JP2012114218A - Control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control apparatus which takes noise measures to ground or the like and processes sensor output which is input with high accuracy while suppressing the cost increase.SOLUTION: A control apparatus processes electric signals from a sensor 7 detecting physical values and outputs electric signals controlling a control object. The control apparatus includes: an inner ground part 2 to which the sensor 7 and the control object electrically connect, a power supply circuit 4 supplying electric power for driving the sensor 7 and electrically connecting to the inner ground part 2, and a processing unit 3 performing arithmetic processing for the electric signals from the sensor 7 and electrically connecting to the inner ground part 2.

Description

  The present invention relates to a control device, and more particularly to a control device that processes an electrical signal from a sensor that detects a physical value and outputs an electrical signal that controls a control target.

  In general, the control device requires a highly accurate sensor output (physical value) so as not to cause the control target to malfunction. The control device normally uses the sensor output as a differential output from the ground (GND), and uses the differential output for A / D conversion to control the control target by performing arithmetic processing.

  However, in an environment where the influence of noise such as a vehicle is strong, the noise enters the GND or the like and its potential fluctuates, and the difference output based on the sensor output becomes inaccurate including the influence of noise. There is.

  Therefore, conventionally, for example, in a vehicle-mounted electronic device, (i) a sensor ground (SG) or a logic ground (LG) that is different from the GND where noise is likely to ride is drawn from an alternator, and (ii) protection from electromagnetic noise Therefore, many countermeasures against noise have been taken, such as protecting the board with an aluminum case, and (iii) using a bypass capacitor or solenoid.

  Further, in Patent Document 1, as a noise countermeasure, the internal GND of the vehicle-mounted electronic device, the housing, and the vehicle body are electrically connected, and a low-pass filter is provided between the vehicle-mounted electronic device and the power source. It is disclosed.

  Furthermore, Patent Document 2 discloses that an electrostatic protection element (such as a resistor) is provided between a control ground and a case ground in an automotive control device.

Japanese Utility Model Publication No. 64-37345 Japanese Patent No. 4005794

  However, when SG or LG of a different system from the conventional GND is provided, a bypass capacitor or a solenoid is used, or a filter or an electrostatic protection element as disclosed in References 1 and 2 is used, mounting them For this reason, the board size of the control device increases or the number of parts increases, which increases the cost of the control device.

  Therefore, an object of the present invention is to provide a control device capable of accurately processing an input sensor output while taking measures against noise to GND and the like while suppressing an increase in cost.

  The present invention provides a control device that processes an electrical signal from a sensor that detects a physical value and outputs an electrical signal that controls a control target. The control device calculates an electrical signal from the sensor, an internal ground part to which the sensor and the controlled object are electrically connected, a power supply circuit that supplies power for driving the sensor and is electrically connected to the internal ground part And an arithmetic unit that performs processing and is electrically connected to the internal ground portion.

  According to the present invention, the number of parts can be reduced by connecting the sensor and the controlled object to a common internal ground portion. In addition, although noise from the control target may enter the internal ground portion, the power supply circuit that operates the sensor and the arithmetic device are also connected to the internal ground portion, so that the electric signal from the sensor is processed by the arithmetic device. In the process, the influence of the noise can be canceled.

  According to an aspect of the present invention, the control device is housed in one housing, the housing functions as a case ground for shielding the control device from noise, and the internal ground portion is connected to the case ground directly. A ground portion and a second ground portion that is electrically upstream of the first ground portion, the control target is connected to the first ground portion, and the sensor and the power supply circuit are connected to the second ground portion. .

  According to an aspect of the present invention, the first ground portion is electrically upstream of the second ground portion, and therefore the sensor connected to the first ground portion is affected by noise entering the second ground portion. It becomes difficult to receive.

  According to one aspect of the present invention, the control device is used in a vehicle, and the casing is directly connected to the vehicle body frame that functions as a frame ground.

  According to one form of this invention, the wire harness used for a connection with GND can be reduced by using a frame ground and a case ground. In addition, noise may enter the frame ground, but the sensor is not easily affected by the noise due to the configuration of the first and second ground portions of one embodiment of the present invention described above.

It is a basic lineblock diagram of the control device according to an embodiment of the present invention. It is a figure which shows the time change of GND, Vcc, and the output of a sensor according to embodiment of this invention. It is a figure which shows the time change of the output value after A / D conversion of the output of the sensor according to embodiment of this invention. It is a block diagram of the control apparatus according to embodiment of this invention. FIG. 5 is an equivalent circuit diagram of the configuration of FIG. 4 according to an embodiment of the present invention. It is a figure which shows the connection relation of the GND line around the control apparatus according to embodiment of this invention.

  Embodiments of the present invention will be described with reference to the drawings. Note that the following description assumes that the control device of the present invention is mounted on a vehicle, but the embodiment of the present invention is not limited to this, and is also used to control other machines and devices other than the vehicle. Needless to say, it can be applied.

  FIG. 1 is a basic configuration diagram of a control device according to an embodiment of the present invention. A substrate 1 of an electronic control unit (hereinafter referred to as “ECU”) corresponding to a control device is provided with an internal ground (hereinafter referred to as “GND”) 2 at the periphery thereof. The internal GND 2 of the ECU board 1 is directly connected to a housing (case) 10 containing the ECU board 1 by a contact 9 made of a conductive material such as metal. The housing 10 is made of a conductive material such as metal (for example, aluminum) and functions as a case ground for shielding the ECU from noise. The housing 10 is electrically connected to an alternator (not shown) in the vehicle through a vehicle body (not shown).

  Therefore, the internal GND 2 of the ECU board 1 can be directly connected to the GND of the alternator via the contact 9, the housing 10 and the vehicle body. As a result, it is not necessary to connect the GND of the ECU board 1 to the GND of the alternator using a wire harness as in the prior art, and the wire harness cost can be reduced. At the same time, the heat generated in the ECU can be dissipated by the heat conduction path passing through the internal GND2-> contact 9-> housing 10-> car body, so that it is possible to improve heat dissipation.

  The ECU board 1 is provided with a central processing unit (hereinafter referred to as “CPU”) 3 and a power source (hereinafter referred to as “Vcc”) 4 corresponding to the arithmetic unit. The CPU 3 and Vcc 4 are electrically connected to the internal GND 2 via GND lines 5 and 6, respectively.

  The Vcc 4 supplies a drive voltage (for example, 5 V) for driving the CPU 3 in the ECU board 1 and the external sensor 7 to each of them. Although only one sensor 7 is shown in FIG. 1, there are actually a plurality of various sensors, and Vcc 4 supplies a driving voltage corresponding to each sensor. The sensor 7 is electrically connected to the internal GND 2 via a GND line (SG) 8.

  Although not shown, the ECU is a computer including an input / output interface, a memory, and the like in addition to the CPU 3. The memory can store a computer program for realizing various controls and data necessary for executing the program. Programs for various controls according to the present invention, and data and maps used in executing the programs are stored in a memory. The CPU 3 receives the detection signal sent from the sensor 7 or the like, performs calculation, and sends a control signal to each control target.

  Next, an embodiment of sensor output control (processing) by the control device of FIG. 1 will be described with reference to FIGS. The processing described below is executed by the CPU 3. FIG. 2 shows temporal changes in the voltages of the internal GND 2 and Vcc 4 and the output Vout (voltage) of the sensor 7. FIG. 3 shows the output (voltage) after A / D conversion of the output Vout of the sensor 7.

  As shown by the line 10 in FIG. 2, it is assumed that the voltage of the internal GND 2 that should be zero originally fluctuates due to the influence of noise. At this time, the output of Vcc 4 electrically connected to the internal GND 2 also varies as shown by the line 11 due to the influence of the voltage variation of the internal GND 2 due to noise. Since the sensor 7 is driven by the voltage of Vcc4 affected by the noise and the voltage of the internal GND2, the output Vout of the sensor 7 fluctuates under the influence of noise as indicated by the line 12.

  Therefore, in one embodiment of the present invention, the output Vout of the sensor 7 is not A / D converted as it is, but the difference (Vout-GND voltage) between the output Vout and the voltage of the internal GND 4 is A / D converted. By taking this difference, the influence of noise in Vout and the GND voltage can be canceled. As a result, it is possible to obtain a sensor output value after A / D conversion in which the influence of noise as shown by the line 13 in FIG. 3 is reduced or eliminated.

  Thus, according to the embodiment illustrated in FIG. 1 of the present invention, the number of parts such as a wire harness can be reduced by connecting the sensor 7 and the vehicle to be controlled to the common internal GND 2. . Even if noise from the vehicle enters the internal GND 2, the Vcc 4 that operates the sensor 7 and the CPU 3 are connected to the internal GND 2. Therefore, in the process of processing the electrical signal from the sensor 7 by the CPU 3, The influence can be canceled.

  Next, details of the control device according to the embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a configuration diagram of the control device according to the embodiment of the present invention. FIG. 5 is an equivalent circuit diagram of the configuration of FIG. FIG. 6 is a diagram showing the connection relationship of the GND lines around the control device of the present invention.

  In FIG. 4, a housing (case) 10 that encloses the ECU board 1 is connected to a GND (hereinafter referred to as “frame ground” or “FG”) 22 of a vehicle body frame via a contact 21 made of a conductive material such as metal. Connected directly. As in the case of FIG. 2, the housing 10 is made of a conductive material such as a metal (for example, aluminum) and functions as a case ground. The ECU board 1 is composed of a circuit board such as a printed wiring board.

  The ECU board 1 is provided with two types of GNDs connected to each other as internal GNDs. One is a large current system GND 24 and the other is a small current system GND 25. The large current system GND 24 is arranged near the periphery of the ECU board 1 as shown in the figure, and is directly connected to the housing 10 functioning as a case ground via a connection structure 26 made of a conductive material such as metal (plated copper or the like). Is done. The small current system GND 25 is disposed relatively inside the peripheral portion of the ECU board 1. Both the large current system GND 24 and the small current system GND 25 are made of a conductive material such as metal (plated copper or the like). The wiring pattern of the large current system GND 24 is designed to have a (length / width) ratio smaller than that of the small current system GND 25. This is to prevent the amount of heat generated according to the resistance value from becoming too large even when a large current flows.

  The number of parts such as a conventionally used wire harness can be reduced by the arrangement of the GNDs in FIG. 4 and the direct connection configuration thereof. Specifically, for example, as illustrated in FIG. 6, a wire harness (for example, LG, PG, etc.) for establishing a GND connection between the vehicle body frame 41 connected to the engine 42 and the battery 44 and the ECU board 1. And can be connected directly as FG. The GND connection between the sensor 7 and the ECU board 1 is performed by a sensor ground (SG) as in the conventional case. At the same time, the heat generated by the ECU can be directly conducted to the housing 10 and further to the vehicle body frame 41, so that the heat dissipation can be improved.

  Returning to FIG. 4, the ECU board 1 is provided with a CPU 3 and a regulator 30. The CPU 3 and the regulator 30 are electrically connected to the small current system GND 25 via GND lines 27 and 28, respectively. The regulator 30 is connected to an external AC generator (ACG, alternator) 37 via a power line 29. The regulator 30 converts the supply voltage (for example, 14 V) from the AC generator 37 into a predetermined voltage (for example, 5 V), and supplies the predetermined voltage to the CPU 3 and the external low-power device 38 via the power line 31. The low power device 38 is a device that is driven by relatively small power (current), and corresponds to, for example, an atmospheric pressure sensor or a temperature sensor. The small power device 38 is electrically connected to the small current system GND 25 via the GND line 33. A detection signal of the low power device 38 is sent to the CPU 3 through the signal line 35.

  A supply voltage (for example, 14 V) from the AC generator 37 is further supplied to the high power device 39 via the power supply line 29. The large power device 39 is electrically connected to the large current system GND 24 via the GND line 34. The high power device 39 is a device that is driven by relatively large power (current), and corresponds to, for example, a fuel supply device, an automatic transmission, and the like.

  4 can be expressed as an equivalent circuit diagram as shown in FIG. In FIG. 5, the regulator 30, the small current system GND 25, and the large current system GND 24 already described in FIG. 4 are arranged in the ECU board 1 in order from the electrical (voltage) upstream side, that is, from the side closer to the power supply V. The The large current system GND 24 is connected to the FG 22. The low power device 38 is electrically connected to the regulator 30 and the small current system GND 25. The large power device 39 is electrically connected to the external power supply V and the large current system GND 24.

  5, that is, by arranging the small current system GND 25 and the regulator 30 upstream of the large current system GND 24 connected to the FG 22 electrically (voltage), the output of the regulator 30 and the small current system GND 25 The influence of noise on the driven low-power device 38 can be canceled out. In other words, the small current system GND 25 that is synchronized with the noise of the large current system GND 24 is arranged by arranging the small current system GND 25 above the large current system GND 24 and generating a predetermined voltage (for example, 5 V) using the small current system GND 25. And a predetermined voltage (for example, 5V) can be output, and as a result, the influence of noise on the low-power device 38 driven by them can be canceled.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and can be modified and used without departing from the spirit of the present invention.

1 ECU board 2 Internal ground 3 CPU
4 Power supply 10 Case (case)
22 frames GND (FG)
24 Large Current GND
25 Small current system GND
30 Regulator

Claims (3)

A control device that processes an electrical signal from a sensor that detects a physical value and outputs an electrical signal that controls a controlled object,
An internal ground part to which the sensor and the controlled object are electrically connected;
A power supply circuit that supplies power for driving the sensor and is electrically connected to the internal ground portion;
A control device comprising: an arithmetic device that arithmetically processes an electrical signal from the sensor and is electrically connected to the internal ground portion. The control device is housed in one housing, and the housing functions as a case ground for shielding the control device from noise,
The internal ground portion includes a first ground portion that is directly connected to the case ground, and a second ground portion that is electrically upstream of the first ground portion,
The control device according to claim 1, wherein the control target is connected to the first ground part, and the sensor and the power supply circuit are connected to the second ground part.   The control device according to claim 2, wherein the control device is used in a vehicle, and the casing is directly connected to a vehicle body frame that functions as a frame ground.

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