Electronic control device

Abstract

To provide an electronic control device in which noise is appropriately suppressed by load while suppressing increase in current consumption.SOLUTION: The electronic control device comprises: a control wiring substrate with signal ground; a housing as frame ground; one or more ground circuits including a ground side connection conductor connected to the frame ground and a load connected between the ground side connection conductor and the signal ground; a monitor connection conductor connected to the frame ground; a connection state detection circuit including a monitor circuit and a switching circuit connected between the monitor connection conductor and a power source and a control circuit. Each ground side connection conductor is a conductive elastic body or a conductive non-elastic body. Each load is resistive load, capacitive load or inductive load. The control circuit determines, on the basis of waveforms detected by the monitor circuit, a state of connection between the frame ground, the ground side connection conductor, the load and the signal ground and a state of connection between the frame ground, the monitor connection conductor and the connection state detection circuit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electronic control device. [Background technology]

[0002] An electronic control device is provided with a control wiring board on which a main circuit such as a control circuit is formed. To suppress radiation of high-frequency noise generated from the control wiring board, the signal ground of the control wiring board is sometimes connected to a frame ground housing that houses the control wiring board, and the housing is used as an electromagnetic shield. When such an electronic control device is installed in a vehicle, the electrical contact between the signal ground and the frame ground may deteriorate due to vehicle vibrations, etc. If the connection between the signal ground and the frame ground deteriorates and becomes insufficient, the desired effect in terms of noise resistance cannot be achieved. Therefore, a configuration for monitoring the connection status between the signal ground and the frame ground has been disclosed (see, for example, Patent Document 1).

[0003] In the connection status detection circuit configuration disclosed in Patent Document 1, a voltage is applied to a detection pattern formed on a printed circuit board, and the electrical connection status between the printed circuit board and the shielding material is detected based on the signal level of the signal detection port. This configuration makes it possible to detect gaps that occur between the shielding material and the printed circuit board. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-54388 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned Patent Document 1, gaps that occur between the shielding material and the printed circuit board can be detected by applying a voltage to the detection pattern. However, because there is no control unit that applies a voltage to the detection pattern at the appropriate timing, there is a problem that the connection status between the signal ground and the frame ground cannot be monitored at the appropriate timing, which may increase current consumption.

[0006] Furthermore, in the disclosed configuration, the load connected to the connection state detection circuit is a resistor, so there is a problem in that the effect of suppressing noise by the load cannot be obtained depending on the target noise.

[0007] Therefore, an object of the present disclosure is to provide an electronic control device that appropriately suppresses noise due to a load while suppressing an increase in current consumption. [Means for solving the problem]

[0008] The electronic control device of the present disclosure comprises: a control wiring board having a main circuit and a signal ground connected to the main circuit; a conductive frame ground and a housing accommodating the control wiring board; one or more ground circuits having a ground-side connecting conductor connected to the frame ground and a load connected in series between the ground-side connecting conductor and the signal ground; a monitor connecting conductor connected to the frame ground; a connection status detection circuit having a current or voltage monitor circuit and a switch circuit connected in series between the monitor connecting conductor and a power source; and a control circuit for turning the switch circuit on and off, wherein each ground-side connecting conductor is a conductive elastic body pressed against and connected to the frame ground or a conductive non-elastic body connected to the frame ground, and each load is a resistive load, a capacitive load, or an inductive load, and the control circuit determines the connection status between the frame ground, the ground-side connecting conductor, the load, and the signal ground, and the connection status between the frame ground, the monitor connecting conductor, and the connection status detection circuit, based on the current or voltage waveform detected by the monitor circuit when the switch circuit is turned on and off. [Effects of the Invention]

[0009] According to the electronic control device disclosed herein, the electronic control device includes a control wiring board having a signal ground, a housing serving as a frame ground, one or more ground circuits each having a ground-side connecting conductor connected to the frame ground and a load connected between the ground-side connecting conductor and the signal ground, a monitor connecting conductor connected to the frame ground, a monitor circuit and a switch circuit connected between the monitor connecting conductor and a power supply, and a connection status detection circuit including a control circuit, wherein each load is a resistive load, a capacitive load, or an inductive load, and the control circuit has a control circuit that turns on and off the switch circuit to determine the connection status between the frame ground, the ground-side connecting conductor, the load, and the signal ground, and the connection status between the frame ground, the monitor connecting conductor, and the connection status detection circuit based on the current or voltage waveform detected by the monitor circuit when the switch circuit is turned on and off, thereby suppressing an increase in current consumption flowing through the connection status detection circuit. Furthermore, the resistive load, the capacitive load, and the inductive load can be selected depending on the effect of the target noise and the frequency band of the noise that needs to be reduced, thereby allowing the selected load to appropriately suppress noise. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view that schematically illustrates an outline of an electronic control device according to a first embodiment. [Figure 2] 1 is an exploded cross-sectional view schematically illustrating an electronic control device according to a first embodiment. [Figure 3] 4 is a cross-sectional view that schematically shows an outline of another electronic control device according to the first embodiment. FIG. [Figure 4] 4 is a cross-sectional view schematically illustrating an outline of another electronic control device according to the first embodiment. FIG. [Figure 5] 3 is a diagram illustrating an example of a circuit for detecting a connection state of the electronic control device according to the first embodiment. FIG. [Figure 6] 4 is another diagram showing an example of a circuit for detecting a connection state of the electronic control device according to the first embodiment. FIG. [Figure 7]4 is a diagram showing an example of waveforms when detecting the connection state of the electronic control device according to the first embodiment. FIG. [Figure 8] 3 is a diagram illustrating an example of a circuit for detecting a connection state of the electronic control device according to the first embodiment. FIG. [Figure 9] 4 is another diagram showing an example of a circuit for detecting a connection state of the electronic control device according to the first embodiment. FIG. [Figure 10] 4 is a diagram showing an example of waveforms when detecting the connection state of the electronic control device according to the first embodiment. FIG. [Figure 11] 3 is a diagram illustrating an example of a circuit for detecting a connection state of the electronic control device according to the first embodiment. FIG. [Figure 12] 4 is another diagram showing an example of a circuit for detecting a connection state of the electronic control device according to the first embodiment. FIG. [Figure 13] 4 is a diagram showing an example of waveforms when detecting the connection state of the electronic control device according to the first embodiment. FIG. [Figure 14] FIG. 10 is a cross-sectional view that schematically illustrates an electronic control device according to a second embodiment. [Figure 15] FIG. 10 is a cross-sectional view that schematically shows an outline of an electronic control device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an electronic control device according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the same or equivalent members and parts in each drawing will be denoted by the same reference numerals.

[0012] Embodiment 1 FIG. 1 is a cross-sectional view showing an outline of an electronic control device 1 according to a first embodiment; FIG. 2 is an exploded cross-sectional view showing an outline of the electronic control device 1 with a fixing screw 15 removed; FIGS. 3 and 4 are cross-sectional views showing an outline of another electronic control device 1 according to the first embodiment; FIGS. 5, 8, and 11 are diagrams showing an example of a circuit for detecting the connection state of the electronic control device 1, showing a normal connection state; FIGS. 6, 9, and 12 are other diagrams showing an example of a circuit for detecting the connection state of the electronic control device 1, showing an abnormal connection state; and FIGS. 7, 10, and 13 are diagrams showing examples of waveforms when the connection state of the electronic control device 1 is detected. The electronic control device 1 is, for example, a control device incorporating an image processing circuit as the main circuit 2a. The electronic control device 1 is, for example, a device mounted on a vehicle for use.

[0013] <Electronic control device 1> As shown in FIG. 1, the electronic control device 1 includes a control wiring board 2 having a main circuit 2a and a signal ground 20 connected to the main circuit 2a, and a housing 3 that houses the control wiring board 2. In this embodiment, as shown in FIG. 2, the housing 3 is composed of a first housing 3a and a second housing 3b. The control wiring board 2 is sandwiched and fixed between the first housing 3a and the second housing 3b. Fixing screws 15 secure the first housing 3a, the second housing 3b, and the control wiring board 2. The housing 3 is made of a conductive metal such as aluminum. The material of the housing 3 is not limited to metal and may be a conductive resin. The control wiring board 2 is, for example, a printed circuit board. The main circuit 2a is composed of multiple electronic components (not shown) mounted on the control wiring board 2. The signal ground 20 connected to the main circuit 2a is the reference potential of the main circuit 2a.

[0014] As shown in Fig. 1, the electronic control device 1 includes one or more ground circuits 4, a monitor connection conductor 8 connected to the frame ground 30, and a connection status detection circuit 10 as circuit sections that detect the connection status between the signal ground 20 and the frame ground 30 of the electronic control device 1. By electrically connecting the signal ground 20 and the frame ground 30, the electromagnetic shielding resistance of the electronic control device 1 can be improved. If the signal ground 20 and the frame ground 30 are not electrically connected, the electromagnetic shielding resistance of the electronic control device 1 will deteriorate. Therefore, by detecting the connection status between the signal ground 20 and the frame ground 30, it is possible to check whether the electromagnetic shielding resistance is good or bad.

[0015] <Grounding circuit 4> The ground circuit 4 includes a ground-side connecting conductor connected to the frame ground 30 and a load 7 connected in series between the ground-side connecting conductor and the signal ground 20. In this embodiment, the electronic control device 1 includes multiple ground circuits 4. The multiple ground circuits 4 include a first ground circuit 4a, a second ground circuit 4b, a third ground circuit 4c, and a fourth ground circuit 4d. Each ground-side connecting conductor is a conductive elastic body 5 pressed against and connected to the frame ground 30, or a conductive non-elastic body 6 connected to the frame ground 30. The conductive elastic body 5 is made of, for example, conductive rubber to which a conductive substance is added. The conductive elastic body 5 is not limited to conductive rubber and may be formed of a metal material with elastic spring properties. When the housing 3 and the control wiring board 2 are fixed together, the conductive elastic body 5 elastically deforms between the first housing 3a and a pad 14 provided on the control wiring board 2, electrically connecting the frame ground 30 and the pad 14. The conductive non-elastic body 6 is, for example, a pad provided on the board surface of the control wiring board 2 facing the housing 3. In this embodiment, both the conductive elastic body 5 and the conductive non-elastic body 6 are provided, but this is not limiting, and only one of the conductive elastic body 5 and the conductive non-elastic body 6 may be provided. FIG. 3 shows an example of a configuration in which only the conductive elastic body 5 is provided, and FIG. 4 shows an example of a configuration in which only the conductive non-elastic body 6 is provided. The conductive non-elastic body 6 is provided at a position along the outer periphery of the housing 3, such as a position adjacent to the fixing screw 15, so the location where the conductive non-elastic body 6 is provided is somewhat limited. The location where the conductive elastic body 5 is provided is not particularly limited.

[0016] When the electronic control device 1 includes multiple ground circuits 4, multiple loads 7 are provided, as shown in FIG. 1 . Each load 7 is a resistive load 7a, a capacitive load 7b, or an inductive load 7c. In this embodiment, one end of the load 7 is connected to the pad 14 or the conductive inelastic body 6, and the other end of the load 7 is connected to the signal ground 20. The resistive load 7a is, for example, a resistive element mounted on the control wiring board 2. The capacitive load 7b is, for example, a capacitor element mounted on the control wiring board 2. The inductive load 7c is, for example, an inductive element mounted on the control wiring board 2. In this embodiment, the first ground circuit 4a has the resistive load 7a as the load 7, the second ground circuit 4b has the capacitive load 7b as the load 7, the third ground circuit 4c has the inductive load 7c as the load 7, and the fourth ground circuit 4d has the capacitive load 7d as the load 7. The configuration of the loads 7 provided in the ground circuits 4 is not limited to this. 3, only a capacitive load 7b is provided as the load 7, and in the configuration shown in Fig. 4, only an inductive load 7c is provided as the load 7. The selection of the load 7 is not limited to this, and other configurations may be used, such as a configuration including only a resistive load 7a, or a configuration including both a resistive load 7a and a capacitive load 7b.

[0017] <Connection status detection circuit 10> As shown in FIG. 1 , the connection status detection circuit 10 includes a current or voltage monitor circuit 11 and a switch circuit 12 connected in series between the monitor connecting conductor 8 and the power supply 9, and a control circuit 13 that turns the switch circuit 12 on and off. The connection status detection circuit 10 is the area surrounded by a dashed line in FIG. 1 . The monitor connecting conductor 8 is, for example, a conductive elastic body that is pressed against the frame ground 30 to connect it, and is made of the same material as the conductive elastic body 5. The control circuit 13 determines the connection status between the frame ground 30, the ground-side connecting conductor, the load 7, and the signal ground 20, as well as the connection status between the frame ground 30, the monitor connecting conductor 8, and the connection status detection circuit 10, based on the current or voltage waveform detected by the monitor circuit 11 when the switch circuit 12 is turned on and off. The details of determining the connection status will be described later.

[0018] As shown in FIG. 5, the switch circuit 12 is, for example, a transistor that applies a voltage to the monitor circuit 11 based on a signal from the control circuit 13. The monitor circuit 11 has, for example, a resistor as a part that monitors the current or voltage. By configuring the switch circuit 12 in this way, including the control circuit 13 that turns on and off, it is possible to suppress an increase in the current consumption flowing through the connection status detection circuit 10. In particular, by applying a voltage only when the connection status is detected, it is possible to significantly suppress the current consumption and improve energy-saving performance. If the electronic control unit 1 is an on-board device, the connection status is detected when the vehicle is started, for example.

[0019] In this embodiment, the connection state detection circuit 10 is provided on the control wiring board 2. The configuration is not limited to providing the connection state detection circuit 10 on the control wiring board 2. The connection state detection circuit 10 may be provided separately from the control wiring board 2. By providing the connection state detection circuit 10 on the control wiring board 2 together with the main circuit 2a, the electronic control device 1 can be made smaller.

[0020] In this embodiment, the conductive non-elastic body 6 is provided adjacent to the fixing screw 15 that fixes the housing 3 and the control wiring board 2. The configuration is not limited to providing the conductive non-elastic body 6 adjacent to the fixing screw 15. The conductive non-elastic body 6 may also be provided away from the fixing screw 15. By providing the conductive non-elastic body 6 adjacent to the fixing screw 15, it is possible to accurately detect whether the fixing screw 15 has loosened or come off.

[0021] <Connection status determination> The connection state determination will now be described. The connection states determined by the control circuit 13 are continuity in the ground circuit 4, continuity between the frame ground 30 and the monitor connecting conductor 8, and continuity between the monitor connecting conductor 8 and the connection state detection circuit 10. As long as the ground circuit 4 is conductive, there is no problem with the electromagnetic shielding resistance of the electronic control device 1 even if there is a discontinuity between the frame ground 30 and the monitor connecting conductor 8 and between the monitor connecting conductor 8 and the connection state detection circuit 10. However, if there is a discontinuity between these, the control circuit 13 cannot determine the continuity in the ground circuit 4. Therefore, the control circuit 13 also determines the continuity between the frame ground 30 and the monitor connecting conductor 8 and between the monitor connecting conductor 8 and the connection state detection circuit 10.

[0022] When the ground-side connecting conductor is a conductive elastic body 5, the points at which continuity in the ground circuit 4 is judged are: discontinuity due to separation between the conductive elastic body 5 and the frame ground 30; discontinuity due to separation between the conductive elastic body 5 and the pad 14; discontinuity due to deterioration of the conductive elastic body 5, the pad 14, or the load 7; and discontinuity due to deterioration of the wiring between the conductive elastic body 5 and the signal ground 20 via the pad 14 and the load 7. When the ground-side connecting conductor is a conductive non-elastic body 6, the points at which continuity in the ground circuit 4 is judged are: discontinuity due to separation between the conductive non-elastic body 6 and the frame ground 30; discontinuity due to deterioration of the conductive non-elastic body 6 or the load 7; and discontinuity due to deterioration of the wiring between the conductive non-elastic body 6 and the signal ground 20 via the load 7.

[0023] Using Figures 5 to 7, we first explain how to determine the connection state in an example configuration with four ground circuits 4 and a resistive load 7a as the load 7. In Figure 5, SW1 to SW4 represent the conductive elastic body 5, SWm represents the monitor connecting conductor 8, R1 to R4 represent the resistance of the resistive load 7a, Qm represents the transistor of the switch circuit 12, and Rm represents the resistance of the monitor circuit 11. The conductive elastic body 5 is considered a switch, and a non-conductivity due to separation of the conductive elastic body 5 from the frame ground 30, for example, is considered to be an open switch. The combined resistance R0 of the four resistive loads 7a in Figure 5 is expressed as R0 = (R1 × R2 × R3 × R4) / (R1 × R2 × (R3 + R4) + R3 × R4 × (R1 + R2)). In Figure 5, A represents the point at which a voltage is applied to the monitor circuit 11, and v(t) represents the point at which the control circuit 13 monitors the voltage. When +V is applied to the monitor circuit 11 from the power supply 9 (Qm is on), the waveform applied to A is the waveform shown in the upper part of Figure 7. If the connection is normal as shown in Figure 5, the voltage monitored is V(H) = +V × R0 / (Rm + R0), as shown by the waveform shown by the solid line in the lower part of Figure 7. In the waveform shown in the lower part of Figure 7, the horizontal axis is time and the vertical axis is voltage.

[0024] As shown in FIG. 6, when the three conductive elastic bodies 5 shown on the right side are separated from the frame ground 30, SW2 to SW4 are opened. In FIG. 6, the combined resistance R0 is expressed as R0 = R1. In the abnormal connection state shown in FIG. 6, when +V is applied from the power supply 9, the voltage waveform shown by the dashed line at the bottom of FIG. 7 is monitored by the control circuit 13. In the event of an abnormality, the monitored voltage value becomes high. While FIGS. 5 and 6 show an example in which four ground circuits 4 are provided, the number of ground circuits 4 is not limited to this and may be one or more.

[0025] Since the levels (voltage values) of the waveforms shown by the solid line and dashed line are different, the control circuit 13 can determine the connection state between the frame ground 30 and the conductive elastic body 5 based on the voltage waveform detected by the monitor circuit 11.

[0026] In this embodiment, multiple ground circuits 4 are provided, and the control circuit 13 estimates the number of conductive elastic bodies 5, which are multiple ground-side connecting conductors, based on the current or voltage waveform detected by the monitor circuit 11 when the switch circuit 12 is turned on and off. When multiple ground circuits 4 are provided, the monitored voltage or current level or the slope of the voltage or current varies depending on the number of open switches. Therefore, the number of conductive elastic bodies 5 can be estimated. The quality of the electromagnetic shielding resistance of the electronic control device 1 can be determined based on the number of conductive conductive elastic bodies 5. Since the quality of the electromagnetic shielding resistance of the electronic control device 1 can be determined, it can be determined whether the electronic control device 1 requires urgent repair. For example, if four or three of the four ground circuits 4 are conductive, the electronic control device 1 can be used as is. If two or fewer of the four ground circuits 4 are conductive or all are non-conductive, the electronic control device 1 is stopped from use and repaired to restore continuity to the ground circuits 4.

[0027] Using Figures 8 to 10, we will now explain how to determine the connection status in an example configuration in which four ground circuits 4 are provided and a capacitive load 7b is used as the load 7. C1 to C4 in Figure 8 are the capacitances of the capacitive load 7b. In Figure 8, the combined capacitance C0 of the four capacitive loads 7b is expressed as C0 = C1 + C2 + C3 + C4. When +V is applied from the power supply 9 to the monitor circuit 11 (Qm is on), the applied waveform at A is shown in the upper part of Figure 10. If the connection status is normal as shown in Figure 8, the control circuit 13 monitors a waveform accompanied by a voltage change with a time constant τ = Rm × C0, which is the response time constant of the RC circuit, as shown by the solid line in the lower part of Figure 10. In the waveform shown in the lower part of Figure 10, the horizontal axis represents time and the vertical axis represents voltage.

[0028] As shown in FIG. 9, when the three conductive elastic bodies 5 shown on the right side are separated from the frame ground 30, SW2 to SW4 are open. In FIG. 9, the combined capacitance C0 is expressed as C0 = C1. In the abnormal connection state shown in FIG. 9, when +V is applied from the power supply 9, the control circuit 13 monitors a waveform accompanied by a voltage change with a time constant τ' = Rm × C0, as shown by the dashed line at the bottom of FIG. 10. In the event of an abnormality, the slope of the monitored voltage change becomes larger. While FIGS. 8 and 9 show an example in which four ground circuits 4 are provided, the number of ground circuits 4 is not limited to this and may be one or more.

[0029] Because the waveforms indicated by the solid and dashed lines are different, the control circuit 13 can determine the connection state between the frame ground 30 and the conductive elastic bodies 5 based on the voltage waveform detected by the monitor circuit 11. When the capacitive load 7b is included as the load 7, the voltage values ​​of the waveforms indicated by the solid and dashed lines differ due to the response delay until a predetermined time. This allows the control circuit 13 to estimate the number of conductive elastic bodies 5 based on the response delay of the voltage waveform. The number of conductive conductive elastic bodies 5 can be easily estimated simply by detecting the response delay of the voltage waveform. Since the number of conductive conductive elastic bodies 5 can be easily estimated, the quality of the electromagnetic shielding resistance of the electronic control device 1 can be easily determined. Furthermore, because the response time constants of the waveforms indicated by the solid and dashed lines are different, the control circuit 13 can estimate the number of conductive conductive elastic bodies 5 based on the response time constant of the voltage waveform. The number of conductive conductive elastic bodies 5 can be easily estimated simply by detecting the response time constant of the voltage waveform. Since the number of conductive elastic bodies 5 that are in electrical conduction can be easily estimated, it is possible to easily determine whether the electromagnetic shielding performance of the electronic control device 1 is good or bad.

[0030] Using Figures 11 to 13, we will now explain how to determine the connection status in an example configuration with four ground circuits 4 and an inductive load 7c as the load 7. L1 to L4 in Figure 11 are the inductances of the inductive load 7c. In Figure 11, the combined inductance L0 of the four inductive loads 7c is expressed as L0 = (L1 × L2 × L3 × L4) / (L1 × L2 × (L3 + L4) + L3 × L4 × (L1 + L2)). The control circuit 13 monitors the current change, I(t), in the monitor circuit 11. When +V is applied from the power supply 9 to the monitor circuit 11 (Qm is on), the applied waveform of A is shown in the upper part of Figure 13. If the connection status is normal as shown in Figure 11, the control circuit 13 monitors a waveform accompanied by a current change with a time constant τ = L0 / Rm, which is the response time constant of the RL circuit, as shown by the solid line in the lower part of Figure 13. In the waveform shown at the bottom of FIG. 13, the horizontal axis represents time and the vertical axis represents current.

[0031] As shown in FIG. 12, when the three conductive elastic bodies 5 shown on the right side are separated from the frame ground 30, SW2 to SW4 are open. In FIG. 12, the combined inductance L0 is represented by L0 = L1. In the abnormal connection state shown in FIG. 12, when +V is applied from the power supply 9, the control circuit 13 monitors a waveform accompanied by a current change with a time constant τ' = L0 / Rm, as shown by the dashed line at the bottom of FIG. 13. In the event of an abnormality, the slope of the monitored current change becomes smaller. While FIGS. 11 and 12 show an example in which four ground circuits 4 are provided, the number of ground circuits 4 is not limited to this and may be one or more.

[0032] Because the waveforms shown by the solid and dashed lines are different, the control circuit 13 can determine the connection status between the frame ground 30 and the conductive elastic bodies 5 based on the current waveform detected by the monitor circuit 11. When the load 7 includes an inductive load 7c, the current values ​​of the waveforms shown by the solid and dashed lines differ due to the response delay until a predetermined time. This allows the control circuit 13 to estimate the number of conductive elastic bodies 5 based on the response delay of the current waveform. The number of conductive elastic bodies 5 can be easily estimated simply by detecting the response delay of the current waveform. Since the number of conductive elastic bodies 5 can be easily estimated, the quality of the electromagnetic shielding of the electronic control device 1 can be easily determined. Furthermore, because the response time constants of the waveforms shown by the solid and dashed lines are different, the control circuit 13 can estimate the number of conductive elastic bodies 5 based on the response time constant of the current waveform. The number of conductive elastic bodies 5 can be easily estimated simply by detecting the response time constant of the current waveform. Since the number of conductive elastic bodies 5 that are in electrical conduction can be easily estimated, it is possible to easily determine whether the electromagnetic shielding performance of the electronic control device 1 is good or bad.

[0033] In the above, SW1 to SW4 have been described as being conductive elastic bodies 5, but SW1 to SW4 are not limited to being conductive elastic bodies 5. SW1 to SW4 may also be conductive non-elastic bodies 6. Even when SW1 to SW4 are conductive non-elastic bodies 6, the control circuit 13 can similarly determine the connection state.

[0034] Next, we will explain how to use the resistive load 7a, capacitive load 7b, and inductive load 7c as the load 7. The resistive load 7a, capacitive load 7b, and inductive load 7c are selected depending on the effect of the target noise and the frequency band of the noise that needs to be reduced.

[0035] When a current flows through the resistive load 7a, the resistive load 7a converts electrical energy into thermal energy. Therefore, connecting the frame ground 30 and the signal ground 20 through the resistive load 7a converts noise energy into thermal energy, thereby suppressing noise radiation. The impedance of the capacitive load 7b is inversely proportional to frequency. Therefore, connecting the frame ground 30 and the signal ground 20 through the capacitive load 7b bypasses the high-frequency components of noise, thereby suppressing radiation of unnecessary high-frequency noise. The impedance of the inductive load 7c is proportional to frequency. Therefore, connecting the frame ground 30 and the signal ground 20 through the inductive load 7c bypasses the low-frequency components of noise, thereby suppressing radiation of noise even at lower frequencies.

[0036] In this way, by using the resistive load 7a, capacitive load 7b, and inductive load 7c depending on the effect of the target noise and the frequency band of the noise that needs to be reduced, an electronic control device 1 can be obtained in which noise is appropriately suppressed by the selected load 7.

[0037] Although Fig. 5 shows a configuration in which only a resistive load 7a is provided, Fig. 8 shows a configuration in which only a capacitive load 7b is provided, and Fig. 11 shows a configuration in which only an inductive load 7c is provided, the present invention is not limited to these. For example, a configuration in which both a resistive load 7a and a capacitive load 7b are provided, and noise energy is converted into thermal energy to suppress noise radiation, while high-frequency components of the noise are bypassed to suppress radiation of unnecessary high-frequency noise. Even when multiple types of loads 7 are provided, monitoring the voltage or current waveform will cause changes in the voltage or current waveform, making it possible to estimate the number of conductive elastic bodies 5 that are in conduction.

[0038] As described above, the electronic control device 1 according to the first embodiment includes the control wiring board 2 having the signal ground 20, the housing 3 which is the frame ground 30, one or more ground circuits 4 each having a ground-side connecting conductor connected to the frame ground 30 and a load 7 connected between the ground-side connecting conductor and the signal ground 20, the monitor connecting conductor 8 connected to the frame ground 30, and the connection status detection circuit 10 including the monitor circuit 11 and the switch circuit 12 connected between the monitor connecting conductor 8 and the power supply 9, and the control circuit 13, wherein each load 7 is a resistive load 7a, a capacitive load 7b, or an inductive load 7c. The control circuit 13 has the control circuit 13 which turns on and off the switch circuit 12 to determine the connection status between the frame ground 30, the ground-side connecting conductor, the load 7, and the signal ground 20, and the connection status between the frame ground 30, the monitor connecting conductor 8, and the connection status detection circuit 10, based on the waveform of the current or voltage detected by the monitor circuit 11 when the switch circuit 12 is turned on and off. Therefore, an increase in the current consumption flowing through the connection status detection circuit 10 can be suppressed. Furthermore, the resistive load 7a, capacitive load 7b, and inductive load 7c can be selected depending on the effect of the target noise and the frequency band of the noise that needs to be reduced, so that the noise can be appropriately suppressed by the selected load 7.

[0039] When a plurality of ground circuits 4 are provided and the control circuit 13 estimates the number of conductive ground side connecting conductors based on the current or voltage waveform detected by the monitor circuit 11 when the switch circuit 12 is turned on and off, the electromagnetic shielding resistance of the electronic control device 1 can be determined depending on the number of conductive ground side connecting conductors.

[0040] When the control circuit 13 estimates the number of conductive ground connecting conductors based on the response delay of the current or voltage waveform, the number of conductive ground connecting conductors can be easily estimated simply by detecting the response delay of the current or voltage waveform. Since the number of conductive ground connecting conductors can be easily estimated, the quality of the electromagnetic shielding resistance of the electronic control device 1 can be easily determined.

[0041] When the control circuit 13 estimates the number of conductive ground connecting conductors based on the response time constant of the current or voltage waveform, the number of conductive ground connecting conductors can be easily estimated simply by detecting the response time constant of the current or voltage waveform. Since the number of conductive ground connecting conductors can be easily estimated, the quality of the electromagnetic shielding resistance of the electronic control device 1 can be easily determined.

[0042] When the connection state detection circuit 10 is provided on the control wiring board 2, the electronic control device 1 can be made smaller by providing the connection state detection circuit 10 on the control wiring board 2. Furthermore, when the conductive non-elastic body 6 is provided adjacent to the fixing screw 15 that fixes the housing 3 and the control wiring board 2, providing the conductive non-elastic body 6 adjacent to the fixing screw 15 makes it possible to accurately detect loosening or removal of the fixing screw 15.

[0043] Embodiment 2 An electronic control device 1 according to embodiment 2 will be described. Fig. 14 is a cross-sectional view that schematically shows an outline of the electronic control device 1 according to embodiment 2. The electronic control device 1 according to embodiment 2 is configured to include a plurality of ground circuits 4 and not include a monitor connecting conductor 8.

[0044] Only differences from the configuration of the electronic control device 1 shown in FIG. 1 of the first embodiment will be described. The electronic control device 1 according to the second embodiment includes multiple ground circuits 4 and no monitor connecting conductor 8, and therefore the connection configuration of the connection status detection circuit 10 differs from that of the first embodiment. The connection status detection circuit 10 includes a current or voltage monitor circuit 11 and a switch circuit 12 connected in series between a connection point 16 between one ground connecting conductor and the load 7 and the power supply 9, and a control circuit 13 that turns the switch circuit 12 on and off. In this embodiment, one ground connecting conductor is a conductive elastic body 5a. The one ground connecting conductor is not limited to the conductive elastic body 5, but may also be a conductive non-elastic body 6. The control circuit 13 determines the connection status between the frame ground 30, the ground connecting conductor, the load 7, and the signal ground 20 based on the current or voltage waveform detected by the monitor circuit 11 when the switch circuit 12 is turned on and off.

[0045] If there is a single ground circuit 4, the monitor connecting conductor 8 is necessary. If there are multiple ground circuits 4, one of the multiple ground-side connecting conductors can be used as the monitor connecting conductor 8. By setting the resistance, capacitance, or inductance of the load 7 connected to the connection point 16 to an appropriate value, one of the multiple ground-side connecting conductors can be used as the monitor connecting conductor 8, which allows the electronic control device 1 to be made smaller. Furthermore, since the monitor connecting conductor 8 is not required, the process of connecting the monitor connecting conductor 8 is not necessary, which allows the productivity of the electronic control device 1 to be improved.

[0046] Embodiment 3 An electronic control device 1 according to embodiment 3 will be described. Fig. 15 is a cross-sectional view that schematically shows the outline of the electronic control device 1 according to embodiment 3. The electronic control device 1 according to embodiment 3 has a configuration in which conductive elastic bodies 5 are provided on both sides of a control wiring board 2.

[0047] The housing 3 has one inner surface and the other inner surface that face each other via the control wiring board 2. In this embodiment, the first housing 3a has one inner surface 3a1, and the second housing 3b has the other inner surface 3b1. One surface 2b of the control wiring board 2 faces one inner surface 3a1 of the housing 3, and the other surface 2c faces the other inner surface 3b1 of the housing 3. The electronic control device 1 is provided with a monitor connection conductor 8 on the side of the one surface 2b or the other surface 2c of the control wiring board 2. At least one conductive elastic body 5 is provided opposite the monitor connection conductor 8 via the control wiring board 2, and presses against the inner surface of the housing 3 opposite the one inner surface 3a1 or the other inner surface 3b1 pressed by the monitor connection conductor 8.

[0048] In this embodiment, the electronic control device 1 includes a monitor connection conductor 8 on one surface 2b of the control wiring board 2. Therefore, one conductive elastic body 5b is provided facing the monitor connection conductor 8 via the control wiring board 2, and the conductive elastic body 5b presses against the other inner surface 3b1 of the housing 3 opposite to the one inner surface 3a1 pressed by the monitor connection conductor 8. Like the other conductive elastic bodies 5, the conductive elastic body 5b is connected to the signal ground 20 via the load 7, but the connection of the conductive elastic body 5b on the control wiring board 2 side is omitted in FIG.

[0049] With this configuration, the conductive elastic body 5b can cancel the reaction force that the control wiring board 2 receives from the housing 3 when the monitor connecting conductor 8 abuts against the inner surface of the housing 3. Because the reaction force received by the control wiring board 2 is canceled, no bending force acts on the control wiring board 2, thereby suppressing bending stress generated in the control wiring board 2. Furthermore, because the control wiring board 2 is connected to the housing 3 at multiple locations by multiple conductive elastic bodies 5, both sides of the control wiring board 2 are sandwiched between the conductive elastic bodies 5, thereby improving the vibration resistance of the control wiring board 2.

[0050] Although the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not exemplified are conceivable within the scope of the technology disclosed in this specification, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of another embodiment. [Explanation of symbols]

[0051] 1 electronic control device, 2 control wiring board, 2a main circuit, 2b one side, 2c other side, 3 housing, 3a first housing, 3a1 one inner side, 3b second housing, 3b1 other inner side, 4 ground circuit, 4a first ground circuit, 4b second ground circuit, 4c third ground circuit, 4d fourth ground circuit, 5, 5a, 5b conductive elastic body, 6 conductive non-elastic body, 7 load, 7a resistive load, 7b, 7d capacitive load, 7c inductive load, 8 monitor connection conductor, 9 power supply, 10 connection status detection circuit, 11 monitor circuit, 12 switch circuit, 13 control circuit, 14 pad, 15 fixing screw, 16 connection point, 20 signal ground, 30 frame ground

Claims

1. a control wiring board having a main circuit and a signal ground connected to the main circuit; a conductive frame ground, a housing that houses the control wiring board; one or more ground circuits each having a ground-side connecting conductor connected to the frame ground and a load connected in series between the ground-side connecting conductor and the signal ground; a monitor connection conductor connected to the frame ground; a connection state detection circuit including a current or voltage monitor circuit and a switch circuit connected in series between the monitor connection conductor and a power supply, and a control circuit for turning on and off the switch circuit; each of the ground-side connecting conductors is a conductive elastic body pressed against and connected to the frame ground, or a conductive non-elastic body connected to the frame ground, each said load is a resistive load, a capacitive load, or an inductive load; The control circuit is an electronic control device that determines the connection state between the frame ground, the ground side connecting conductor, the load, and the signal ground, and the connection state between the frame ground, the monitor connecting conductor, and the connection state detection circuit, based on the current or voltage waveform detected by the monitor circuit when the switch circuit is turned on or off.

2. a control wiring board having a main circuit and a signal ground connected to the main circuit; a conductive frame ground, a housing that houses the control wiring board; a plurality of ground circuits each having a ground-side connecting conductor connected to the frame ground and a load connected in series between the ground-side connecting conductor and the signal ground; a connection state detection circuit including a current or voltage monitor circuit and a switch circuit connected in series between a power supply and a connection point between one of the ground side connecting conductors and the load, and a control circuit for turning on and off the switch circuit; each of the ground-side connecting conductors is a conductive elastic body pressed against and connected to the frame ground, or a conductive non-elastic body connected to the frame ground, each said load is a resistive load, a capacitive load, or an inductive load; The control circuit is an electronic control device that determines the connection state between the frame ground, the ground side connecting conductor, the load, and the signal ground based on the current or voltage waveform detected by the monitor circuit when the switch circuit is turned on or off.

3. A plurality of the ground circuits are provided, 2. The electronic control device according to claim 1, wherein the control circuit estimates the number of the plurality of ground-side connecting conductors that are in a conducting state based on a waveform of a current or a voltage detected by the monitor circuit when the switch circuit is turned on or off.

4. 4. The electronic control device according to claim 3, wherein the control circuit estimates the number of the plurality of ground-side connecting conductors that are in a conducting state based on a response delay of a waveform of a current or a voltage.

5. 4. The electronic control device according to claim 3, wherein the control circuit estimates the number of the plurality of ground-side connecting conductors that are in a conducting state based on a response time constant of a current or voltage waveform.

6. the housing has one inner surface and the other inner surface facing each other with the control wiring board interposed therebetween, one surface of the control wiring board faces the one inner surface of the housing, and the other surface faces the other inner surface of the housing; The monitor connection conductor is provided on one surface or the other surface of the control wiring board, 2. The electronic control device according to claim 1, wherein at least one of the conductive elastic bodies is arranged opposite the monitor connection conductor via the control wiring board and presses against the inner surface of the housing opposite to the one inner surface or the other inner surface pressed by the monitor connection conductor.

7. The electronic control device according to claim 1 , wherein the connection state detection circuit is provided on the control wiring board.

8. 7. The electronic control device according to claim 1, wherein the conductive non-elastic body is provided adjacent to a fixing screw that fixes the housing and the control wiring board.

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