JP2016108977A - Control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device capable of suppressing overheat or failure of a motor while switching the lift amounts of a suction valve and exhaust valve of an internal combustion engine by controlling a motor having small output.SOLUTION: A lift amount switching unit 213 drives a motor 15 when the operation state of an internal combustion engine 100 becomes a predetermined condition, and switches between a first state where the lift amounts of a suction valve and exhaust valve are defined as VM, and a second state where the lift amounts of the suction valve and exhaust valve are defined as VH larger than VM. When switching frequency of the first state and the second state is in a high frequency state where it becomes more than or equal to a predetermined value, the lift amount switching unit stops switching between the first state and the second state.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control device that controls a motor and switches lift amounts of an intake valve and an exhaust valve of an internal combustion engine by driving the motor.

  2. Description of the Related Art In an internal combustion engine mounted on a vehicle, one that switches intake and exhaust characteristics according to the operating state of the internal combustion engine is known. Specifically, the lift amount of the intake valve and the exhaust valve provided in the cylinder of the internal combustion engine is switched so as to be suitable for the operation state of the internal combustion engine at that time.

  Patent Document 1 below describes a control device that displaces a control member using a motor and a cam and performs the switching by the action of the control member. The cam that rotates as the motor is driven is configured to bring the control member into contact with the outer peripheral surface thereof. The control member abuts the outer peripheral surface of the cam at one end, and the other end extends to the internal combustion engine.

  The cam is formed such that the distance from the rotation center to the outer peripheral surface varies depending on the portion of the outer peripheral surface. For this reason, when the contact part of a control member and a cam changes with rotation of a cam, a control member is comprised so that it may displace.

  A plurality of stationary portions (step portions) are formed on the outer peripheral surface of the cam. This stationary part is formed so that the inclination of the displacement amount of the control member accompanying the rotation of the cam is different from other parts. The control device disclosed in Patent Document 1 is configured to switch the position of the control member by setting the control member in contact with any one of the plurality of stationary portions.

  The control member can switch the lift amount of the intake valve and the exhaust valve to be suitable for the operating state of the internal combustion engine at that time by switching the position as appropriate. Thereby, the output improvement of an internal combustion engine, a fuel consumption reduction, etc. can be aimed at.

JP 2014-119087 A

  In such an internal combustion engine, in order to reduce the size of the apparatus and to suppress the manufacturing cost, it is required to employ a motor having the smallest possible maximum output as the motor for switching the lift amount. For this reason, when switching the lift amount, it is required to drive the motor in the vicinity of the maximum duty.

  In such a configuration, if the lift amount is frequently switched, an excessive load may be applied to the motor. As a result, the motor may overheat and cause a failure.

  The present invention has been made in view of such problems, and the object of the present invention is to control a motor with a small output to switch the lift amount of an intake valve and an exhaust valve of an internal combustion engine, while overheating the motor. An object of the present invention is to provide a control device capable of suppressing failure.

  In order to solve the above-described problems, the control device according to the present invention controls the motor (15) and drives the motor to control the lift amounts (VL, VM, VH) of the intake valve and the exhaust valve of the internal combustion engine (100). A control device (21) for switching, the power supply means (212) for supplying power to the motor, and the motor when the operating state of the internal combustion engine becomes a predetermined condition, the lift amount of the intake valve and the exhaust valve Lift amount switching for switching between a first state in which the lift amount (VM) is the first lift amount (VM) and a second state in which the lift amount of the intake valve and the exhaust valve is a second lift amount (VH) greater than the first lift amount Means (213) and switching frequency detecting means (214) for detecting the frequency of switching between the first state and the second state, and the lift amount switching means is for switching between the first state and the second state. Frequent If is became frequent state is a condition that more than a predetermined value, stops the first state and switching between the second state.

In the control device according to the present invention, when the frequency of switching between the first state and the second state becomes a high frequency state in which the frequency is a predetermined value or more, switching between the first state and the second state is performed. Stop.
For this reason, when the switching of the switching between the first state and the second state becomes frequent, the switching can be stopped, and it is possible to suppress further load on the motor. Therefore, it is possible to suppress overheating and failure of the motor.

  According to the present invention, there is provided a control device capable of suppressing overheating and failure of a motor while switching a lift amount of an intake valve and an exhaust valve of an internal combustion engine by controlling a motor having a small output.

1 is a schematic configuration diagram of a valve control system to which a control device according to an embodiment of the present invention is applied. It is a figure which shows schematic structure of a cam and a control shaft. It is a control block diagram for demonstrating the functional block of a control apparatus. It is a figure which shows the 1st map showing the relationship between the driving | running state of an internal combustion engine, and lift amount. It is a flowchart which shows the control by the control apparatus which concerns on embodiment of this invention. It is a figure which shows the relationship between the rotation angle of a cam, and the electric current supplied to the motor. It is a figure which shows the 2nd map showing the relationship between the driving | running state of an internal combustion engine, and lift amount. It is a figure which shows the relationship between a crank angle and valve lift amount.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  First, an overview of a control device 21 according to an embodiment of the present invention and a valve control system 11 to which the control device 21 is applied will be described with reference to FIGS. 1 to 3. The valve control system 11 is a system that controls an intake valve and an exhaust valve of the internal combustion engine 100 mounted on the vehicle. The valve control system 11 includes a control shaft 12, an actuator unit 13, and a valve opening / closing characteristic changing mechanism 14.

  As shown in FIG. 1, the control shaft 12 is a rod-shaped member that is displaced by sliding in the axial direction. One end 12a of the control shaft 12 is provided on the actuator unit 13 side, and the other end 12b is provided on the valve opening / closing characteristic changing mechanism 14 side.

  The actuator unit 13 is a mechanism that applies an axial force to the control shaft 12 to displace the control shaft 12. The actuator unit 13 includes a motor 15, a speed reducer 16, a cam 17, and a rotation angle sensor 19.

  The motor 15 is a prime mover that is driven to rotate by receiving electric power to generate torque. The output shaft of the motor 15 is connected to the speed reducer 16. Torque generated by the motor 15 is transmitted to the cam 17 via the speed reducer 16.

  As shown in FIG. 2, the cam 17 is configured to rotate around the rotation center RC when torque is transmitted from the speed reducer 16 as the motor 15 rotates. The outer peripheral surface 17a of the cam 17 is formed as a curved surface. The cams 17 are formed such that the distance from the rotation center RC to the outer peripheral surface 17a is different depending on the portion of the outer peripheral surface 17a.

  A first stationary part LP, a second stationary part MP, and a third stationary part HP are formed on the outer peripheral surface 17a of the cam 17 at intervals. Among these, the 1st stationary part LP is a site | part with the shortest distance from the rotation center RC. The third stationary part HP is a part having the longest distance from the rotation center RC. That is, the distance from the rotation center RC is configured to increase in three stages from the first stationary part LP to the third stationary part HP through the second stationary part MP. In FIG. 2, for convenience of explanation, the first stationary part LP, the second stationary part MP, and the third stationary part HP are indicated by bold lines. One end 12 a of the control shaft 12 is in contact with the outer peripheral surface 17 a of the cam 17.

  The rotation angle sensor 19 is a sensor that is disposed in the vicinity of the cam 17 and outputs a signal according to the rotation angle from the reference position of the cam 17. A signal output from the rotation angle sensor 19 is input to the control device 21 (see FIG. 1) via a signal line.

  The valve opening / closing characteristic changing mechanism 14 is attached to the internal combustion engine 100. The valve opening / closing characteristic changing mechanism 14 is a mechanism for switching the intake and exhaust characteristics of the internal combustion engine 100 by changing the opening / closing characteristics of the intake valve and the exhaust valve. Specifically, the valve opening / closing characteristic changing mechanism 14 changes the maximum lift amount and operating angle of the intake valve and the exhaust valve of the internal combustion engine 100. The other end 12 b of the control shaft 12 is connected to the valve opening / closing characteristic changing mechanism 14.

  The control device 21 controls the valve control system 11 as described above. The control device 21 is electrically connected to the motor 15 and the rotation angle sensor 19, and receives a signal to perform processing or supply power.

  A part or all of the control device 21 is configured by an analog circuit or a digital processor provided with a memory. In any case, a functional control block is configured in the control device 21 in order to fulfill the function of outputting a control signal based on the received signal. FIG. 3 shows the control device 21 as such a functional control block diagram. It should be noted that the software module incorporated in the analog circuit or digital processor constituting the control device 21 does not necessarily have to be divided like the control block shown in FIG. That is, it may be configured to function as a plurality of control blocks, or may be further subdivided. If the control device 21 is configured to execute a processing flow described later, the actual configuration inside the control device 21 can be appropriately changed by those skilled in the art.

  As shown in FIG. 3, the control device 21 includes a rotation angle detection unit 211, a power supply unit 212 (power supply unit), a lift amount switching unit 213 (lift amount switching unit) as functional control blocks. , A switching frequency detection unit 214 (switching frequency detection unit), a timing change unit 215 (timing change unit), and a storage unit 216.

  The rotation angle detection unit 211 is a part that processes a signal received from the rotation angle sensor 19. The rotation angle detector 211 detects the rotation angle of the cam 17 by this processing.

  The power supply unit 212 is a part that supplies driving power to the motor 15 of the actuator unit 13. Specifically, the power supply unit 212 supplies the electric power stored in a battery (not shown) to the motor 15 while adjusting the supply amount so that the rotation angle of the cam 17 matches the target value.

  The lift amount switching unit 213 is a portion that switches the lift amounts of the intake valve and the exhaust valve of the internal combustion engine 100. As will be described later, the lift amount switching unit 213 switches the lift amount by displacing the control shaft 12.

  The switching frequency detection unit 214 is a part that detects the switching frequency of the lift amount by the lift amount switching unit 213. Specifically, the switching frequency detection unit 214 detects the frequency at which the switching frequency detection unit 214 switches the lift amounts of the intake valve and the exhaust valve of the internal combustion engine 100 during a predetermined period.

  The timing changing unit 215 is a part that changes the valve timing of the intake valve and the exhaust valve of the internal combustion engine 100. Specifically, the timing changing unit 215 changes the timing at which the intake valve and the exhaust valve of the internal combustion engine 100 are opened and closed.

  The storage unit 216 is a part that writes various data used for control processing in the control device 21 and enables reading of the data. Specifically, a map or the like to be described later is written in the storage unit 216 and can be read by the power supply unit 212 or the like.

  Hereinafter, for the sake of simplicity, the processing performed by each block such as the rotation angle detection unit 211 of the control device 21 will be described as being performed by the control device 21 as a whole.

  When the control device 21 determines from the signal received from the rotation angle sensor 19 that there is a difference between the rotation angle of the cam 17 and the target value, the control device 21 supplies electric power to the motor 15 so that the rotation angle matches the target value. Start supplying. The motor 15 is rotationally driven according to the supplied electric energy, and the cam 17 is also rotated accordingly.

  Of the outer peripheral surface 17 a of the cam 17, the portion with which the one end 12 a of the control shaft 12 abuts changes as the cam 17 rotates. Furthermore, the distance from the rotation center RC of the cam 17 to the one end 12a changes as the contact portion between the outer peripheral surface 17a and the one end 12a changes. Thereby, the control shaft 12 is displaced so as to reciprocate in the axial direction.

  Here, the rotation angle of the cam 17 and the displacement of the control shaft 12 are uniquely related. For this reason, the position of the control shaft 12 can be converged to the target position by performing feedback control in which the detected value of the rotation angle of the cam 17 by the rotation angle sensor 19 matches the target value.

  Further, the first stationary part LP, the second stationary part MP, and the third stationary part HP of the outer peripheral surface 17a described above are formed so as not to displace the control shaft 12 when the cam 17 rotates. That is, the first stationary part LP, the second stationary part MP, and the third stationary part HP are all formed in an arc shape having a constant radius, and when the one end 12a of the control shaft 12 passes through them, it rotates. The distance from the center RC to the one end 12a is not changed. Therefore, only when the one end 12a is in contact with the first stationary part LP, the second stationary part MP, or the third stationary part HP, the control shaft 12 remains stationary without being displaced even when the cam 17 rotates. It becomes.

  The internal combustion engine 100 receives different actions depending on the position of the control shaft 12. When the one end 12a of the control shaft 12 is in contact with the first stationary portion LP of the outer peripheral surface 17a of the cam 17, the lift amounts of the intake valve and the exhaust valve of the internal combustion engine 100 are VL. On the other hand, when the one end 12a of the control shaft 12 is in contact with the third stationary portion HP of the outer peripheral surface 17a of the cam 17, the lift amounts of the intake valve and the exhaust valve of the internal combustion engine 100 become VH larger than VL. . When the one end 12a of the control shaft 12 is in contact with the second stationary portion MP of the outer peripheral surface 17a of the cam 17, the lift amounts of the intake valve and the exhaust valve of the internal combustion engine 100 are larger than VL and larger than VH. It becomes a small VM. That is, the control device 21 switches the lift amount of the intake valve and the exhaust valve to VL by switching the position where the control shaft 12 contacts to one of the first stationary part LP, the second stationary part MP, and the third stationary part HP. , VM, and VH.

  Next, switching of the lift amounts VL, VM, VH of the intake valve and the exhaust valve of the internal combustion engine 100 in the valve control system 11 configured as described above will be described with reference to FIG.

  The control device 21 stores a first map as shown in FIG. 4 in the storage unit 216. The control device 21 switches the lift amounts of the intake valve and the exhaust valve of the internal combustion engine 100 based on the first map.

  In this first map, the operating state of the internal combustion engine 100 is divided into three according to the combination of the load and the rotational speed. In the first map, lift amounts VL, VM, and VH of the intake valve and the exhaust valve are assigned to the three operating states of the internal combustion engine 100, respectively.

  Specifically, in the first map, when the internal combustion engine 100 is in a low load and low speed operation state, VL is assigned to the lift amounts of the intake valve and the exhaust valve. Further, when the operating state to which the lift amount VL is assigned changes to the operating state (first state) in which at least one of the load and the rotational speed of the internal combustion engine 100 is large, the lift amount of the intake valve and the exhaust valve is set to VM. (First lift amount) is assigned. Further, when at least one of the load and the rotational speed of the internal combustion engine 100 is changed from the operation state to which the lift amount VM is assigned to the operation state (second state), the lift amount of the intake valve and the exhaust valve is reduced to VH. Is assigned. As described above, VM is larger than VL and VH is larger than VM.

  The control device 21 determines the lift amount of the intake valve and the exhaust valve by switching the load and the rotational speed of the internal combustion engine 100 at that time with the first map, and performs switching. That is, the control device 21 determines which of the three sections of the first map the operating state of the internal combustion engine 100 at that time belongs to, and sets the lift amounts of the intake valve and the exhaust valve to the sections. Switch to the assigned lift amount.

  The control device 21 compares the load and the rotational speed of the internal combustion engine 100 with the first map at any time or periodically. The control device 21 does not change the lift amounts of the intake valve and the exhaust valve when there is no change in the section to which the operating state of the internal combustion engine 100 belongs before and after the comparison. The control device 21 displaces the control shaft 12 as described above when there is a change in the section to which the operating state of the internal combustion engine 100 belongs before and after the comparison. Then, the control device 21 switches the lift amount of the intake valve and the exhaust valve to any one of VL, VM, and VH assigned to the newly belonging section.

  By the way, when the lift amounts VL, VM, VH of the intake valve and the exhaust valve are switched, the control device 21 rotates the motor 15 to displace the control shaft 12. There is a demand for the motor 15 to have a maximum output as small as possible in order to reduce the size of the apparatus and reduce the manufacturing cost. For this reason, when the lift amounts VL, VM, and VH are switched, it is required to drive the motor 15 in the vicinity of the maximum duty.

  In such a configuration, if the lift amounts VL, VM, and VH are frequently switched, an excessive load may be applied to the motor 15. For this reason, the motor 15 may be overheated, resulting in a failure.

  Therefore, in the control device 21 according to the present embodiment, in a situation where the motor 15 may be overheated, the control process is changed to solve this problem. Hereinafter, the control processing of the control device 21 will be described with reference to FIGS.

  First, as shown in FIG. 5, the control device 21 calculates the sum of the amount of electric power supplied to the motor 15 in a predetermined period T in step S <b> 1. The control device 21 moves the third stationary portion HP while moving the one end 12a of the control shaft 12 from the first stationary portion LP to the second stationary portion MP and from the second stationary portion MP to the third stationary portion HP. To the first stationary part LP, electric power is supplied to the motor 15 in each of them. In step S1, the sum of the amounts of power supplied to the motor 15 in the predetermined period T is calculated.

  Here, the sum of the amount of power supplied to the motor 15 in the predetermined period T can be calculated from the current and voltage supplied to the motor 15. As shown in the upper part of FIG. 6, the motor 15 is adjusted so that the detected value (solid line) of the rotation angle of the cam 17 by the rotation angle sensor 19 matches the target value (broken line) that changes between θL and θM. During the driving, the value of the current supplied to the motor 15 shows a change as shown in the lower part of FIG. Among these, a period (from time t1 to time t2, from time t3 to time t4, from time t5 to time t6, from time t7 to time t8, from when the detection value by the rotation angle sensor 19 starts to change and coincides with the target value. In each period), the product of the areas S1, S2, S3, S4 shown in the lower part of FIG. 6 and the voltage supplied to the motor 15 is the amount of electric power supplied to the motor 15. In step S1, these sums are calculated. calculate.

  Next, in step S2 shown in FIG. 5, the control device 21 determines whether or not the calculated sum of electric energy is equal to or greater than a threshold value. The sum of the electric energy calculated in step S1 has a proportional correlation with the switching frequency of the lift amounts VL, VM, VH of the intake valve and the exhaust valve described above. The more frequently the lifts VL, VM, and VH are switched, the more frequently the motor 15 needs to be rotationally driven. Therefore, the sum of the amounts of power supplied to the motor 15 in the predetermined period T increases.

  Therefore, if it is determined in step S2 shown in FIG. 5 that the calculated sum of electric energy is equal to or greater than the threshold (step S2: Yes), the motor 15 is rotationally driven at a high frequency and may be overheated. Can be estimated. In this case, the control device 21 then proceeds to step S3.

  Next, the control device 21 performs map switching in step S3. The map switching will be described in detail. First, the storage unit 216 of the control device 21 stores a second map shown in FIG. 7 in addition to the first map (see FIG. 4) described above.

  In the second map, as in the first map, the operating state of the internal combustion engine 100 is divided using the load and the rotational speed of the internal combustion engine 100 as indices. However, the operation state of the internal combustion engine 100 is divided into three in the first map, whereas the operation state of the internal combustion engine 100 is divided into two in the second map. That is, in the first map, the operating state of the internal combustion engine 100 is divided into three that can be assigned lift amounts VL, VM, and VH, whereas in the second map, each of the lift amounts VL and VM is assigned. It is divided into two to be assigned.

  In step S3, the control device 21 changes the control process so that the lift amounts VL and VM of the intake valve and the exhaust valve are switched using the second map instead of the first map used so far. Thus, when the first map is used, even when the internal combustion engine 100 is switched with the lift amounts VM and VH, the lift amount remains constant at the lift amount VM after switching to the second map. Will remain. That is, the switching frequency of the lift amount can be reduced.

  Next, in step S4, the control device 21 selects a valve timing correction amount. That is, when the lift amount of the intake valve and the exhaust valve is set to VL, the correction amount of the valve timing is unchanged at 10 [deg−CA] regardless of which of the first map and the second map is used. However, in the first map, in the operating state of the internal combustion engine 100 where the lift amount of the intake valve and the exhaust valve is VM, the correction amount is 20 [deg−CA], whereas the correction amount is 20%. The correction amount is 30 [deg-CA]. Further, in the first map, in the operating state of the internal combustion engine 100 where the lift amount of the intake valve and the exhaust valve is VH, the correction amount is 30 [deg−CA], whereas the correction amount is 30 °. The correction amount is 50 [deg-CA].

  Accordingly, as shown in FIG. 8, the valve timing correction amount when the first map is used is θ1 [deg−CA], whereas the valve timing when the second map is used. The amount of timing correction is θ2 [deg−CA], which is larger than when the first map is used.

  As described above, in the control device 21 according to the present embodiment, when the frequency of switching the lift amount of the intake valve and the exhaust valve of the internal combustion engine 100 becomes a high frequency state in which the frequency is equal to or higher than the threshold value. , The switching is stopped. For this reason, when the switching of the lift amount becomes frequent, the switching can be stopped, and it is possible to prevent the motor 15 from being further loaded. Therefore, overheating and failure of the motor 15 can be suppressed.

  The lift amount switching unit 213 of the control device 21 switches the lift amounts of the intake valve and the exhaust valve of the internal combustion engine 100 when the total amount of electric power supplied to the motor 15 exceeds the predetermined amount during the predetermined period T. Stop. That is, it is possible to easily estimate from the amount of power supplied to the motor 15 that the motor 15 is in danger of overheating or failure.

  In addition, the control device 21 includes a timing changing unit 215 that changes the valve timing of the intake valve and the exhaust valve, and the timing changing unit 215 stops the switching of the lift amounts of the intake valve and the exhaust valve of the internal combustion engine 100. Change the valve timing. Thereby, it becomes possible to suppress the influence on drivability by switching the lift amount of the intake valve and the exhaust valve.

  Further, the control device 21 has a higher frequency state in which the frequency of switching the lift amount of the intake valve and the exhaust valve of the internal combustion engine 100 is equal to or higher than a threshold value, compared to a case where the frequency is not a high frequency state. Increase the amount of change when changing the valve timing. Thereby, it becomes possible to further suppress the influence on drivability by switching the lift amount of the intake valve and the exhaust valve.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. Each element included in each of the specific examples described above and their arrangement, material, condition, shape, size, and the like are not limited to those illustrated, and can be appropriately changed.

15: Motor 21: Control device 100: Internal combustion engine 212: Power supply unit (power supply means)
213: Lift amount switching unit (lift amount switching means)
214: switching frequency detection unit (switching frequency detection means)
215: Timing changing unit (timing changing means)
VL, VM, VH: Lift amount

Claims (4)

A control device (21) for controlling a motor (15) and switching lift amounts (VL, VM, VH) of an intake valve and an exhaust valve of the internal combustion engine (100) by driving the motor,
Power supply means (212) for supplying power to the motor;
A first state in which when the operating state of the internal combustion engine becomes a predetermined condition, the motor is driven and the lift amount of the intake valve and the exhaust valve is set to a first lift amount (VM); Lift amount switching means (213) for switching between a second state in which the lift amount of the exhaust valve is set to a second lift amount (VH) larger than the first lift amount;
Switching frequency detection means (214) for detecting the frequency of switching between the first state and the second state,
When the lift amount switching means is in a high-frequency state in which the frequency of switching between the first state and the second state is equal to or higher than a predetermined value, the lift amount switching means The control apparatus characterized by stopping switching.   The lift amount switching means stops switching between the first state and the second state when the total amount of electric power supplied to the motor exceeds a predetermined amount during a predetermined period (T). The control device according to claim 1. Timing changing means (215) for changing valve timings of the intake valve and the exhaust valve;
The control device according to claim 2, wherein the timing changing unit changes the valve timing when switching between the first state and the second state is stopped.   4. The control device according to claim 3, wherein the amount of change when changing the valve timing is increased when the high-frequency state is reached, compared to when the high-frequency state is not set.

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