JPH083722B2 - Digital arithmetic unit for vehicle control system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle control system, and in particular, to digitally perform calculations required for controlling various driving states of a vehicle in the control system. The present invention relates to a digital arithmetic unit for a vehicle control system.

[Prior art]

Conventionally, in this type of digital arithmetic device, in order to improve the safety, economy, comfort, and high performance of the vehicle, a microcomputer is adopted, and the engine is optimized based on the optimal matching for each vehicle type or engine. The digital operation is performed so as to perform advanced control of the auto transmission, anti-skid device, navigator, etc.

[Problems to be solved by the invention]

However, in such a configuration, the ROM variations in the microcomputer unnecessarily increase, and there is a problem in that the productivity of the digital arithmetic unit, that is, the control system, is reduced and the cost is increased.

Conventionally, the following two methods have been adopted as measures against this. The first method is to use an electrically writable PROM (for example, MBM27C64 made by Fujitsu)
By writing the data to be expanded into the OM, a single mask ROM and a PROM for each vehicle type and engine are combined to solve the above problems.

However, when this first method is used, in the process of assembling the digital arithmetic unit, there is a problem in production that many PROMs that match the digital arithmetic unit are selected and assembled. Remain. Also, this PR
Since it is difficult to automate the OM selection, there is a possibility that the production cost of the digital arithmetic unit may increase.

The second method is to realize a plurality of variations with a single mask ROM by applying a specific input to a specific input terminal of the digital arithmetic unit. Specifically, this is for selecting a vehicle having an automatic transmission and a vehicle having a manual transmission, for example, when the input port for variation expansion selection is pulled up to 5V and grounded. This second method can be easily realized by assembling or not assembling a specific element (for example, a resistor) on the substrate of the digital arithmetic unit, which enables automation and labor saving, and is very suitable for mass production. , JP-A-55
-146506, JP-A-58-41242 and the like.

However, also in the second method, when the number of destinations, transmissions, engines, etc. is increased, the extra input terminals for selection are required. In particular, when a one-chip microcomputer is used, the number of input terminals is limited, so it is necessary to provide an input terminal for expansion or group mask ROMs into several groups.

In addition, changing the ROM contents for each digital arithmetic unit due to different destinations and different types of transmissions with the same engine and vehicle type reduces the productivity of the digital arithmetic unit and increases the development cost. There was also the problem of inviting.

On the other hand, for example, as disclosed in Japanese Patent Laid-Open No. 57-171045, several types of data that can be used for variation are stored in a ROM in advance, and the data AD
There is one in which one of the inputs of the converter is assigned for selection of each data and one of the data in the ROM is selected by the output of this AD converter. , A plurality of pairs of series resistors are connected between the positive side terminal and the negative side ground terminal of the DC power source, and each divided voltage generated at the common terminal between both series resistors of each pair is input to the AD converter. Even if it is done, if there are many kinds of data to be selected, an error will occur in the selection of data due to variations in the resistance value of each series resistor, changes over time, conversion errors of the AD converter, and the like. There is. In such a case, it is conceivable to reduce the number of divided voltages mentioned above or allocate the two inputs of the AD converter to select the data, but as described above within the limited space and cost. It is not enough to develop as many variations as possible.

Therefore, in order to address the above-mentioned problems, the present invention utilizes a single input terminal of the A / D converter in a digital arithmetic unit for a vehicle control system to determine three or more types. It is intended to reduce the production cost without causing errors due to specific variations of elements and changes over time.

[Means for solving problems]

In solving such a problem, a structural feature of the present invention is that voltage setting means for dividing a DC voltage from a vehicle DC power supply by a pair of series resistors, and an analog voltage set by the voltage setting means into a digital voltage. An analog / digital conversion means for converting, a storage means for storing a plurality of voltage values set corresponding to each control data for each vehicle type and each specification, and a storage means for storing the digital voltage converted by the analog / digital conversion means Storage means for selecting one of the plurality of voltage values stored by the storage means, and digital calculation means for performing vehicle calculation control based on each control data corresponding to the one voltage value selected by the selection means. Each of the plurality of voltage values stored by the means has a region of digital voltage width, and the regions of digital voltage width are adjacent to each other. The Cormorant region has a predetermined voltage range, certain digital voltage width that is an analog voltage set by the voltage setting means and broadly enough to increase.

[Action effect]

Thus, by configuring the present invention in this way,
Since the regions of the digital voltage width are stored so as to have a predetermined voltage width with the regions adjacent to each other, the digital voltage width is made wider as the analog voltage set by the voltage setting means becomes larger. If the analog voltage set by is preset to a value that belongs to one of the digital voltage widths, the control data corresponding to the digital voltage width is selected from among the control data for each vehicle type and each specification stored in the storage means. Since the selection is always made without error, the contents of the digital operation described above can be always realized based on correct data without being affected by various errors such as variations in characteristics of various elements and changes with time. In such a case, since the storage means can be configured by a single element, it is also useful for saving space and reducing production cost.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example in which the digital arithmetic unit according to the present invention is applied to a vehicle engine control system. This digital arithmetic unit has three input circuits 20a, 20b, 20c, and the input circuit 20a is an intake air amount U to the engine.
Of the intake air amount signal 10a, the battery output voltage + Vb representing the battery voltage 10b, and the cooling water temperature THW of the engine cooling system showing the cooling water temperature signal 10c, respectively. Generated as a shaped signal. The vehicle is directed to the destination D and has an automatic transmission.

The input circuit 20b includes a rotation speed signal 10d representing the engine rotation speed Ne and a vehicle speed signal 10d representing the vehicle speed SPD of the vehicle.
Each of the waveform shaping signals e is generated as a rotation speed shaping signal and a vehicle speed shaping signal, and the input circuit 20c includes a starter signal 10f indicating the start of the engine starter, a throttle signal 10g indicating the full closing of the throttle valve of the engine, An air conditioner signal 10h representing automatic control of the vehicle air conditioner, a neutral signal 10i representing shift of the vehicle automatic transmission to neutral, and an oxygen concentration signal 10j representing oxygen concentration in engine exhaust gas.
Are respectively shaped to generate a starter shaping signal, a throttle shaping signal, an air conditioning shaping signal, a neutral shaping signal and an oxygen concentration shaping signal.

In addition, the digital arithmetic unit has a set voltage generating circuit 30
And an A-D conversion circuit 40 connected to the set voltage generating circuit 30 and the input circuit 20a.
30 is composed of a pair of resistors 31, 32 connected in series with each other. In such a case, the resistor 31 is grounded at one end and is passed through the resistor 32 at the other end to a constant voltage Vc (= 5
V) is connected to the A / D conversion circuit 40.
Then, the set voltage generating circuit 30 divides the set voltage Vc by the resistors 31 and 32 and generates the divided voltage from the common terminal of the resistors 31 and 32 as the analog set voltage V1N = 0.93V. However, in this embodiment, if the resistance values of the resistors 31 and 32 are Ra and Rb, then Ra / (Ra + Rb) = 0.186.

As shown in FIGS. 1 and 2, the A / D conversion circuit 40 includes a reference voltage generator 41, a resistor 42 and a capacitor 43, an input circuit 20a, a set voltage generation circuit 30, a reference voltage generator 41, and a resistor.
42, a capacitor 43, and an AD converter 44 connected to a DC power source (not shown). The reference voltage generator 41 divides the set voltage Vc by a pair of resistors 41a, 41b connected in series with each other and divides the divided voltage by the resistors 41a, 41b.
It is generated as a reference voltage VREF (= 2V) from the common terminal of b.

The A-D converter 44 is composed of an 8-bit MB4053 type A-D converter (manufactured by Fuji Electric Communication Co., Ltd.).
The D converter 44 receives the DC voltage Vcc (= 8V) from the DC power supply at its power supply terminal and becomes in the operating state. Also, A-D
The converter 44 is grounded at its ground terminal GND, connected at its input terminal VREF to the common connection terminal of the reference voltage generator 41, and at its input terminal 16 connected to the common connection terminal of the set voltage generation circuit 30. Input circuit 20a with the remaining input terminals
Is connected to the output terminal of. In addition, the A-D converter 44
Is connected to a central processing unit 60 (hereinafter referred to as CPU 60) through a bus line 50 at its input terminal RAMP / START, its addressing input terminals A0, A1 and A2, and its output terminal RAMP / STOP. .

Then, from the CPU 60 to the input terminal VREF of the AD converter 44
When the address signal designating A is input to each address designation input terminal A0, A1 and A2 of the A / D converter 44 through the bus line 50, the A / D converter 44 receives the reference voltage VREF from the reference voltage generator 41. Is converted to digital reference voltage VREF and output from the remaining output terminal. Further, an address signal a (see FIG. 3) for designating the input terminal 16 of the AD converter 44 from the CPU 60 is passed through the bus line 50 to each address designating input terminal A0, A1 and A2 of the AD converter 44. When input, the AD converter 44 converts the analog setting voltage V1N from the setting voltage generating circuit 30 into a digital setting voltage and outputs it from the remaining output terminal. Further, an address signal for designating the remaining input terminal of the AD converter 44 from the CPU 60 passes through the bus line 50 to A-
When inputting to the addressing input terminals A0, A1 and A2 of the D converter 44, the AD converter 44 receives the intake air amount shaping signal, the battery shaping voltage and the cooling water temperature shaping signal from the input circuit 20a. A quantity signal, a digital battery voltage, and a digital cooling water temperature signal are converted and output from the remaining output terminal. The resistor 42 is fed from the output terminal RREF of the AD converter 44 to generate the constant voltage Vc. The capacitor 43 is grounded at one end and is connected to the output terminal CH of the AD converter 44 at the other end.

In such a case, the AD conversion time TR of the AD converter 44 is determined as follows. The low level signal b (see FIG. 3) from the CPU 60 passes through the bus line 50 and the AD converter 44.
Input to the input terminal RAMP / START of the AD converter 44
Causes the charging current IR to flow into the capacitor 43 from its output terminal CH, and during the generation of the low level signal b, the capacitor
The capacitor 43 is charged until the charging voltage VCH (see FIG. 3) of 43 reaches the analog set voltage V1N to the input terminal 16. Then, when the low-level signal b rises, the AD converter 44 stops giving the charging current IR to the capacitor 43,
At the same time, the capacitor 43 begins to discharge and the charging voltage VCH is lowered with a predetermined slope θ (= IR / VCH). In addition,
In FIG. 3, reference character C is the output terminal of the AD converter 44, RAMP · ST.
Indicates a high level signal originating from OP.

Here, assuming that the capacitance of the capacitor 43 is CH and the resistance value of the resistor 42 is RREF, the following relational expression is established.

IR = (Vc-VREF) / RREF ・ ・ ・ (1) TR = V1N × CH / IR ・ ・ ・ (2) Therefore, by substituting equation (1) into equation (2), TR = V1N × RREF × CH / (VC-VREF) (3) is obtained. By the way, RREF = 90.90KΩ, CH = 0.0068μF
Then, from the formula (3), TR = 206.04 × V1N (μs) (4). For example, when V1N = 5V, TR = 1030.2 μs.

When the A-D conversion error e of the A-D converter 44 is examined, there are the following three items as the factors of the A-D conversion error.

1. Error due to constant voltage Vc e1 Vc = 5.00 ± 0.05 V, e1 = ± 10.3 × V1N / Vc (μs) 2. Linearity error of A-D conversion time TR e2 Uniformly ± 0.2%, TR = 1030.2 (μs), e2 = 1030.2 × (± 0.2%) 3. Error due to resistor 42 and capacitor 43 e3 RREF = 90.9KΩ (± 1%) CH = 0.0068μF (± 2%) e3 = ± It becomes 3%. For example, at V1N = 5V, the worst is 30.9
The error is (μs).

Therefore, each error e1, e2 and e3 of e3 = ± 30.9 x V1N / Vc or more
Then, the AD conversion error is e = e1 + e2 + e3 = ± 41 × V1N / Vc ± 2.1 (μs) ...
(5) The CPU 60, as shown in FIG. 1, via the bus line 50, both input circuits 20b, 20c, and the read-only memory 70.
(Hereinafter referred to as ROM70), random access memory 8
It is connected to 0 (hereinafter referred to as RAM 80) and output circuit 90, and this CPU 60 has both input circuits 20b, 20c and AD conversion circuit.
In cooperation with 40, ROM70 and RAM80, the computer program stored in advance in ROM70 is executed according to the flowchart shown in FIG. 4, and during this execution, arithmetic processing necessary for controlling the injector INJ and igniter IGT of the engine is performed. The output is passed through the output circuit 90 and the injector INJ
And given to the igniter IGT.

In addition, in the present embodiment, as shown in (Table 1) below, each pair of ignition control data and fuel injection control data
Ai, Af; Bi, Bf; Ci, Cf; Di, Df; ...; Li, Lf; Mi, Mf are each A-
D conversion value width (digital voltage width) ΔW1, ΔW2, ΔW3,
..Preliminarily stored in the ROM 70 in association with .DELTA.W12 and .DELTA.W13. In such a case, as is clear from (Table-1), each ΔW1, ΔW2, ΔW3, ... ΔW12, ΔW13 has an AD conversion value width (digital voltage) so that the above AD conversion error e can be absorbed. The width (width) area is provided with a predetermined voltage width with the area adjacent to each other, and the A / D conversion value width (digital voltage width) becomes wider as the analog set voltage VIN increases. Here, the reason why the A-D converted value width (digital voltage width) is made wider as the analog set voltage VIN becomes larger is that the analog set voltage VIN becomes larger as the analog set voltage VIN becomes larger, as is clear from the above equation (5). This is because the conversion error e becomes large.

In addition, each pair of control data Ai, Af and Hi, Hf is the destination A.
For the destination vehicle, each pair of control data Bi, Bf and Ii, If for the destination B vehicle, each pair of control data Ci, Cf and Ji, Jf for the destination C vehicle, and each pair of the control data Di. , Df and Ki, Kf are for the destination D vehicle (that is, the vehicle), each pair of control data Ei, Ef and Li, Lf are for the destination E vehicle, and each pair of control data Fi, Ff, Mi. , Mf correspond to the destination F vehicle, and the pair of control data Gi, Gf correspond to the destination G vehicle. In such a case, the vehicle corresponding to each control data Ai ~ Fi and Af ~ Ff is equipped with an automatic transmission, and the vehicle corresponding to each control data Hi ~ Mi and Hf ~ Mf is equipped with a manual transmission. . Further, the transmission of the vehicle corresponding to each control data Gi, Gf may be either an automatic transmission or a manual transmission. Also,
The correspondence between V1N, {Ra / (Ra + Rb)} and ΔWi is (Table-
It is designed as in 1).

In the present embodiment configured as described above, if the engine of the vehicle is started under the operation of the engine control system, the CPU 60 starts executing the computer program in step 100 according to the flowchart of FIG. Each input circuit 20a, 20b, 20c, RAM80 and output circuit 90
Is initialized. At this time, the contents stored in the RAM 80 are all cleared, and the input ports of the input circuits 20a, 20b, 20c and the output port of the output circuit 90 are set to a predetermined state. Then the computer program proceeds to step 120.
Proceeding to step, the CPU 60 redefines the above-mentioned input ports and output ports. As a result, when the device of the present invention is continuously operated for a long time, even if the above-defined state changes due to an ignition nozzle, electromagnetic interference, or the like, the normal state can be promptly restored.

Next, when the computer program proceeds to the fuel injection time calculation routine 130, the CPU 60 calculates the fuel injection time of the injector INJ as follows. That is, when the A / D converter 44 converts the analog setting voltage V1N (= 0.93V) from the setting voltage generating circuit 30 into a digital setting voltage as described above, the CPU 60 causes the A / D conversion to which the digital setting voltage belongs. The ignition control data Di and the fuel injection control data Df are stored in the ROM 70 according to the relationship with the value width ΔW4 (= 178 to 204).
Select

In such a case, the fuel injection control data Df corresponds to the following relational expression.

τ = TP × FAF × FWL × (1 + FAEW + FOTP + FASE) + τV ・
・ ・ (6) However, τ: Fuel injection time TP: Basic fuel injection time (TP = K / UNe) FAF: Air-fuel ratio correction coefficient determined by oxygen concentration signal 10j FWL: Warm amount increase correction determined by cooling water temperature signal 10c Coefficient FAEW: Acceleration increase correction coefficient determined by differential value of intake air amount signal 10a and cooling water temperature signal 10c FOTP: Overheat increase correction coefficient determined by Ne, U FASE: Post-start increase correction coefficient determined by cooling water temperature signal 10c τV: When the invalid injection time determined by the battery voltage 10b is required, each correction coefficient has a value unique to the vehicle for the destination D equipped with the automatic transmission.

When the fuel injection control data Df is selected as described above,
The CPU 60 cooperates with the input circuit 20a based on the intake air signal 10a, the battery voltage 10b and the cooling water temperature signal 10c to input the AD conversion output of the AD converter 44, the rotation speed signal 10d and the vehicle speed signal 10e. Output of circuit 20b and oxygen concentration signal 10j
Based on the output of the input circuit 20c, the fuel injection time τ is calculated from the relational expression (6), and is given to the injector INJ as an injection signal through the output circuit 90. In such a case, as described above, the AD conversion value of the AD converter 44 with respect to the analog set voltage V1N (= 0.93V) always belongs to ΔW4 (= 78 to 204) regardless of the conversion error. Since the resistance value of each resistor 31, 32 of the set voltage generation circuit 30 is specified in
The 60 does not erroneously select other data in the ROM 70, so that the fuel injection time is properly determined under the correct fuel injection control data that always matches the specifications of the vehicle.

Computer program routine for ignition timing calculation 14
Proceeding to 0, the CPU 60 calculates the high voltage generation timing of the igniter IGT (that is, the ignition timing of the engine) as follows. That is, when the A / D converter 44 converts the analog setting voltage V1N (= 0.93V) from the setting voltage generating circuit 30 into a digital setting voltage as in the above, the CPU 60 causes the A / D conversion to which the digital setting voltage belongs. The ignition control data Di and the fuel injection control data Df are selected from the stored contents in the ROM 70 in association with the value width ΔW4 (= 178 to 204). In such a case, the ignition control data Di is composed of a map showing the relationship between the opening of the throttle valve, the rotation speed Ne, the condition of the air conditioner, the condition of the automatic transmission, the vehicle speed and the ignition timing of the engine. The map is specific to the specifications of the vehicle. For example, the ignition timing when the throttle signal 10g is generated is specified by the presence or absence of the generation of the neutral signal 10i, that is, the automatic transmission. The ignition timing when the throttle signal 10g disappears is also specified by the destination D.

When the ignition control data Di is selected as described above, the CPU6
Input circuit 2 in which 0 is based on the rotation speed signal 10d and the vehicle speed signal 10e
0b output and starter signal 10f, throttle signal 10g,
The ignition timing is calculated from the map according to the output of the input circuit 20c based on the air conditioner signal 10h and the neutral signal 10i, and is given to the igniter IGT as an ignition signal through the output circuit 90. In such a case, as described above, the analog setting voltage V1N
The AD conversion value of the AD converter 44 with respect to (= 0.93V) is ΔW4 (= 78 to 20) regardless of the conversion error.
4) Each resistor 31 of the set voltage generating circuit 30 should always belong to
Since the resistance value of 32 is defined, the CPU 60 does not erroneously select other data in the ROM 70, and as a result, the ignition timing is based on the correct ignition control data that always matches the specifications of the vehicle. Properly required.

In the present embodiment, an example in which the resistance values of the resistors 31 and 32 of the set voltage generating circuit 30 are set to satisfy {Ra / (Ra + Rb)} = 0.186 has been described. , {Ra / Ra + Rb)} takes any of the other values in (Table-1), the resistance value of each resistor 31, 32 is set to C
The PU 60 controls the ignition control data and the fuel injection data in relation to each {Ra / (Ra + Rb)}, that is, the AD conversion value width ΔWi to which the AD conversion value of the AD converter 44 with respect to each analog set voltage V1N belongs. Is selected from the stored contents of the ROM 70 for each vehicle destination and each type of transmission. In such a case, as can be seen from (Table-1), the A-D converted value widths ΔWi are arranged in the order in which they do not overlap with each other and have the least influence, and therefore the output of the A-D converter 44 is used to determine the vehicle. Therefore, the control data that matches the specification of can be always selected correctly, and as a result, the fuel injection control and the ignition control that match the specification of the vehicle can always be realized.

Further, in carrying out the present invention, the present invention is not limited to the fuel injection control and the ignition control of the engine, and the present invention can be applied to the automatic drive control of the vehicle, the anti-skid control and the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a detailed circuit diagram of the A-D conversion circuit in FIG. 1, and FIG. 3 is a waveform diagram showing the operation of the A-D conversion circuit. And FIG. 4 is a flow chart for the CPU in FIG. Explanation of symbols 30 …… Set voltage generation circuit, 31,32 …… Resistance, 40 …… AD
Conversion circuit, 60 …… CPU, 70 …… ROM.

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-58-10203 (JP, A) JP-A-56-127202 (JP, A) JP-A-57-171045 (JP, A) JP-A-55- 45249 (JP, A)

Claims (1)

[Claims] 1. A voltage setting means for dividing a DC voltage from a vehicle DC power supply by a pair of series resistors, an analog / digital converting means for converting an analog voltage set by the voltage setting means into a digital voltage, and a vehicle type. Storage means for storing a plurality of voltage values set corresponding to each control data for each and for each specification, and a plurality of voltage values stored by the storage means from the digital voltage converted by the analog / digital conversion means A plurality of units stored in the storage unit, the selection unit selecting one of the plurality of storage units, and the digital calculation unit performing vehicle calculation control based on the control data corresponding to one voltage value selected by the selection unit. Each of the voltage values has a digital voltage width region, and the region where the digital voltage width regions are adjacent to each other has a predetermined value. Has a pressure range, digital operation device for a vehicle control system characterized in that analog voltage set has wide enough to increase by the voltage setting unit said digital voltage width.