Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2002-08-06
2004-05-04
Vo, Hieu T. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S115000, C701S102000, C701S001000
Reexamination Certificate
active
06732044
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicular electronic control apparatus that incorporates a microprocessor and is used for fuel supply control of a vehicle engine. In particular, the invention relates to a vehicular electronic control apparatus that is miniaturized and standardized by improving how to handle a lot of input and output signals as well as improved in safety.
2. Description of the Related Art
FIG. 14
is a block circuit diagram of a conventional vehicular electronic control apparatus.
In
FIG. 14
, reference numeral
1
denotes an ECU (engine control unit) formed on a single printed circuit board and reference numeral
2
denotes a large-sized LSI (integrated circuit part) of the ECU
1
. The LSI
2
is configured in such a manner that a CPU (microprocessor)
3
, a nonvolatile flash memory
4
, a RAM
5
, an input data selector
6
, an A/D converter
7
, an output latch memory
8
, etc. are connected to each other. Reference numeral
9
denotes a power supply unit for supplying control power to the ECU
1
;
10
, a vehicle battery;
11
, a power line that connects the vehicle battery
10
and the ECU
1
; and
12
, a power switch.
The ECU
1
operates being supplied with control power from the power supply unit
9
that is supplied with power by the vehicle battery
10
via the power line
11
and the power switch
12
. Programs to be executed by the ECU
1
, control constants for engine control, etc. are stored in the nonvolatile flash memory
4
in advance.
Reference numeral
13
denotes various sensor switches;
14
, bleeder resistors;
15
, series resistors;
16
, parallel capacitors;
17
, input resistors;
18
, positive feedback resistors; and
19
, comparators. Each of a lot of ON/OFF input signals coming from the various sensor switches
13
is supplied to the associated comparator
19
via the bleeder resistor
14
as a pull-up or pull-down resistor and the series resistor
15
and the parallel capacitor
16
which constitute a noise filter. The input resistor
17
and the positive feedback resistor
18
are connected to each comparator
19
. If the voltage across a certain parallel capacitor
16
exceeds a reference voltage that is applied to the negative-side terminal of the associated comparator
19
, the comparator
19
supplies a signal having a logical value “H” to the data selector
6
.
When the voltage across a certain parallel capacitor
16
decreases, addition of a voltage that is fed back by the positive feedback resistor
18
occurs and hence the output voltage of the comparator
19
does not return to a logical value “L” until the voltage across the parallel capacitor
16
becomes lower than the reference voltage.
As described above, each comparator
19
has the function of a level judgment comparator including a hysteresis function. Outputs of the many comparators
19
are stored in the RAM
5
via the data selector
6
and a data bus
30
.
The data selector
6
, which handles inputs of 16 bits, for example, outputs signals to the data bus
30
when receiving a chip-select signal from the CPU
3
. Actually a plurality of data selectors
6
are used because there exist tens of input points.
Reference numeral
20
denotes various analog sensors;
21
, series resistors; and
22
, parallel capacitors.
Each of a lot of analog signals coming from the various analog sensors
20
is supplied to the associated A/D converter
7
via the series resistor
21
and the parallel capacitor which constitute a noise filter. A digital output of an A/D converter
7
that has received a chip-select signal from the CPU
3
is stored in the RAM
5
via the data bus
30
.
A control output of the CPU
3
is stored in the latch memory
8
via the data bus
30
, and is used for driving an external load via the associated output transistor
23
. Actually a plurality of latch memories
8
to accommodate a lot of control outputs. Control outputs are stored in a latch memory
8
that has been chip-selected by the CPU
3
.
Reference numeral
24
denotes drive base resistors for the respective transistors
23
;
25
, stabilization resistors each of which is connected between the base and the emitter of the associated transistor
23
;
26
, external loads; and
27
, a power relay for supplying power to the external loads
26
.
The conventional apparatus having the above configuration has the following problems. The LSI
2
has a large scale because the CPU
3
handles a very large number of inputs and outputs. The parallel capacitors
16
and
22
which constitute noise filters need to have various capacitance values to obtain desired filter constants, and hence it is difficult to standardize the parallel capacitors
16
and
22
. A large capacitor is needed to obtain a large filter constant, which is a factor of increasing the size of the ECU
1
.
Among measures for decreasing the size of the LSI
2
by decreasing the number of input and output terminals is a method of exchanging a lot of input and output signals in a time-divisional manner using a serial communication block as disclosed in Japanese Patent Laid-Open No. 13912/1995 (title: Input/output processing IC).
However, this method requires noise filters having various capacitance values and hence is not suitable for standardization of an apparatus. Further, this method is not suitable for miniaturization of an apparatus either because large capacitance values are needed to obtain sufficiently large filter constants.
On the other hand, a concept is known that a digital filter is used as a noise filter for an on/off input signal and its filter constant is controlled by a microprocessor.
For example, Japanese Patent Laid-Open No. 119811/1993 (title: Programmable controller) discloses a method in which if sampled input logical values of an external input signal have the same value plural times that value is employed and stored in an input image memory, and in which a filter constant changing instruction capable of changing the sampling period is provided.
Although this method has an advantage that the filter constant can be changed freely, the microcomputer is caused to bear a heavy load when a lot of input signals need to be processed. As a result, the response speeds of control operations of the microprocessor lower though the control operations are primary operations of the microprocessor.
Japanese Patent Laid-Open No. 2000-89974 (title: Data storage control device) also discloses a digital filter for an on/off signal. A shift register is provided as hardware and sampling processing is performed according to the same concept as described above.
Japanese Patent Laid-Open No. 83301/1997 (title: Switched capacitor filter) discloses a digital filter using a switched capacitor which serves as a noise filter for multi-channel analog input signals.
Also in this case, the microcomputer is caused to bear a heavy load when a lot of analog input signals need to be processed. As a result, the response speeds of control operations of the microprocessor becomes even lower though the control operations are primary operations of the microprocessor.
Japanese Patent Laid-Open No. 305681/1996 (title: Microcomputer) discloses a filter in which the filter constant is changed by switching, in multiple steps, the resistor of an analog filter that consists of a resistor and a capacitor. Japanese Patent Laid-Open No. 2000-68833 (title: Digital filter system) discloses a moving average type digital filter in which the arithmetic mean value of a plurality of time-series sampling data is employed as data of current time after analog values are converted into digital values.
Various known techniques relating to watching for a runaway and reactivation control of a microprocessor that should be pointed out in connection with the invention are as follows.
Japanese Patent Laid-Open No. 196003/1995 (title: Control system of vehicular safety device) discloses the following. An AND circuit is provided in a driving circuit of a vehicular safety device that is drive-controlled by a microcomputer. Th
Hashimoto Kohji
Nakamoto Katsuya
Mitsubishi Denki & Kabushiki Kaisha
Sugrue Mion, PLLC
Vo Hieu T.
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