JP4151220B2 - Engine output control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine output control device that controls engine output in response to load fluctuations caused by power steering (hereinafter referred to as power steering).
[0002]
[Prior art]
A technique is known in which engine output is controlled in response to load fluctuations caused by power steering in order to prevent fluctuations in engine rotation speed due to load fluctuations caused by power steering (see JP-A-11-107800). With this technology, the power steering steering assist force generation hydraulic pressure (power steering hydraulic pressure) is detected as the power steering load, and the engine output is corrected according to the power steering hydraulic pressure in the steady state to prevent fluctuations in the engine speed due to load fluctuations. is doing. Furthermore, in this technology, in order to prevent fluctuation (decrease) in the engine rotation speed when the power steering oil pressure suddenly increases as in the case where the steering angle is steered from immediately before the maximum steering angle to the maximum, When the amount of change is greater than or equal to a predetermined value, the power output is regarded as the maximum value, and the engine output is corrected, thereby responding to a sudden load fluctuation at the time of transition.
[0003]
[Problems to be solved by the invention]
However, in the above-described prior art, if the amount of change in the power steering oil pressure is equal to or greater than a predetermined value, the power steering oil pressure is uniformly regarded as the maximum value, and therefore a situation in which the engine output is increased more than necessary is likely to occur. For this reason, in the above-described conventional technology, although fluctuations in the engine speed due to load fluctuations in power steering can be prevented, there is a risk that the fuel consumption will be deteriorated due to an increase correction in engine output more than necessary.
[0004]
The present invention was devised in view of such problems, and provides an engine output control device that can reliably prevent fluctuations in engine rotation speed due to power steering load fluctuations while suppressing wasteful fuel consumption. For the purpose.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the engine output control device of the present invention, the power steering oil pressure detecting means detects the hydraulic pressure for generating the steering assist force of the power steering, and the oil pressure change amount detecting means detects the oil pressure change amount. A first correction amount that increases in proportion to an increase in the oil pressure detected by the power steering oil pressure detection means, and a second correction amount that increases in proportion to an increase in the oil pressure change amount detected by the oil pressure change amount detection means; Is added to calculate the power steering correspondence correction amount, and the engine output is corrected by the engine output correction means based on the calculated power steering correspondence correction amount. When the hydraulic pressure change amount reaches the peak value and changes in the decreasing direction, the power steering correspondence correction amount is calculated. It is characterized in that it constitutes the engine output correcting means so as gradually to reduce the second correction amount gradually.
[0006]
Preferably, the engine output correction means is configured to limit the power steering correction amount to the maximum correction amount when the power steering correction amount is equal to or greater than a predetermined maximum correction amount .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram of a vehicle according to an embodiment of the present invention, and shows a configuration of a steering unit and an engine control system.
Here, the steering unit is configured as a power steering system (power steering) 3, and applies a steering assist force by the hydraulic cylinder 11 to the rotation operation of the steering wheel 10. The hydraulic cylinder 11 has a pair of left and right hydraulic chambers 11a and 11b with a piston 11c interposed therebetween, and hydraulic pipes 20 and 21 are connected to the hydraulic chambers 11a and 11b via control valves 12, respectively. The hydraulic pressure is supplied.
[0008]
The control valve 12 is a device that controls the supply of hydraulic pressure to the hydraulic chambers 11a and 11b, and moves to the left and right in FIG. 1 in conjunction with the steering force applied to the steering wheel 10 by the driver. In FIG. 1, when a steering force in the clockwise direction is applied, the control valve 12 also moves in the right direction in the drawing to guide the hydraulic pressure to one hydraulic chamber 11a. As a result, the piston 11c is pushed leftward in FIG. 1, and a steering assist force in the rightward direction is generated. Similarly, when a steering force in the left rotation direction is applied to the steering wheel 10, the control valve 12 also moves in the left direction in FIG. 1 and guides the hydraulic pressure to the other hydraulic chamber 11b, so that the piston 11c is in FIG. The steering assist force in the left direction is generated by being pushed in the right direction. Note that when the steering force from the driver is not applied to the steering wheel 10, the control valve 12 is in the neutral position, and thus no steering assist force is generated in any direction.
[0009]
Further, between the hydraulic pipe (high-pressure pipe) 22 connecting the oil pump 13 and the control valve 12 and the hydraulic pipe (low-pressure pipe) 23 connecting the control valve 12 and the oil tank 14, A bypass pipe 24 for returning a part to the oil tank 14 is provided. A linear solenoid valve 15 is provided in the middle of the bypass pipe 24 to continuously change the opening according to the magnitude of a control current from an ECU (electronic control unit) 2 described later. The ECU 2 controls the linear solenoid valve 15 according to the driving state of the vehicle such as the vehicle speed. For example, as the vehicle speed increases, the opening degree of the linear solenoid valve 15 increases and the hydraulic pressure to the hydraulic cylinder 11 decreases. The steering assist force is reduced.
[0010]
A hydraulic sensor (power steering hydraulic pressure detection means) 16 is provided in the middle of the hydraulic piping 22. The hydraulic pressure sensor 16 generates a signal corresponding to the magnitude of the steering assist force generation hydraulic pressure (power steering hydraulic pressure) supplied to the hydraulic cylinder 11 and outputs the signal to the ECU 2. The ECU 2 is a device that comprehensively controls the driving state of the vehicle, and controls the steering assist force of the power steering as described above, and also functions as an engine output control device that controls the output of the engine 1 based on various input information. is doing. In particular, the ECU 2 according to the present embodiment performs correction control of the engine output based on an input signal from the hydraulic sensor 16 representing the power steering load in order to prevent fluctuations in the engine rotation speed due to power steering load fluctuations. That is, the ECU 2 has a function as engine output correction means for correcting the output of the engine when the power steering load fluctuates.
[0011]
Hereinafter, engine output control (engine output correction control) for power steering load fluctuations by the ECU 2 will be described with reference to a flowchart shown in FIG.
First, in step S10, the ECU 2 detects the power steering oil pressure P _ps based on a signal (output voltage) from the oil pressure sensor 16. Specifically, the output characteristic of the hydraulic sensor 16 is linear with respect to the power steering oil pressure P _ps , and the ECU 2 uses a predetermined calculation formula or a map describing the relationship between the output of the hydraulic sensor 16 and the power steering oil pressure P _ps. The power steering hydraulic pressure P _ps is detected using (not shown).
[0012]
Next, in step 20, the ECU 2 sets a correction amount (first correction amount) Pepsb of the target torque Pe of the engine 1 corresponding to the detected power steering hydraulic pressure P _ps . Since the power steering hydraulic pressure P _ps represents the power steering load and the target torque Pe represents the output of the engine 1, the correction amount Pepsb of the target torque Pe is set according to the power steering hydraulic pressure P _ps in this way. Thus, output control of the engine 1 corresponding to a decrease in engine rotation speed due to application of a power steering load becomes possible. In ECU 2, using the map shown in FIG. 3, or, by a predetermined calculation formula, it is configuring the correction amount Pepsb corresponding to the detected power steering oil pressure P _ps.
[0013]
In step 30, the ECU 2 determines whether or not this time is the calculation time of the power steering hydraulic pressure change amount ΔP _ps that is performed every sampling number X of the power steering hydraulic pressure P _ps . If the determination condition in step S30 is satisfied, the process proceeds to step S40, and if not, the process proceeds to step S50. That is, the ECU 2 obtains a deviation between the power steering oil pressure P _ps (N) detected this time in step S10 and the power steering oil pressure P _ps (N−X) detected when the previous condition is satisfied at every sampling number X, and changes in the power steering oil pressure. The amount ΔP _ps [ΔP _ps = P _ps (N) −P _ps (N−X)] is calculated (step S40), and until the calculation time is reached, the power steering hydraulic pressure change amount ΔP _ps calculated when the previous condition is satisfied is calculated. Is held (step S50). However, when the deviation between P _ps (N) and P _ps (N−X) is 0 or less, the power steering hydraulic pressure change amount ΔP _ps is set to zero.
[0014]
As a specific example, when the power steering oil pressure P _ps shows a change as shown in FIG. 5A, when the power steering oil pressure change amount ΔP _ps is detected at every calculation (that is, when X = 1), The power steering hydraulic pressure change amount ΔP _ps changes in a waveform as shown in FIG. When the power steering hydraulic pressure change amount ΔP _ps is calculated every five samplings (that is, when X = 5), the power steering hydraulic pressure change amount ΔP _ps changes in a waveform as shown in FIG. Will do. The calculation load on the ECU 2 is reduced as the number of sampling times X is increased. However, as shown in FIGS. 5B and 5D, the waveform shape of the power steering hydraulic pressure change amount ΔP _ps is increased by setting the number of sampling times X. The setting of the correction amount (second correction amount) Pepsd corresponding to the power steering oil pressure change amount ΔP _ps, which will be described later, also changes (see FIGS. 5C and 5E). Therefore, it is preferable to set the sampling number X in consideration of the calculation load of the ECU 2 and the accuracy of control.
[0015]
At step S60, ECU 2 by matching the power steering oil pressure variation [Delta] P _ps obtained in step S40 or step S50 to the map as shown in FIG. 4, or by a predetermined calculation formula, the power steering hydraulic variation [Delta] P _ps The basic correction amount (basic second correction amount) Pepsd0 (N) of the target torque Pe corresponding to is calculated. In step S70, the ECU 2 determines whether or not the following condition is satisfied. (1) Is the power steering hydraulic pressure change ΔP _ps equal to or greater than a predetermined threshold A?
(2) Whether the basic correction amount Pepsd0 (N) calculated this time is greater than or equal to the previous final correction amount Pepsd (N-1).
[0016]
If both of the above conditions (1) and (2) are satisfied, the process proceeds to step S80, where the ECU 2 uses the basic correction amount Pepsd0 (N) calculated in step S60 as the fixed correction amount Pepsd (N ). On the other hand, when either of the above conditions (1) and (2) is not satisfied , the process proceeds to step S71, and in step S71, the ECU 2 determines whether or not the above condition (1) is satisfied again. To do. When the above condition (1) is satisfied , the process proceeds to step S90, where the ECU 2 determines the value obtained by subtracting the predetermined value B from the fixed correction amount Pepsd (N-1) set in the previous control cycle in the current control cycle. It is set as the correction amount Pepsd (N). However, when the value obtained by subtracting the predetermined value B from the fixed correction amount Pepsd (N−1) becomes 0 or less, the fixed correction amount Pepsd (N) is set to zero.
[0017]
As a specific example, when the power steering oil pressure change amount ΔP _ps changes in a waveform as shown in FIG. 5B (when X = 1), the correction amount (determined correction amount) Pepsd is shown in FIG. When the power steering oil pressure change amount ΔP _ps changes with the waveform shown in FIG. 5D (when X = 5), the correction amount Pepsd is set in FIG. 5E. It is set to change with the waveform as shown in FIG.
[0018]
The condition (1) defines a dead zone for the power steering hydraulic pressure change amount ΔP _ps , and when the power steering hydraulic pressure change amount ΔP _ps is within a range from 0 to the threshold A, the correction amount Pepsd Will be set to zero. That is, in step S71, when only the above condition (1) is not satisfied and when both of the above conditions (1) and (2) are not satisfied, the process proceeds to step S91, and the correction amount P epsd is set to 0. If the above condition (2) is not satisfied, the process proceeds to step S90, and the correction amount P epsd is set to a value obtained by subtracting the predetermined value B from the final correction amount P epsd set in the previous control cycle. become. The above threshold A is set within a limit where the power steering hydraulic pressure change amount ΔP _ps does not greatly affect the engine rotation speed. Therefore, even if the correction amount Pepsd is set to 0 within this range, the engine rotation speed fluctuates. On the contrary, by providing such a dead zone region, it is possible to prevent control flapping.
[0019]
Further, the above condition (2) indicates whether or not the power steering oil pressure change amount ΔP _ps is in an increasing process. That is, as shown in FIG. 4, the basic correction amount Pepsd0 is set larger as the power steering hydraulic pressure change amount ΔP _ps becomes larger. Therefore, when the basic correction amount Pepsd0 is larger than the previous final correction amount, the power steering hydraulic pressure change amount ΔP _ps is Thus, when the power steering oil pressure change amount ΔP _ps is increasing, the correction amount Pepsd corresponding to the power steering oil pressure change amount ΔP _ps is set. When the power steering oil pressure variation [Delta] P _ps is reduced, i.e., since the power steering hydraulic variation [Delta] P _ps peaked, the correction amount Pepsd would gradually be tailing to 0 at a constant gradient.
[0020]
The load fluctuation of the power steering is represented by a power steering hydraulic variation [Delta] P _ps, by setting the correction amount Pepsd of thus in conjunction with the increase in the power steering hydraulic variation [Delta] P _ps and the target torque Pe, the power steering load change It is possible to prevent the accompanying fluctuations in engine speed (decrease in engine speed). Also, when the power steering hydraulic variation [Delta] P _ps is reduced by the correction amount Pepsd rather than decrease rapidly in conjunction to power steering hydraulic variation [Delta] P _ps and go by tailing at a constant gradient, the correction amount Pepsd It is also possible to prevent the engine output from fluctuating due to a sudden change in.
[0021]
Next, in step S100, the ECU 2 sums the correction amount (first correction amount) Pepsb set in step S20 and the correction amount (second correction amount) Pepsd set in step S80 , step S90 or step S91. Peps = Pepsb + Pepsd) is obtained and compared with a predetermined value Pepsmax. The predetermined value Pepsmax is the maximum limit value of the total correction amount (power steering correspondence correction amount) Pepsc of the target torque Pe. If Peps is smaller than the maximum limit value Pepsmax, the process proceeds to step S110, and the ECU 2 sets the target torque Pe. The total correction amount (power steering correspondence correction amount) Pepsc is set to the sum of the correction amount Pepsb and the correction amount Pepsd. On the other hand, if Peps is larger than the maximum limit value Pepsmax, the process proceeds to step S120, and the ECU 2 sets the total correction amount Pepsc to the maximum limit value Pepsmax. In this manner, the maximum correction value Pepsmax is provided in the total correction amount Pepsc of the target torque Pe, thereby preventing excessive correction of the engine output.
[0022]
In step S130, the ECU 2 corrects the engine output based on the total correction amount Pepsc of the target torque Pe set in step S110 or step S120. Specifically, when the engine 1 is a general MPI (multi-point injection) engine, the engine output is corrected by controlling the throttle valve or bypass air valve (not shown) to adjust the intake air amount. Further, when the engine 1 is a cylinder injection engine, the ignition timing and the fuel injection timing can be adjusted in addition to the intake air amount, so that the engine output can be corrected more finely.
[0023]
As described above, in the present embodiment, the ECU 2 functions as an engine output correction unit and also functions as a hydraulic pressure change detection unit according to the present invention together with the hydraulic sensor 16. The ECU 2 includes an input / output device (not shown), a storage device (ROM, RAM, etc.) used for storing control programs and control maps, a central processing unit (CPU), a timer counter, and the like. The above functions are realized by cooperation.
[0024]
Next, the effect | action by the engine output control concerning this embodiment and its effect are demonstrated with reference to the specific example shown in FIG. Here, it is assumed that the output value of the hydraulic sensor 16 has changed as shown in FIG. The ECU 2 detects the power steering oil pressure P _ps from the output signal of the oil pressure sensor 16 and sets the first correction amount Pepsb. The waveform of the first correction amount Pepsb substantially coincides with the waveform of the output signal of the hydraulic sensor 16, that is, the waveform of the power steering oil pressure, as shown by a one-dot chain line in FIG.
[0025]
Further, the ECU 2 detects the detected change amount ΔP _ps of the power steering hydraulic pressure P _ps at every predetermined period to set the second correction amount Pepsd. The second correction amount Pepsd is set on the condition that the power steering oil pressure change amount ΔP _ps becomes equal to or greater than the threshold A as shown in FIG. 6C (time t ₁₀ , t ₂₀ ), and the power steering oil pressure change amount ΔP _ps. Until reaching the peak value (until times t ₁₁ and t ₂₁ ), the magnitude is set according to the power steering hydraulic pressure change amount ΔP _ps . Then, after the power steering hydraulic pressure change amount ΔP _ps reaches the peak value, tailing is performed to 0 with a constant gradient. The ECU 2 adds the first correction amount Pepsb and the second correction amount Pepsd set in this way (indicated by a thin solid line in FIG. 6 (d)), and limits the maximum value to the maximum limit value Pepsmax. The total correction amount Pepsc is set (indicated by a thick solid line in FIG. 6D).
[0026]
Thus, according to the engine output control according to the present embodiment, since the power steering oil pressure P _ps to the engine output corresponding to the variation in the power steering hydraulic P _ps by the setting of the first correction amount Pepsb corresponding correction is possible, It is possible to prevent fluctuations in the engine speed due to the input of the power steering load. Furthermore, even when the power steering load is suddenly input, the engine output in accordance with the power steering hydraulic variation [Delta] P _ps by the addition of the second correction amount Pepsd is increased corrected, the variation of the engine rotational speed even when such It can be surely prevented. Further, since the correction amount of the engine output at this time corresponds to the power steering hydraulic pressure change amount ΔP _ps , the engine output is not increased more than necessary, and unnecessary fuel consumption is not caused.
[0027]
That is, according to the engine output control according to the present embodiment, the first correction amount Pepsb corresponding to the power steering oil pressure P _ps and the second correction amount Pepsd corresponding to the power steering oil pressure change amount ΔP _ps are added and the total correction amount Pepsc is added. Since the engine output is corrected based on the total correction amount Pepsc, the engine output can be corrected accurately and quickly in response to both the load caused by power steering and its fluctuation, and wasteful fuel consumption is suppressed. However, there is an effect that it is possible to reliably prevent fluctuations in the engine rotational speed due to power steering load fluctuations.
[0028]
Furthermore, according to the engine output control according to the present embodiment, since the total correction amount Pepsc is limited to the maximum limit value Pepsmax, it is possible to prevent fluctuations in the engine speed due to overcorrection. Further, after the power steering oil pressure change amount ΔP _ps reaches the peak value, the second correction amount Pepsd is tailed to 0 with a constant gradient rather than corresponding to the power steering oil pressure change amount ΔP _ps. The engine speed does not decrease due to sudden changes (rapid decrease).
[0029]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, after the power steering oil pressure change amount ΔP _ps reaches the peak value, the second correction amount Pepsd is tailed with a constant gradient, but the tailing speed is not necessarily constant. Alternatively, it can be made variable according to conditions.
[0030]
【The invention's effect】
As described above in detail, according to the engine output control device of the present invention, the first correction amount that increases in proportion to the increase in the hydraulic pressure detected by the power steering hydraulic pressure detection means and the hydraulic pressure change detected by the hydraulic pressure change detection means. Since the engine output is corrected based on the power steering correspondence correction amount calculated by adding the second correction amount that increases in proportion to the increase in the amount, it can be accurately and quickly adapted to both the load caused by power steering and its fluctuations. Further, the engine output can be corrected, and there is an effect that the fluctuation of the engine rotation speed accompanying the fluctuation of the power steering load can be surely prevented while suppressing wasteful fuel consumption.
Further, since when the hydraulic change amount changes in the decreasing direction reaches the peak value gradually decreases the second correction amount gradually, it is possible to prevent the engine rotational speed decreases by a rapid decrease correction of the engine output effect There is.
[0031]
Further , when the power steering correspondence correction amount is limited to the maximum correction amount when the power steering correspondence correction amount is equal to or greater than a predetermined maximum correction amount, there is an effect of preventing fluctuations in the engine rotation speed due to excessive correction .
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a vehicle according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a flow of engine output control according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating a control map according to an embodiment of the present invention, and is a diagram illustrating a setting characteristic of a first correction amount with respect to a power steering hydraulic pressure.
FIG. 4 is a diagram showing a control map according to an embodiment of the present invention, and is a diagram showing a setting characteristic of a basic second correction amount with respect to a power steering hydraulic pressure change amount.
FIGS. 5A and 5B are diagrams for explaining a method of setting a second correction amount according to an embodiment of the present invention, where FIG. 5A is a diagram showing a change in power steering oil pressure, and FIG. The figure which shows the change of the power steering oil pressure change amount in a case, (c) is a figure which shows the setting of the 2nd correction amount corresponding to (b), (d) is the change of the power steering oil pressure change amount when it samples every 5 periods. (E) is a figure which shows the setting of the 2nd correction amount corresponding to (d).
6A and 6B are diagrams showing a specific example of setting a power steering correspondence correction amount according to an embodiment of the present invention, in which FIG. 6A is a diagram showing a change in power steering hydraulic pressure, and FIG. The figure which shows the change of oil pressure change amount, (c) is a figure which shows the setting of the 2nd correction amount corresponding to (b), (d) is the 1st correction amount (one-dot chain line) corresponding to (a), It is a figure which shows the setting of the addition value (thin solid line) of 1 correction amount and 2nd correction amount, and final correction amount (thick solid line).
[Explanation of symbols]
1 Engine 2 ECU (Engine Output Control Device)
3 Power steering system (power steering)
10 Steering wheel 11 Hydraulic cylinder 12 Control valve 13 Oil pump 16 Hydraulic sensor

Claims (2)

A power steering hydraulic pressure detecting means for detecting a hydraulic pressure for generating a steering assist force of the power steering;
Oil pressure change amount detecting means for detecting the oil pressure change amount;
A first correction amount that increases in proportion to the increase in oil pressure detected by the power steering oil pressure detection means and a second correction amount that increases in proportion to the increase in oil pressure change detected by the oil pressure change amount detection means. Engine output correction means for correcting the engine output based on the power steering correspondence correction amount calculated by adding,
The engine output correcting means, when said hydraulic pressure change amount changes in the decreasing direction reaches the peak value, characterized in that it is configured to gradually reduce the second correction amount gradually, the engine output control apparatus. The engine output correction means is configured to limit the power steering correspondence correction amount to the maximum correction amount when the power steering correspondence correction amount is equal to or greater than a predetermined maximum correction amount. Engine output control device.

Images