Limp control circuit, limp control system and automobile

Abstract

The embodiment of the present invention provides a limp home control circuit, a limp home control system and a car, and relates to the field of electronic control technology. The limp home control circuit includes: a control unit, a limp home backup unit and a drive unit; the control unit is used to send a first enable signal to the drive unit in response to a first activation signal; the drive unit is used to output a drive signal to drive a load and a limp home backup unit after receiving the first enable signal; the limp home backup unit is used to output a second enable signal to the drive unit after receiving the drive signal to keep the drive unit outputting the drive signal. The present invention activates the limp home backup unit to output an enable signal to react to the drive unit with the drive signal output by the drive unit, so that the drive unit forms an output self-locking state. When the control unit fails, the drive unit can still maintain output, thereby realizing the limp home function of the car. At the same time, compared with the prior art, the present invention has a simple structure and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic control, and in particular to a limp home control circuit, a limp home control system and a vehicle. Background Art

[0002] The safety of a car in driving is extremely important. Among them, the control of headlights, brake lights, wipers, ignition power supply network and other controls in the body control are all related to driving safety under different working conditions. They are generally defined as ASILB level in functional safety requirements, so a hardware backup control design with limp home function is required. At present, the use of SBC chips with limp home output unit Fail-Safe is the mainstream solution on the market. Among them, SBC chips, also known as system basis chips (System Basis Chip), are comprehensive functional chips that integrate power supply units, CAN / LIN communication transceivers, watchdog units and limp home output units. The watchdog unit of the SBC chip monitors the state of the microcontroller. When the microcontroller hardware or software fails and the dog is missing, the SBC chip enters the Fail-Safe mode and outputs a Safe hardware signal. Combined with the backup output hardware circuit, the pure hardware control method is used to maintain the control effect of the functional output to meet the ASILB functional safety level requirements. However, the use of SBC chips to achieve limp home function has the problem of high chip prices and extra costs. Summary of the invention

[0003] The purpose of the embodiments of the present invention is to provide a limp home control circuit, a limp home control system and a vehicle, so as to solve the problem of high cost of the existing limp home control circuit.

[0004] In order to achieve the above object, in a first aspect of the present invention, a limp home control circuit is provided, comprising:

[0005] control unit, limp home backup unit and drive unit;

[0006] The control unit is used for sending a first enabling signal to the driving unit in response to the first activation signal;

[0007] The driving unit is used for outputting a driving signal to drive the load and the limp home backup unit after receiving the first enabling signal;

[0008] The limp home backup unit is used for outputting a second enable signal to the driving unit after receiving the driving signal to keep the driving unit outputting the driving signal.

[0009] Optionally, the limp control circuit further comprises:

[0010] The limp home shutdown unit is used to control the limp home backup unit to interrupt the output of the second enable signal after receiving the third enable signal sent by the control unit.

[0011] Optionally, the limp control circuit further comprises:

[0012] The load status monitoring unit is used to feed back the current operating status of the load to the control unit after the control unit sends the third enable signal. If the current operating status of the load is a stopped operating status, the control unit stops sending the third enable signal.

[0013] Optionally, the limp control circuit further comprises:

[0014] an input unit, configured to send the first activation signal to the control unit; and

[0015] A second activation signal is sent to the limp home backup unit to cause the limp home backup unit to stop outputting the second enable signal.

[0016] Optionally, the limp home backup unit comprises:

[0017] A first switching element, a second switching element and a third switching element;

[0018] The control end of the first switch element is connected to the output end of the drive unit as the receiving end of the drive signal, the first end of the first switch element is connected to the first reference signal, and the second end of the first switch element is connected to the control end of the second switch element;

[0019] The first end of the second switch element is connected to the control end of the third switch element, the second end of the second switch element is grounded, the first end of the third switch element is connected to the second reference signal, and the second end of the third switch element is connected to the input end of the driving unit as the output end of the second enable signal.

[0020] Optionally, the driving unit is a low-end driving chip, the first switch element and the third switch element are PNP switch elements, and the second switch element is an NPN switch element.

[0021] Optionally, the limp close unit comprises:

[0022] A fourth switch element, wherein the control end of the fourth switch element is connected to the control unit as the receiving end of the third enable signal, the first end of the fourth switch element is connected to the second end of the first switch element and the control end of the second switch element, and the second end of the fourth switch element is grounded.

[0023] Optionally, the input unit includes:

[0024] Reset switch;

[0025] The first end of the reset switch is grounded, the second end of the reset switch is connected to the control unit as a first activation signal output end, and the second end of the reset switch is connected to the second end of the first switch element and the control end of the second switch element as a second activation signal output end.

[0026] In a second aspect of the present invention, there is provided a limp control system, comprising:

[0027] The limp home control circuit described above;

[0028] load control circuit; and

[0029] load;

[0030] The limp home control circuit outputs the driving signal to control the load control circuit to conduct a power supply loop between the load and a power source.

[0031] In a third aspect of the present invention, a vehicle is provided, comprising the above-mentioned limp home control system.

[0032] The above technical solution of the present invention provides an enable signal through the control unit to control the drive unit to output the drive signal to drive the load to work, and at the same time activates the limp home backup unit to output an enable signal to react to the drive unit with the drive signal output by the drive unit, so that the drive unit forms an output self-locking state. When the control unit fails, the drive unit can still maintain output, thereby realizing the limp home function of the car. At the same time, compared with the prior art, the present invention has a simple structure and low cost.

[0033] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0035] Figure 1 is a structural schematic diagram of a limp home control circuit provided in a preferred embodiment of the present invention;

[0036] Figure 2 4 is a circuit diagram of a limp home control circuit provided in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0037] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0038] like Figure 1 As shown, in a first aspect of the present invention, a limp home control circuit is provided, comprising:

[0039] A control unit, a limp home backup unit and a drive unit; the control unit is used to send a first enable signal to the drive unit in response to a first activation signal; the drive unit is used to output a drive signal to drive the load and the limp home backup unit after receiving the first enable signal; the limp home backup unit is used to output a second enable signal to the drive unit after receiving the drive signal to keep the drive unit outputting the drive signal.

[0040] In this way, this embodiment provides an enable signal through the control unit to control the drive unit to output a drive signal to drive the load to work, and at the same time, the drive signal output by the drive unit activates the limp home backup unit to output an enable signal to react to the drive unit, so that the drive unit forms an output self-locking state. When the control unit fails, the drive unit can still maintain output, thereby realizing the limp home function of the car. At the same time, compared with the existing technology, it has the advantages of simple structure and low cost.

[0041] Specifically, the limp home function (LimpHome) is a function for backing up the output. When the main control unit in the automotive electronic controller fails and fails to operate, the backup control circuit is immediately started to control the controlled unit to maintain the output state and achieve the strategy of effective functional safety goals. This implementation method takes the load unit as an ignition power network as an example. The ignition power network is the power network connected after the car is started. It is used to supply power to some electronic controllers after starting and during driving. The network is powered off after the car is turned off to reduce battery power consumption. In this embodiment, the control unit is a single-chip microcomputer, and the driving unit is a driving chip. After receiving the first activation signal input from the outside, the single-chip microcomputer outputs a first enable signal to the driving chip through an I / O terminal to activate the driving chip. The driving signal output by the driving chip is used to drive the load unit on the one hand. For example, the driving signal controls the peripheral circuit so that the normally open contact of the relay arranged between the ignition power supply network and the vehicle-mounted electrical equipment is closed, and the power supply circuit between the ignition power supply network and the battery is turned on. On the other hand, the driving signal is input into the limp home backup unit to drive the limp home backup unit to input a second enable signal to the driving unit. For example, the limp home backup unit controls the driving unit to access a reference signal as the second enable signal of the driving unit through a switch element. The reference signal can be a 5V voltage signal. In this way, when the single-chip microcomputer fails and cannot output the first enable signal, the limp home backup unit drives the driving unit through the reference signal to maintain the output of the driving unit, thereby maintaining the power supply circuit between the ignition power supply network and the battery to ensure that the load can operate normally.

[0042] In order to avoid the situation that after the vehicle triggers the limp home function, even if the single-chip microcomputer stops outputting the first enable signal, the output of the drive unit cannot be turned off, thereby causing the vehicle battery to continue to consume power, the limp home control circuit also includes: a limp home shutdown unit, which is used to control the limp home backup unit to interrupt the output of the second enable signal after receiving the third enable signal sent by the control unit. When the limp home function needs to be turned off, the single-chip microcomputer outputs the third enable signal to the limp home shutdown unit through another I / O port to trigger the limp home unit to interrupt the limp home backup unit from outputting the second enable signal. For example, the limp home shutdown unit controls the switch element of the limp home backup unit to disconnect the path between the reference signal and the drive unit by changing the voltage signal at the control end of the switch element, thereby turning off the output of the drive unit.

[0043] Preferably, the limp control circuit further comprises: a load state monitoring unit, which is used to feed back the current operating state of the load to the control unit after the control unit sends the third enable signal. If the current operating state of the load is a stopped operating state, the control unit stops sending the third enable signal. The load state monitoring unit can determine the operating state of the ignition power supply network by detecting the voltage signal at the detection point between the battery and the ignition power supply network. After the single-chip microcomputer sends the third enable signal to the limp shutoff unit, the voltage signal at the detection point is detected in real time. If it is determined by the voltage signal that the battery is disconnected from the ignition power supply network, the single-chip microcomputer stops sending the third enable signal to the limp shutoff unit.

[0044] Preferably, the limp home control circuit further comprises: an input unit for sending a first activation signal to the control unit; and sending a second activation signal to the limp home backup unit so that the limp home backup unit interrupts outputting the second enable signal. The input unit can be implemented by a physical switch button or a virtual control of a human-computer interaction interface.

[0045] like Figure 2 As shown, in this embodiment, the limp home backup unit includes: a first switch element Q1, a second switch element Q2 and a third switch element Q3; wherein the driver chip U2 is a low-end driver chip (LSD), the first switch element Q1 and the third switch element Q3 are PNP type switch elements, such as PNP type transistors, and the second switch element Q2 is an NPN type switch element, such as an NPN type transistor. The base of the first switch element Q1 is connected to the output end of the driving chip U2 through the first resistor to serve as the receiving end of the driving signal. At the same time, in order to ensure that the first switch element Q1 is reliably turned off, a second resistor is also connected in series between the emitter and the base of the first switch element Q1; the emitter of the first switch element Q1 is connected to the first reference signal, wherein the first reference signal is a 5V voltage signal, the collector of the first switch element Q1 is connected to the base of the second switch element Q2 through the third resistor and the fourth resistor connected in series in sequence, the emitter of the second switch element Q2 is grounded and the base and emitter of the second switch element Q2 are connected through the fifth resistor; the collector of the second switch element Q2 is connected to the base of the third switch element Q3 through the sixth resistor, the emitter of the third switch element Q3 is connected to the second reference signal and the emitter of the third switch element Q3 is connected to its base through the seventh resistor, wherein the second reference signal is a 5V voltage signal, and the collector of the third switch element Q3 is connected to the input end of the driving unit as the output end of the second enable signal.

[0046] The limp-off unit includes: a fourth switch element Q4, which is an NPN-type transistor, wherein the base of the fourth switch element Q4 serves as a receiving end of a third enable signal, and is connected to the output end OUT1 of the control unit through an eighth resistor, the collector end of the fourth switch element Q4 is connected between the third resistor and the fourth resistor, so as to be respectively connected to the collector of the first switch element Q1 and the base of the second switch element Q2, the emitter of the fourth switch element Q4 is grounded, and the emitter and base of the fourth switch element Q4 are connected through a ninth resistor.

[0047] In this embodiment, the input unit includes: a reset switch B1 that resets after being pressed; the first end of the reset switch B1 is grounded, the second end of the reset switch B1 is connected to the input end IN1 of the control unit as a first activation signal output end, and the second end of the reset switch B1 is connected between the third resistor and the fourth resistor as a second activation signal output end, thereby being connected to the collector of the first switching element Q1, the base of the second switching element Q2 and the collector of the fourth switching element Q4.

[0048] When the reset switch B1 is pressed, the input terminal IN1 of the single-chip microcomputer U1 detects the action of the reset switch B1 being pressed, and then outputs a first enable signal to the input terminal IN of the driver chip U2 through the output terminal OUT2 of the single-chip microcomputer U1 to activate the driver chip U2. When the output terminal OUT of the driver chip U2 outputs a drive signal, the relay R1 is triggered to act. For example, the drive signal is a grounding effective signal of the relay R1, so that the relay R1 is connected to the ground to form a loop, the coil of the relay R1 is energized, and its normally open contact is closed, thereby connecting the ignition power supply network IGN1 and the 12V voltage provided by the battery, so that the ignition power supply network IGN1 can supply power to vehicle loads such as wipers, turn signals, etc., wherein the control circuit of the driver chip to the relay is a conventional technical means, which will not be repeated here. At the same time, the driving signal output from the output terminal OUT of the driving chip U2 acts on the base of the first switching element Q1, causing the emitter and collector of the first switching element Q1 to be turned on, so that the 5V voltage signal acts on the base of the second switching element Q2 to trigger the emitter and collector of the second switching element Q2 to be turned on. Since the emitter of the second switching element Q2 is grounded, the base voltage of the third switching element Q3 is pulled down, causing the emitter and collector of the third switching element Q3 to be turned on, so that the 5V voltage signal connected to the emitter of the third switching element Q3 acts on the input terminal IN of the driving chip U2, thereby realizing the output latch of the driving chip U2.

[0049] When the relay R1 needs to stop working, the single-chip computer U1 turns off the output terminal OUT2 to stop outputting the first enable signal to the input terminal IN of the driver chip U2. At this time, the 5V voltage signal connected to the emitter of the third switch element Q3 at the input terminal IN of the driver chip U2 is used as the second enable signal. After the single-chip computer U1U1 turns off the output of the output terminal OUT2, it activates its output terminal OUT1 to output the third enable signal to control the emitter and collector of the fourth switch element Q4 to be turned on. At this time, the base of the second switch element Q2 is short-circuited to the ground, and the base voltage of the second switch element Q2 is pulled down, causing the second switch element Q4 to be turned on. The emitter and collector of the switching element Q2 are disconnected, and then the collector and emitter of the third switching element Q3 are disconnected. At this time, there is no enable signal input to the input terminal IN of the driving chip U2, and its output terminal OUT stops outputting the driving signal, causing the power supply circuit of the relay R1 to be disconnected, the relay R1 coil to lose power, its normally open contact to be disconnected, and the path between the ignition power network IGN1 and the battery to be disconnected. At this time, the voltage signal of the ignition power network IGN1 is fed back to the input terminal IN2 of the single-chip microcomputer U1. When the single-chip microcomputer U1 determines that the ignition power network IGN1 is powered off, the output of the output terminal OUT1 is turned off.

[0050] When the driver chip U2 is in the output latch state, if the single-chip microcomputer U1 has a software or hardware failure that causes its function to fail, after the output terminal OUT of the single-chip microcomputer U1 stops outputting, the driver chip U2 maintains outputting through the 5V voltage signal connected to the emitter of the third switch element Q3, so that the relay R1 remains activated and the ignition power supply network IGN1 remains powered to ensure that other loads can operate normally. At this time, if the ignition power supply network IGN1 needs to be disconnected from the battery, the reset switch B1 can be pressed. At this time, the base of the second switch element Q2 is short-circuited to the ground, and the second The base voltage of the switching element Q2 is pulled down, causing the emitter and collector of the second switching element Q2 to be disconnected, and then the collector and emitter of the third switching element Q3 are disconnected. At this time, there is no enable signal input to the input terminal IN of the driving chip U2, and its output terminal OUT stops outputting the driving signal, causing the power supply circuit of the relay R1 to be disconnected, the relay R1 coil to lose power, its normally open contact to be disconnected, and the path between the ignition power network IGN1 and the battery to be disconnected. At the same time, the emitter and collector of the first switching element Q1 are disconnected, and the output latch state of the driving chip U2 is completely closed.

[0051] In a second aspect of the present invention, a limp home control system is provided, comprising: the above-mentioned limp home control circuit; a load control circuit; and a load; the limp home control circuit outputs a drive signal to control the load control circuit to conduct a power supply circuit between the load and a power source.

[0052] In a third aspect of the present invention, a vehicle is provided, comprising the above-mentioned limp home control system.

[0053] To sum up, in this embodiment, the control unit provides an enable signal to control the drive unit to output a drive signal to drive the load to work, and at the same time, the drive signal output by the drive unit activates the limp home backup unit to output an enable signal to react to the drive unit, so that the drive unit forms an output self-locking state. When the control unit fails, the drive unit can still maintain output, thereby realizing the limp home function of the car. At the same time, compared with the prior art, the present invention has a simple structure and can effectively reduce costs.

[0054] The optional embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the technical concept of the embodiments of the present invention, a variety of simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0055] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0056] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A limp home control circuit, characterized in that: include: control unit, limp home backup unit and drive unit; The control unit is used for sending a first enabling signal to the driving unit in response to the first activation signal; The driving unit is used for outputting a driving signal to drive the load and the limp home backup unit after receiving the first enabling signal; The limp home backup unit is used for outputting a second enable signal to the drive unit after receiving the drive signal to keep the drive unit outputting the drive signal; The limp control circuit further comprises: a limp home shutdown unit, configured to control the limp home backup unit to interrupt output of the second enable signal after receiving the third enable signal sent by the control unit; The limp control circuit further comprises: an input unit, configured to send the first activation signal to the control unit; and sending a second activation signal to the limp home backup unit so that the limp home backup unit stops outputting the second enable signal; The limp home backup unit comprises: A first switching element, a second switching element and a third switching element; The control end of the first switch element is connected to the output end of the drive unit as the receiving end of the drive signal, the first end of the first switch element is connected to the first reference signal, and the second end of the first switch element is connected to the control end of the second switch element; The first end of the second switch element is connected to the control end of the third switch element, the second end of the second switch element is grounded, the first end of the third switch element is connected to the second reference signal, and the second end of the third switch element is connected to the input end of the driving unit as the output end of the second enable signal; The limp close unit comprises: a fourth switch element, wherein a control end of the fourth switch element is connected to the control unit as a receiving end of the third enable signal, a first end of the fourth switch element is connected to the second end of the first switch element and the control end of the second switch element, and a second end of the fourth switch element is grounded; The input unit comprises: Reset switch; The first end of the reset switch is grounded, the second end of the reset switch is connected to the control unit as a first activation signal output end, and the second end of the reset switch is connected to the second end of the first switch element and the control end of the second switch element as a second activation signal output end.

2. The limp home control circuit according to claim 1, characterized in that: The limp control circuit further comprises: The load status monitoring unit is used to feed back the current operating status of the load to the control unit after the control unit sends the third enable signal. If the current operating status of the load is a stopped operating status, the control unit stops sending the third enable signal.

3. The limp home control circuit according to claim 1, characterized in that: The driving unit is a low-end driving chip, the first switch element and the third switch element are PNP switch elements, and the second switch element is an NPN switch element.

4. A limp control system, characterized in that: include: The limp home control circuit according to any one of claims 1 to 3; load control circuit; and load; The limp home control circuit outputs the driving signal to control the load control circuit to conduct a power supply loop between the load and a power source.

5. A car, characterized in that: Includes the limp control system as claimed in claim 4.

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