an object of the invention to provide a technique that can protect a sensor input circuit when unintentional conductions occur simultaneously in a plurality of temperature sensors in a temperature detecting device that detects the temperatures of a plurality of elements in a DC circuit.

[0009] This object is achieved by a temperature detection device as defined in claim 1.

[0010] According to one embodiment of the invention, a temperature detection device is provided, comprising: a first temperature sensor arranged adjacent to a first part in a DC circuit; a second temperature sensor arranged adjacent to a second part in the DC circuit, the second part having a higher potential than the first part; a sensor input circuit connecting a first terminal of the first temperature sensor and a second terminal of the second temperature sensor to a power supply voltage line, and connecting a third terminal of the first temperature sensor and a fourth terminal of the second temperature sensor to a reference voltage line; and a protection circuit provided between the first and second temperature sensors and the sensor input circuit, the protection circuit comprising: a first sensor connection path,which has a first overcurrent protection element and connects the first terminal of the first temperature sensor to the power supply voltage line of the sensor input circuit; a second sensor connection path which has a second overcurrent protection element and connects the second terminal of the second temperature sensor to the power supply voltage line of the sensor input circuit; a third sensor connection path which has a third overcurrent protection element and connects the third terminal of the first temperature sensor to the reference voltage line of the sensor input circuit; a fourth sensor connection path which has a fourth overcurrent protection element and connects the fourth terminal of the second temperature sensor to the reference voltage line of the sensor input circuit; a rectification element,which connects the first sensor connection path to the reference voltage line in a section between the first overcurrent protection element and the sensor input circuit, wherein the first sensor connection path has a normal voltage higher than the reference voltage line; and an overcurrent protection element which connects the second sensor connection path to the reference voltage line in a section between the second overcurrent protection element and the sensor input circuit, wherein the second sensor connection path has a normal voltage higher than the reference voltage line, wherein the first overcurrent protection element, the second overcurrent protection element, the third overcurrent protection element, and the fourth overcurrent protection element are each an element that loses conductivity when a current exceeding a predetermined current value flows therethrough,The rectification element prevents current flow from the first sensor connection path to the reference voltage line and allows current flow from the reference voltage line to the first sensor connection path. The overvoltage protection element electrically connects the second sensor connection path to the reference voltage line when a voltage of the second sensor connection path with respect to the reference voltage line exceeds a predetermined voltage value, and the predetermined voltage value is higher than a maximum value of the normal voltage of the second sensor connection path and lower than a potential difference between the first part and the second part. The rectification element is a diode, and the overvoltage protection element is a Zener diode, wherein an anode of the Zener diode is connected to the reference voltage line, and a cathode of the Zener diode is connected to the second sensor connection path.and a breakdown voltage of the Zener diode is equal to the predetermined voltage value.,

[0011] The normal voltage referred to herein may be a voltage that occurs during normal operation of the temperature sensing device and may be fixed at a predetermined value or may vary within a predetermined range. The normal voltages of the first sensor connection path and the second sensor connection path may be determined primarily by the sensor input circuit.

[0012] According to the configuration described above, the sensor input circuit is protected.

[0013] Advantageous embodiments are specified in the dependent patent claims.

[0014] The DC circuit may include a DC power supply, the first part may be a first relay connected to a negative electrode of the DC power supply, and the second part may be a second relay connected to a positive electrode of the DC power supply.

[0015] The DC circuit may include a DC power supply, and the first part may be the DC power supply.

[0016] The DC circuit may include a DC power supply, and the second part may be the DC power supply.

[0017] The DC circuit may include a DC power supply in which a plurality of power supplies are connected in series, the first part may be a negative side of the DC power supply, and the second part may be a positive side of the DC power supply. SHORT DESCRIPTION OF THE DRAWING

[0018] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, in which like reference numerals denote like elements. Shown are: Fig. 1 is a block diagram schematically illustrating the configuration of a hybrid vehicle 10, Fig. 2 is a block diagram schematically illustrating the configuration of a power converter circuit 30, Fig. 3 is a circuit diagram schematically illustrating the configuration of a temperature detecting device 60. Fig. 4 is a diagram illustrating a path of a short-circuit current SC flowing from a specified second sensor connection path 93 to a specified first sensor connection path 91, Fig. 5 is a diagram illustrating a path of a short-circuit current SC flowing from the specified second sensor connection path 93 to the other first sensor connection path 92, Fig. 6 is a diagram illustrating a path of a short-circuit current SC flowing from the other second sensor connection path 94 to the specific first sensor connection path 91, Fig. 7 is a diagram illustrating a path of a short-circuit current SC flowing from the other sensor connection path 94 to the other first sensor connection path 92, Fig. 8 is a diagram illustrating a temperature sensing device 60, of which a second temperature sensor 64 is arranged in a battery 38, Fig. 9 is a diagram illustrating a temperature sensing device 60, of which a first temperature sensor 62 and a second temperature sensor 64 are both arranged in a battery 38, and Fig. 10 is a diagram illustrating a temperature detecting device 60 in which a third temperature sensor 65 is added. DETAILED DESCRIPTION OF EMBODIMENTS

[0019] With reference to the drawings, a hybrid vehicle 10 according to an embodiment is described. As shown in Fig. 1, the hybrid vehicle 10 includes a vehicle body 12 and four wheels 14 and 16 rotatably supported on the vehicle body 12. The four wheels 14 and 16 include a pair of drive wheels 14 and a pair of driven wheels 16. The pair of drive wheels 14 are connected to an output shaft 20 via a differential gear 18. The output shaft 20 is rotatably supported on the vehicle body 12. As an example, the pair of drive wheels 14 are front wheels located at the front of the vehicle body 12, whereas the pair of driven wheels 16 are rear wheels located at the rear of the vehicle body 12. The drive wheels 14 are arranged coaxially with each other, and the driven wheels 16 are also arranged coaxially with each other.

[0020] The hybrid vehicle 10 further includes an engine 22, a first motor generator (1MG) 24 and a second motor generator (2MG) 26.

[0021] Hereinafter, the first motor generator 24 is simply referred to as the first motor 24, and the second motor generator 26 is simply referred to as the second motor 26. The engine 22 is a displacement internal combustion engine and outputs power by burning fuel. The engine 22 is connected to the output shaft 20 and the first motor 24 via a planetary gear mechanism 28. The planetary gear mechanism 28 is a type of power distribution mechanism and distributes the power output from the engine 22 to the output shaft 20 and the first motor 24. The engine 22 is a power source for driving the drive wheels 14 and is also a power source for driving the first motor 24, which functions as a generator.

[0022] The first motor 24 and the second motor 26 are each a three-phase motor generator having a U phase, a V phase, and a W phase. As described above, the first motor 24 is connected to the engine 22 via the planetary gear mechanism 28. The first motor 24 is mainly used as a generator that generates electric power using the power from the engine 22. The first motor 24 is also used as a starter motor for starting the engine 22. The second motor 26 is connected to the output shaft 20 and is used as a power source for driving the drive wheels 14. The second motor 26 is also used as a generator that generates electric power using the power from the output shaft 20, for example, when the hybrid vehicle 10 is decelerated.

[0023] As it is in Fig. 1 and Fig. 2, the hybrid vehicle 10 further includes a power converter circuit 30 and a battery 38. The battery 38 is electrically connected to the first motor 24 and the second motor 26 via the power converter circuit 30. The battery 38 is a DC power supply that includes a plurality of secondary battery cells 38c and is capable of repeated charging and discharging. The type of the secondary cells 38c is not particularly limited and may be, for example, a lithium battery or a nickel-hydrogen battery. As an example, according to this embodiment, the rated voltage of the battery 38 is about 200V, while the rated voltages of the first motor 24 and the second motor 26 are each about 600V. That is, the rated voltage of the battery 38 is lower than the rated voltage of each of the first motor 24 and the second motor 26.Specific values ​​of the rated voltages of the battery 38, the first motor 24 and the second motor 26 as well as their magnitude ratio are not particularly restricted.

[0024] As it is in Fig. 2, the power converter circuit 30 includes a DC-DC converter 32, a first inverter 34, and a second inverter 36. The DC-DC converter 32 is a DC-DC converter capable of stepping up and down voltage. The battery 38 is connected to the first motor 24 via the DC-DC converter 32 and the first inverter 34. When the first motor 24 functions as a motor, DC power from the battery 38 is stepped up by the DC-DC converter 32, then converted to AC power by the inverter 34, and then supplied to the first motor 24. In contrast, when the first motor 24 functions as a generator, the AC power from the first motor 24 is converted to DC power by the first inverter 34, then stepped down by the DC-DC converter 32, and then supplied to the battery 38.Similarly, the battery 38 is connected to the second motor 26 via the DC-DC converter 32 and the second inverter 36. When the second motor 26 functions as a motor, DC power from the battery 38 is stepped up by the DC-DC converter 32, then converted into AC power by the second inverter 36, and then supplied to the second motor 26. In contrast, when the second motor 26 functions as a generator, AC power from the second motor 26 is converted into DC power by the second inverter 26, then stepped down by the DC-DC converter 32, and then supplied to the battery 38. The configuration of the power converter circuit 30 according to this embodiment is merely an example, and the configuration of the power converter circuit 30 can be changed as appropriate according to the configurations of the battery 38, the first motor 24, and the second motor 26.For example, if the rated voltage of the battery 38 is the same as the rated voltage of each of the first motor 24 and the second motor 26, the DC-DC converter 32 is not necessarily required.

[0025] As it is in Fig. 1 and Fig. As shown in Figure 2, the hybrid vehicle 10 includes a first relay 42 and a second relay 44. The first relay 42 is provided in a first power line 40a that connects a negative electrode 38a of the battery 38 and the power converter circuit 30, and functions to cause the first power line 40a to be electrically continuous or open. The second relay 44 is provided in a second power line 40b that connects a positive electrode 38b of the battery 38 and the power converter circuit 30, and functions to cause the second power line 40b to be electrically continuous or open. The battery 38, the first power line 40a, and the second power line 40b form a DC circuit 40 in which a DC current flows when the second relay 44 has a higher potential than the first relay 42.Normally, when the hybrid vehicle 10 is in use, the first relay 42 and the second relay 44 are closed, so that the battery 38 is electrically connected to the power converter circuit 30. In contrast, when the hybrid vehicle 10 is not in use, the first relay 42 and the second relay 44 are open, so that the battery 38 and the power converter circuit 30 are electrically isolated from each other. Although not particularly limited, the first relay 42 and the second relay 44 according to this embodiment are each an electromagnetic relay that opens and closes its contact by an electromagnet.

[0026] As it is in Fig. As shown in Figure 1, the hybrid vehicle 10 further includes a hybrid control unit (hybrid vehicle ECU (ECU: electronic control unit)) 50, an engine control unit (engine ECU) 52, a motor control unit (MG-ECU) 54, and a battery control unit (battery ECU) 58. These control units constitute a control part that monitors and controls the operation of the hybrid vehicle 10. The motor control unit 54 mainly monitors and controls the operation of the power converter circuit 30. Accordingly, the operation of the first motor 24 and the operation of the second motor 26 are controlled by the motor control unit 54. The battery control unit 58 mainly monitors and controls the operation of the battery 38.The hybrid control unit 50 is a host control unit communicatively connected to the engine control unit 52, the motor control unit 54, and the battery control unit 58, and supplies operating commands to these control units. For example, according to a user's accelerator pedal operation, a speed of the hybrid vehicle 10, etc., the hybrid control unit 50 supplies an operating command including a target torque value to each of the control unit 52, the motor control unit 54, and the battery control unit 58. Furthermore, the hybrid control unit 50 is electrically connected to the first relay 42 and the second relay 54 and controls the operation of the first relay 42 and the second relay 44.Alternatively, the operation of the first relay 42 and the operation of the second relay 44 may be controlled by the battery control unit 58 or another control unit instead of the hybrid control unit 50.

[0027] With the above-described configuration, in the hybrid vehicle 10 according to this embodiment, the electric power charged in the battery 38 is supplied to the first motor 24 or the second motor 26 via the power conversion circuit 30, or electric power generated by the first motor 24 or the second motor 26 is supplied to the battery 38 via the power conversion circuit 30. In either case, current flows through the first relay 42 and the second relay 44, so the temperatures of the first relay 42 and the second relay 44 rise. At this time, if the temperature of the first relay 42 or the second relay 44 rises excessively, a failure of the first relay 42 or the second relay 44, such as contact welding, may occur.In view of this, in order to monitor the temperatures of the first relay 42 and the second relay 44, the hybrid vehicle 10 according to this embodiment is provided with a temperature detecting device 60, which will be described below.

[0028] As it is in Fig. 3, the temperature detection device 60 includes a first temperature sensor 62, a second temperature sensor 64, a monitoring circuit 70, a sensor input circuit 80, and a protection circuit 90. The first temperature sensor 62 is a sensor that detects the temperature of the first relay 42. The first temperature sensor 62 is arranged adjacent to the first relay 42 and outputs a detection signal corresponding to the temperature of the first relay 42. The second temperature sensor 64 is a sensor that detects the temperature of the second relay 44. The second temperature sensor 64 is arranged adjacent to the second relay 44 and outputs a detection signal corresponding to the temperature of the second relay 44. Specific configurations of the first temperature sensor 62 and the second temperature sensor 64 are not particularly limited.As an example, the first temperature sensor 62 and the second temperature sensor 64 according to this embodiment are each a thermistor whose resistance value changes according to the temperature.

[0029] The detection signals from the first temperature sensor 62 and the second temperature sensor 64 are respectively supplied to the monitoring circuit 70 via the protection circuit 90 and the sensor input circuit 80. As an example, the monitoring circuit 70 according to this embodiment is configured using a microcomputer (or microprocessor) and is disposed in the battery control unit 58. The position and configuration of the monitoring circuit 70 are not particularly limited, and part or all of the monitoring circuit 70 may be provided in another control unit or other circuit unit. The monitoring circuit 70 is connected to a power supply voltage line 66 and a reference voltage line 68 in the battery control unit 58. At this time, the reference voltage line 68 is electrically connected to ground so that its potential is maintained at 0 V.The power supply voltage line 66 is connected to a power supply circuit (not shown) of the battery control unit 58 so that its potential is maintained at, for example, 5 V.

[0030] The sensor input circuit 80 is provided between the first and second temperature sensors 62 and 64 and the monitoring circuit 70. Although the sensor input circuit 80 is provided in the battery control unit 58 according to this embodiment, part or all of the sensor input circuit 80 may be provided in another control unit or other circuit unit. The sensor input circuit 80 connects terminals 62a and 62b of the first temperature sensor 62 and terminals 64a and 64a of the second temperature sensor 64 to the power supply voltage line 66 and / or the reference voltage line 68. Accordingly, the sensor input circuit 80 supplies necessary electrical power to the first temperature sensor 62 and the second temperature sensor 64 and suppresses noise that occurs in detection signals from the first and second temperature sensors 62 and 64.A specific configuration of the sensor input circuit 80 is not particularly limited. For example, in the sensor input circuit 80 according to this embodiment, one terminal 62a of the first temperature sensor 62 is connected to the power supply voltage line 66 via a pull-up resistor 82a and to the reference voltage line 68 via two capacitors 84a and 88a. Furthermore, one terminal 62a of the first temperature sensor 62 is connected to the monitoring circuit 70 via a resistor 86a. In contrast, the other terminal 62b of the first temperature sensor 62 is directly connected to the reference voltage line 86 via no resistor, capacitor, or the like in the sensor input circuit 80. As described above, the first temperature sensor 62 according to this embodiment is the thermistor.Therefore, according to the sensor input circuit 80 described above, the voltage between the terminals 62a and 62b of the first temperature sensor 62 changes according to the temperature of the first relay 42. As a result, a detection signal having a voltage value corresponding to the temperature of the first relay 42 is supplied to the monitoring circuit 70 from the sensor input circuit 80.

[0031] Similarly, in the sensor input circuit 80, one terminal 64a of the second temperature sensor 64 is connected to the power supply voltage line 66 via a pull-up resistor 82b and is connected to the reference voltage line 68 via two capacitors 84b and 88b. Furthermore, one terminal 64a of the second temperature sensor 64 is connected to the monitoring circuit 70 via a resistor 86b. In contrast, the other terminal 64b of the second temperature sensor 64 is directly connected to the reference voltage line 64 via no resistor, capacitor, or the like in the sensor input circuit 80. As described above, according to this embodiment, the second temperature sensor 64 is also the thermistor.Therefore, according to the sensor input circuit 80 described above, the voltage between the terminals 64 and 64b of the second temperature sensor 64 changes according to the temperature of the second relay 44. As a result, a detection signal having a voltage value corresponding to the temperature of the second relay 44 is supplied from the sensor input circuit 80 to the monitoring circuit 70.

[0032] The monitoring circuit 70 detects overheating of the first relay 42 by monitoring the detection signal of the first temperature sensor 62 and detects overheating of the second relay 44 by monitoring the detection signal of the second temperature sensor 64. Upon detecting overheating of the first relay 42 or the second relay 44, the monitoring circuit 70 sends a predetermined alarm signal to the hybrid control unit 50. In response to receiving the alarm signal, the hybrid control unit 50 performs a predetermined protective operation to prevent further overheating of the first relay 42 or the second relay 44. For example, as one of the protective operations, the hybrid control unit 50 limits a target torque value to be instructed to the motor control unit 54.Consequently, the current flowing through the first relay 42 and the second relay 44 decreases to suppress temperature rise of the first relay 42 and the second relay 44, so that a failure such as welding of the first relay 42 and the second relay 44 is prevented.

[0033] In the temperature detecting device 60 according to this embodiment, since the first temperature sensor 62 is disposed adjacent to the first relay 42, there is a possibility of accidental continuity occurring between the first temperature sensor 62 and the first relay 42. Similarly, there is a possibility of accidental continuity also occurring between the second temperature sensor 64 and the second relay 44. Meanwhile, when the accidental continuity between the first temperature sensor 62 and the first relay 42 and the accidental continuity between the second temperature sensor 64 and the second relay 64 occur simultaneously, there is a possibility that a short-circuit current flows from the DC circuit 40 (particularly, the battery 38) into the sensor input circuit 80, so that the sensor input circuit 80 is damaged.Therefore, in the temperature detection device 60 according to this embodiment, the protection circuit 90 is provided to protect the sensor input circuit 80. The protection circuit 90 is provided between the first and second temperature sensors 62 and 64 and the sensor input circuit 80. Although the protection circuit 90 according to this embodiment is provided in the battery control unit 58, part or all of the protection circuit 90 may be provided in another control unit or another circuit unit.

[0034] The protection circuit 90 includes a plurality of first sensor connection paths 91 and 92, a plurality of second sensor connection paths 93 and 94, a first diode 102, and a second diode 104. Each of the first sensor connection paths 91 and 92 includes at least one overcurrent protection element 100. The first sensor connection paths 91 and 92 connect the terminals 62a and 62b of the first temperature sensor 62 to the sensor input circuit 80, respectively. Similarly, the second sensor connection paths 93 and 94 each include at least one overcurrent protection element 100 and connect the terminals 64a and 64b of the second temperature sensor 64 to the sensor input circuit 80, respectively. Each overcurrent protection element 100 is an element that loses conductivity when a current exceeding a predetermined current value flows therethrough.This predetermined current value is set to be greater than a current value flowing in each of the sensor connection paths 91 to 94 during normal operation of the temperature sensing device 60. As an example, the overcurrent protection element 100 according to this embodiment is a fuse that blows when the current exceeding the predetermined current value flows therethrough. Alternatively, the overcurrent protection element 100 may be another type of interrupting element or interrupting device.

[0035] Of the first sensor connection paths 91 and 92, the normal voltage of the first sensor connection path 91 connected to one terminal 62a of the first temperature sensor 62 becomes higher than the normal voltage of the reference voltage line 68. In contrast, the normal voltage of the first sensor connection path 92 connected to the other terminal 62b of the first temperature sensor 62 becomes equal to the normal voltage of the reference voltage line 68. The normal voltage referred to herein is a voltage that may occur in the normal operation of the temperature detection device 60 and is fixed at a predetermined value or changes within a predetermined range.In this specification, for convenience, the first sensor connection path 91 whose normal voltage is higher than the reference voltage line 68 is referred to as the specific first sensor connection path 91 to distinguish it from the other first sensor connection path 92. The specific first sensor connection path 91 is connected to the reference voltage line 68 via the first diode 102 in a portion between the overcurrent protection element 100 and the sensor input circuit 80.

[0036] The anode of the first diode 102 is connected to the reference voltage line 68. The cathode of the first diode 102 is connected to the specific first sensor connection path 91. Consequently, the first diode 102 prevents the flow of current from the specific first sensor connection path 91 to the reference voltage line 68 and allows the flow of current from the reference voltage line 68 to the specific first sensor connection path 91. The breakdown voltage of the first diode 102 is higher than a maximum value of the normal voltage of the specific first sensor connection path 91. With this configuration, there is no possibility that, during normal operation of the temperature sensing device 60, the specific first sensor connection path 91 is electrically connected to the reference voltage line 68 via the first diode 102.Accordingly, a detection signal from the first temperature sensor 62 is correctly supplied to the monitoring circuit 70 via the sensor input circuit 80. Conversely, when the potential of the reference voltage line 68 becomes higher than that of the specific first sensor connection path 91, the reference voltage line 68 is electrically connected to the specific first sensor connection path 91 via the first diode 102. The first diode 102 may be a Zener diode or may be another type.

[0037] Of the second sensor connection paths 93 and 94, the normal voltage of the second sensor connection path 93 connected to one terminal 64a of the second temperature sensor 64 becomes higher than the normal voltage of the reference voltage line 68. In contrast, the normal voltage of the second sensor connection path 94 connected to the other terminal 64b of the second temperature sensor 64 becomes equal to the normal voltage of the reference voltage line 68. In this specification, the second sensor connection path 93 whose normal voltage is higher than the reference voltage line 68 is referred to as the specific second sensor connection path 93 for convenience in distinguishing it from the other second sensor connection path 94. The second specific sensor connection path 93 is connected to the reference voltage line 68 via the second diode 104 in a portion between the overcurrent protection element 100 and the sensor input circuit 80.The second diode 104 is an example of an overvoltage protection element.

[0038] The anode of the second diode 104 is connected to the reference voltage line 64. The cathode of the second diode 104 is connected to the specific second sensor connection path 93. The breakdown voltage of the second diode 104 is higher than a maximum value of the normal voltage and the specific second sensor connection path 93, but is lower than a potential difference between the first relay 42 and the second relay 44. With this configuration, there is no possibility that the specific second sensor connection path 93 is electrically connected to the reference voltage line 68 via the second diode 104 during normal operation of the temperature detection device 60. Accordingly, a detection signal of the second temperature sensor 64 is correctly supplied to the monitoring circuit 70 via the sensor input circuit 80.On the other hand, when the voltage of the specific second sensor connection path 93 with respect to the reference voltage line 68 exceeds the breakdown voltage of the second diode 104, the specific second sensor connection path 93 is electrically connected to the reference voltage line 68 via the second diode 104. The second diode 104 according to this embodiment is a Zener diode. However, as long as the second diode 104 has a suitable breakdown voltage, the second diode 104 is not limited to the Zener diode.

[0039] Assume that, in the configuration described above, an unintended continuity between the first temperature sensor 62 and the first relay 42, and an unintended continuity between the second temperature sensor 64 and the second relay 44 occur simultaneously. In this case, at least one of the first sensor connection paths 91 and 92 is electrically connected to the first relay 42, and at least one of the second sensor connection paths 93 and 94 is electrically connected to the second relay 44. As a result, a DC voltage is applied from the battery 38 between the at least one of the first sensor connection paths 91 and 92 and the at least one of the second sensor connection paths 93 and 94 from the DC circuit 40.

[0040] For example, as it is in Fig. 4, assume that an unintentional continuity between the first temperature sensor 62 and the first relay 42 on the side of the one terminal 62a (position C in Fig. 4) of the first temperature sensor 62 occurs, and that an unintentional continuity between the second temperature sensor 64 and the second relay 44 on the side of the one terminal 64a (position A in Fig. 4) of the second temperature sensor 64. In this case, a DC voltage from the battery 38 is applied between the first sensor connection path 91 connected to one terminal 62a of the first temperature sensor 62 and the second sensor connection path 93 connected to one terminal 64a of the second temperature sensor 64. Accordingly, a voltage exceeding the breakdown voltage is applied to the second diode 104 in the reverse direction. Therefore, the second sensor connection path 93 is electrically connected to the reference voltage line 68 via the second diode 104. When the second sensor connection path 93 is electrically connected to the reference voltage line 68, the potential of the reference voltage line 68 becomes higher than that of the first sensor connection path 91. Therefore, the reference voltage line 68 is electrically connected to the first sensor connection path 91 via the first diode 102.As a result, as shown in . Fig. 4, a short-circuit current SC from the DC circuit 40 flows from the second sensor connection path 93, through the second diode 104, the reference voltage line 68, and the first diode 102, in this order, into the first sensor connection path 91. Since the various elements (e.g., pull-up resistors 82a and 82b) of the sensor input circuit 80 do not exist in the path in which the short-circuit current SC flows, damage to the sensor input circuit 80 is prevented. When the short-circuit current SC flows, the overcurrent protection elements 100 of the first sensor connection path 91 and the second sensor connection path 93 lose conductivity, so that the first sensor connection path 91 and the second sensor connection path 93 are electrically disconnected.Consequently, the positions C and A of the inadvertent passage that occurred at the first temperature sensor 62 and the second temperature sensor 64 are electrically isolated from the sensor input circuit 80.

[0041] Alternatively, as in Fig. 5, assume that an unintentional continuity between the first temperature sensor 62 and the first relay 42 on the side of the other terminal 62b (position D in Fig. 5) of the first temperature sensor 62 occurs, and that an unintentional continuity between the second temperature sensor 64 and the second relay 44 on the side of the one terminal 64a (position A in Fig. 5) of the second temperature sensor 64. In this case, a DC voltage is applied from the battery 38 between the first sensor connection path 92, which is connected to the other terminal 62b of the first temperature sensor 62, and the second sensor connection path 93, which is connected to the one terminal 64a of the second temperature sensor 64. Accordingly, a voltage exceeding the breakdown voltage is applied to the second diode 104 in the reverse direction. Therefore, the second sensor connection path 93 is electrically connected to the reference voltage line 68 via the second diode 104. In contrast, the first sensor connection path 92 is directly connected to the reference voltage line 68 in the sensor input circuit 80. As a result, as shown in Fig. 5, a short-circuit current SC from the DC circuit 40 flows from the second sensor connection path 93, through the second diode 104, and the reference voltage line 68, in this order, into the first sensor connection path 92. Since the various elements of the sensor input circuit 80 also do not exist in the path in which the short-circuit current SC flows, damage to the sensor input circuit 80 is prevented. When the short-circuit current SC flows, the overcurrent protection elements 100 of the first sensor connection path 92 and the second sensor connection path 93 lose conductivity, so that the first sensor connection path 92 and the second sensor connection path 93 are electrically disconnected. Consequently, the positions D and A of the inadvertent passage that occurred at the first temperature sensor 62 and the second temperature sensor 64 are electrically disconnected from the sensor input circuit 80.

[0042] Alternatively, as in Fig. 6, assume that an unintentional continuity between the first temperature sensor 62 and the first relay 42 on the side of the one terminal 62a (position C in Fig. 6) of the first temperature sensor 62 occurs, and that an unintentional continuity between the second temperature sensor 64 and the second relay 40 on the side of the other terminal 64b (position B in Fig. 6) of the second temperature sensor 64. In this case, a DC voltage is applied from the battery 38 between the first sensor connection path 91, which is connected to one terminal 62a of the first temperature sensor 62, and the second sensor connection path 94, which is connected to the other terminal 64b of the second temperature sensor 64. The second sensor connection path 94 is directly connected to the reference voltage line 68 in the sensor input circuit 80. Accordingly, the potential of the reference voltage line 68 becomes higher than that of the first sensor connection path 91, so that the reference voltage line 68 is electrically connected to the first sensor connection path 91 via the first diode 102. As a result, as shown in Fig. 6, a short-circuit current SC from the DC circuit 40 flows from the second sensor connection path 94, through the reference voltage line 68 and the first diode 102, in this order, into the first sensor connection path 91. Since the various elements of the sensor input circuit 80 also do not exist in the path in which this short-circuit current SC flows, damage to the sensor input circuit 80 is prevented. When the short-circuit current SC flows, the overcurrent protection elements 100 of the first sensor connection path 91 and the second sensor connection path 94 lose conductivity, so that the first sensor connection path 91 and the second sensor connection path 94 are electrically disconnected. Consequently, the positions C and D of the unintentional passage that occurred at the first temperature sensor 62 and the second temperature sensor 64 are electrically disconnected from the sensor input circuit 80.

[0043] Alternatively, as in Fig. 7, assume that an unintentional continuity between the first temperature sensor 62 and the first relay 42 on the side of the other terminal 62b (position D in Fig. 7) of the first temperature sensor 62, and that an unintentional continuity between the second temperature sensor 64 and the second relay 44 on the side of the other terminal 64b (position B in Fig. 7) of the second temperature sensor 64. In this case, a DC voltage is applied from the battery 38 between the first sensor connection path 92, which is connected to the other terminal 62b of the first temperature sensor 62, and the second sensor connection path 94, which is connected to the other terminal 64b of the second temperature sensor 64. The first sensor connection path 92 is directly connected to the reference voltage line 68 in the sensor input circuit 80. Likewise, the second sensor connection path 94 is also directly connected to the reference voltage line 68 in the sensor input circuit 80. As a result, as shown in Fig. 7, a short-circuit current SC from the DC circuit 40 flows from the second sensor connection path 94 through the reference voltage line 68 into the first sensor connection path 92. Since various elements of the sensor input circuit 80 in the path in which this short-circuit current SC also do not exist, damage to the sensor input circuit 80 is prevented. When the short-circuit current SC flows, the overcurrent protection elements 100 of the first sensor connection path 92 and the second sensor connection path 94 lose conductivity, so that the first sensor connection path 92 and the second sensor connection path 94 are electrically disconnected. Consequently, the positions D and B of the inadvertent passage that occurred at the first temperature sensor 62 and the second temperature sensor 64 are electrically disconnected from the sensor input circuit 80.Depending on the positions of the unintended passage occurring at the first temperature sensor 62 and the second temperature sensor 64, two or more of the short-circuit currents SC shown in . Fig. 4 to 7, occur simultaneously.

[0044] As described above, according to the protection circuit 90 of this embodiment, when an accidental continuity between the first temperature sensor 62 and the first relay 42 and an accidental continuity between the second temperature sensor 64 and the second relay 44 occur simultaneously, the path in which a short-circuit current SC flows is formed in such a way that the sensor input circuit 80 is not damaged. In the path in which the short-circuit current SC flows, the overcurrent protection elements 100 are provided such that the overcurrent protection elements 100 lose conduction to quickly disconnect the sensor input circuit 80 from the DC circuit 40.

[0045] In the protection circuit 90 described above, only the first sensor connection path 91 of the first sensor connection paths 91 and 92 is connected to the reference voltage line 68 via the first diode 102. However, if the normal voltage of the other first sensor connection path 92 is higher than the normal voltage of the reference voltage line 68, the other first sensor connection path 92 may also be connected to the reference voltage line 68 via another first diode 102. For example, if the other terminal 62b of the first temperature sensor 62 is connected to the reference voltage line 68 via a resistor or the like in the sensor input circuit 80, the normal voltage of the other first sensor connection path 92 will also be higher than the normal voltage of the reference voltage line 68.Similarly, when the normal voltage of the second sensor connection path 94 connected to the other terminal 64b of the second temperature sensor 64 is higher than the normal voltage of the reference voltage line 68, the second sensor connection path 94 may also be connected to the reference voltage line 68 via another second diode 104.

[0046] The temperature detection device 60 according to this embodiment is not limited to the use of detecting the temperatures of the first relay 42 and the second relay 44. For example, as shown in Fig. 8 and Fig. 9, by disposing the first temperature sensor 62 and / or the second temperature sensor 64 so as to be adjacent to the battery 38, it is possible to detect the temperature of the secondary battery cells 38c constituting the battery 38 or the temperature of a conductive part connected to the secondary battery cells 38. Furthermore, the temperature detection device 60 according to this embodiment is not limited to the hybrid vehicle 10 and is also applicable to a battery vehicle that does not have the engine 22 and to a fuel cell vehicle that has a fuel cell as a DC power supply. Furthermore, the temperature detection device 60 according to this embodiment is not necessarily limited to one mounted on a vehicle.

[0047] The temperature detecting device 60 according to this embodiment can be widely applied to detecting temperatures of two parts having a potential difference in various DC circuits.

[0048] The temperature sensing device 60 may include three or more temperature sensors to respectively detect the temperatures of three or more parts of the DC circuit 40. Fig. 10 shows a modification of the temperature detection device 60, wherein a temperature detection device 60 is shown to which a third temperature sensor 65 is added. In the Fig.In the temperature sensing device 60 shown in Figure 10, a first temperature sensor 62 is disposed adjacent to a first part 39a in a battery 38, a second temperature sensor 64 is disposed adjacent to a second part 39b in the battery 38, and a third temperature sensor 65 is disposed adjacent to a third part 39c in the battery 38. A plurality of secondary battery cells 38c are disposed between the first part 39a and the second part 39b such that the second part 39b has a higher potential than the first part 39a. A plurality of secondary battery cells 38c are also disposed between the second part 39b and the third part 39c such that the third part 39c has a higher potential than the second part 39b.

[0049] The configurations of a sensor input circuit 80 and a protection circuit 90 for the third temperature sensor 65 are the same as the configurations of the sensor input circuit 80 and the protection circuit 90 for the second temperature sensor 64. That is, in the sensor input circuit 80, one terminal 65a of the third temperature sensor 65 is connected to a power supply voltage line 66 via a pull-up resistor 82c and is connected to a reference voltage line 68 via two capacitors 84c and 88c. Furthermore, the sensor input circuit 80 connects one terminal 65a of the third temperature sensor 65 to a monitoring circuit 70 via a resistor 86c. In contrast, the other terminal 65b of the third temperature sensor 65 is directly connected to the reference voltage line 68 via no resistor, capacitor, or the like in the sensor input circuit 80.The protection circuit 90 has a plurality of third sensor connection paths 95 and 96. The third sensor connection paths 95 and 96 each have at least one overcurrent protection element 100 and connect the terminals 65a and 65b of the third temperature sensor 65 to the sensor input circuit 80, respectively.

[0050] Of the third sensor connection paths 95 and 96, the third sensor connection path 95, whose normal voltage differs from the reference voltage line 68, is connected to the reference voltage line 68 via a third diode 106 in a section between the overcurrent protection element 100 and the sensor input circuit 80. In this specification, the third sensor connection path 95, whose normal voltage differs from the reference voltage line 68, may be referred to as the specific third sensor connection path 95. The anode of the third diode 106 is connected to the reference voltage line 68. The cathode of the third diode 106 is connected to the specific third sensor connection path 95. The breakdown voltage of the third diode 106 is higher than a maximum value of the normal voltage of the specific third sensor connection path 95, but is lower than a potential difference between the second part 39b and the third part 39c.For example, a Zener diode can be used as the third diode 106.

[0051] According to the configuration described above, even if accidental passages occur between two or more of the three temperature sensors 62, 64, and 65, damage to the sensor input circuit 80 can be prevented by the protection circuit 90. This also applies in a case where the temperature detection device 60 has four or more temperature sensors. In this case, the temperature sensor that measures the temperature of a part with the lowest potential can adopt the same configuration as the first temperature sensor 62 (ie, the configuration using the first diode 102), while the other temperature sensors can adopt the same configuration as the second temperature sensor 64 or the third temperature sensor 65 (ie, the configuration using the second diode 104 or the third diode 106).

[0052] The first relay 42 described according to this embodiment is an example of a first part. The second relay 44 described according to this embodiment is an example of a second part. The battery 38 described according to this embodiment is an example of a DC power supply. The first diode 102 described according to this embodiment is an example of a rectification element. The second diode 104 described according to this embodiment is an example of an overvoltage protection element. The breakdown voltage of the second diode 104 is an example of a predetermined voltage value.

[0053] The technical features of the above-described embodiment are described below. The technical features described below are all independently useful.

[0054] In a temperature sensing device disclosed in this specification, an overvoltage protection element may be a Zener diode. In this case, the anode of the Zener diode may be connected to a reference voltage line, the cathode of the Zener diode may be connected to a specific second sensor connection path, and the breakdown voltage of the Zener diode may be higher than a maximum value of the normal voltage of the specific second sensor connection path, but lower than a potential difference between a first part and a second part. The Zener diode is designed with a relatively precise breakdown voltage. By applying the Zener diode as the overvoltage protection element, the function required for the overvoltage protection element can be appropriately obtained.

[0055] A temperature detection device disclosed in this specification can be applied to a DC circuit having a DC power supply. In this case, a first part, to which a first temperature sensor is disposed adjacent, may be a first relay connected to a negative electrode of the DC power supply, whereas a second part, to which a second temperature sensor is disposed adjacent, may be a second relay connected to a positive electrode of the DC power supply. By detecting the temperatures of the first and second relays through which a relatively large current flows, it is possible to prevent or reduce a failure such as welding of the first and second relays.

[0056] As described above, a protection circuit includes a first sensor connection path 91, which includes a first overcurrent protection element 100 and connects one of the terminals of a first temperature sensor 62 to a sensor input circuit 80; a second sensor connection path 93, which includes a second overcurrent protection element 100 and connects one of the terminals of a second temperature sensor 64 to the sensor input circuit;a rectification element 102 that connects the first sensor connection path, whose normal voltage is higher than a reference voltage line, to the reference voltage line in a section between the first overcurrent protection element and the sensor input circuit, and an overcurrent protection element 104 that connects the second sensor connection path, whose normal voltage is higher than the reference voltage line, to the reference voltage line in a section between the second overcurrent protection element and the sensor input circuit;

Claims

[1] Temperature detection device (60) with: a first temperature sensor (62) arranged adjacent to a first part in a DC circuit (40), a second temperature sensor (64) arranged adjacent to a second part in the DC circuit (40), the second part having a higher potential than the first part, a sensor input circuit (80) connecting a first terminal of the first temperature sensor (62) and a second terminal of the second temperature sensor (64) to a power supply voltage line (66) and connecting a third terminal of the first temperature sensor (62) and a fourth terminal of the second temperature sensor (64) to a reference voltage line (68), and a protection circuit (90) provided between the first and second temperature sensors (62, 64) and the sensor input circuit (80), wherein the protective circuit (90) comprises: a first sensor connection path (91) having a first overcurrent protection element (100) and connecting the first terminal of the first temperature sensor (62) to the power supply voltage line (66) of the sensor input circuit (80), a second sensor connection path (93) having a second overcurrent protection element (100) and connecting the second terminal of the second temperature sensor (64) to the power supply voltage line (66) of the sensor input circuit (80), a third sensor connection path (92) having a third overcurrent protection element (100) and connecting the third terminal of the first temperature sensor (62) to the reference voltage line (68) of the sensor input circuit (80), a fourth sensor connection path (94) having a fourth overcurrent protection element (100) and connecting the fourth terminal of the second temperature sensor (64) to the reference voltage line (68) of the sensor input circuit (80), a rectification element (102) connecting the first sensor connection path (91) to the reference voltage line (68) in a section between the first overcurrent protection element (100) and the sensor input circuit (80), wherein the first sensor connection path (91) has a normal voltage higher than the reference voltage line (68), and an overvoltage protection element (104) connecting the second sensor connection path (93) to the reference voltage line (68) in a section between the second overcurrent protection element (100) and the sensor input circuit (80), wherein the second sensor connection path (93) has a normal voltage that is higher than the reference voltage line (68), wherein the first overcurrent protection element (100), the second overcurrent protection element (100), the third overcurrent protection element (100) and the fourth overcurrent protection element (100) are each an element that loses conductivity when a current exceeding a predetermined current value flows therethrough, the rectification element (102) prevents a flow of current from the first sensor connection path (91) to the reference voltage line (68) and allows a flow of current from the reference voltage line (68) to the first sensor connection path (91), the overvoltage protection element (104) electrically connects the second sensor connection path (93) to the reference voltage line (68) when a voltage of the second sensor connection path (93) with respect to the reference voltage line (68) exceeds a predetermined voltage value, and the predetermined voltage value is higher than a maximum value of the normal voltage of the second sensor connection path (93) and lower than a potential difference between the first part and the second part, wherein the rectification element (102) is a diode, the overvoltage protection element (104) is a Zener diode, an anode of the Zener diode is connected to the reference voltage line (68), a cathode of the Zener diode is connected to the second sensor connection path (93), and a breakdown voltage of the Zener diode is equal to the predetermined voltage value. [2] Temperature detection device (60) according to claim 1, wherein the DC circuit (40) comprises a DC power supply (38), the first part is a first relay (42) connected to a negative electrode of the DC power supply (38), and the second part is a second relay (44) connected to a positive electrode of the DC power supply (38). [3] Temperature detection device (60) according to claim 1, wherein the DC circuit (40) comprises a DC power supply (38), and the first part is the DC power supply (38). [4] Temperature detection device (60) according to claim 1, wherein the DC circuit (40) comprises a DC power supply (38), and the second part is the DC power supply (38). [5] Temperature detection device (60) according to claim 1, wherein the DC circuit (40) comprises a DC power supply (38) in which a plurality of power supplies (38c) are connected in series, the first part is a negative side of the DC power supply (38), and the second part is a positive side of the DC power supply (38).

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