JP4315566B2 - Variable transmission ratio steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission ratio variable type steering apparatus in which a value of a steering wheel turning angle with respect to a steering angle of a steering wheel is changed according to a vehicle speed or the like, and in particular, a transmission ratio in such a steering apparatus. In the event that an abnormal situation occurs in the variable mechanism, the steering system is directly connected after adjusting the steering wheel so that the phase angle returns to the normal neutral position when setting the transmission ratio to a fixed value. The present invention relates to a variable transmission ratio type steering apparatus.
[0002]
[Prior art]
In general, in an automobile steering device, during low-speed driving such as stationary steering, the steering wheel angle is made larger with respect to the steering wheel operation amount (steering angle), thereby facilitating steering operation. When driving at high speed, it is desired to reduce the value of the turning angle of the steered wheels with respect to the steering operation so as to improve the steering stability. From this point of view, a transmission ratio variable type steering device has been developed in which the transmission ratio in the steering system is changed according to the situation, and is already known, for example, from Japanese Patent Laid-Open No. 10-324263.
[0003]
[Problems to be solved by the invention]
By the way, in these, the transmission ratio variable mechanism for changing the transmission ratio between the steering wheel and the steering wheel is formed on the basis of a differential gear mechanism such as a planetary gear mechanism. The change of the transmission ratio is appropriately controlled by the operation of the electric motor that operates accordingly. In such a transmission ratio variable mechanism, when an abnormal situation such as overheating of the electric motor occurs, the operation of the transmission ratio variable mechanism is immediately locked and fixed so that the transmission ratio becomes a value of 1. The steering wheel and the steered wheel are connected so as to be in a direct connection state. Therefore, when the transmission wheels are forcibly connected so that the value of the transmission ratio is 1 as described above, the steering wheel phase is shifted from the normal neutral position when the steering wheel is in the straight traveling state. It may become. This gives an uncomfortable feeling to the driver (driver). In order to solve such problems, the overheating of the electric motor is predicted in advance, the transmission ratio variable mechanism is controlled so that the transmission ratio becomes 1 with a margin, and the steering wheel is in a straight traveling state during this period SUMMARY OF THE INVENTION It is an object (problem) of the present invention to provide a transmission ratio variable type steering device in which the neutral position of the steering wheel is returned to a state where there is no phase shift with respect to a normal state.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the following measures are taken in the present invention. That is, in the invention according to claim 1, transmission ratio variable means provided in the middle of the steering transmission system for connecting the steering handle and the steering wheel and operating to change the transmission ratio by driving the motor; Coupling means that operates to fix the transmission ratio between the input side and output side of the transmission ratio variable means according to the situation, and control means that controls the operation of the transmission ratio variable means and the coupling means, A transmission ratio variable steering means that operates when the control means determines the connection operation of the connection means and determines whether the transmission ratio is a value of 1 or not. And a transmission ratio return means for operating the motor so that the transmission ratio of the transmission ratio variable means becomes a value of 1 when the transmission ratio determined by the transmission ratio determination means is not a value of 1. , It is assumed that a connection permission unit that operates so as to permit the operation of the connection unit only when the transmission ratio is 1 is provided.
[0005]
By adopting such a configuration, in the present invention, the neutral position of the steering wheel coincides with the neutral position of the steering wheel in a state where the connecting means is operated and the steering handle and the steering wheel are connected. Will be. In other words, the neutral position of the steering wheel is not shifted (ie, a phase shift occurs) when the steering wheel is in the straight traveling state.
[0006]
Next, the invention described in claim 2 will be described. The basic point of this is the same as that of the first aspect. That is, according to the present invention, in the transmission ratio variable type steering apparatus according to claim 1, when the control means determines that there is a possibility that the operation of the motor is abnormal, the connection means is forcibly connected. It was decided to adopt a configuration that allowed them to do so. By adopting such a configuration, the steering system can be forcibly brought into a direct connection state in an emergency and the fail-safe function can be activated.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the present embodiment relates to a steering handle 2, a power steering device 3 for steering the steered wheels 9 to a predetermined turning angle according to the operation of the steering handle 2, and the power steering device 3 A transmission ratio variable means 1 which is provided between the steering wheel 2 and the steering wheel 2 and operates to change the transmission ratio of the steering amount (steering angle) between the steering wheel 2 and the steering wheel 9 as appropriate. It is based on that it consists of.
[0008]
In such a configuration, the transmission ratio variable means 1 provided between the steering handle 2 and the power steering device 3, specifically, in the middle of the steering shaft 21, includes various sensors as shown in FIG. 2. 16, 17, 18, 19, the operation unit 15 including the motor 151, and the operation of the operation unit 15 including the motor 151 based on signals from the various sensors 16, 17, 18, 19. And a control means 11 for controlling.
[0009]
Specifically, the various sensors are provided in the middle of the steering shaft 21, and the steering wheel steering angle sensor 18 that detects the rotation angle (steering angle) of the steering handle 2 and the motor 151 that drives the speed reduction mechanism 155. Motor temperature sensor 17 for detecting the temperature of the vehicle, vehicle speed sensor 19 for detecting the traveling speed of the vehicle, and steering wheel steering angle sensor 16 for detecting the turning angle of the steering wheel 9, that is, the steering angle of the steering wheel 9. . And each detection signal from each of these sensors 16, 17, 18, 19 is sent to the next control means 11 at any time.
[0010]
The control means 11 for receiving the signals from these various sensors and controlling the operation of the motor 151 or the like that forms the next operating unit 15 is composed of a microcomputer mainly composed of a microprocessor unit (MPU). In the present embodiment, the control means 11 is mainly provided with a calculation unit that performs various calculation processes including the determination of the transmission ratio, and in addition to these, the following functional unit is provided. Yes. That is, since the motor 151 is in an overheated state, when the transmission means variable means 1 is locked by operating the connecting means 152, it is determined whether the transmission ratio at that time is 1 or not. When the transmission ratio is determined to be a value other than 1 as a result of determination by the ratio determination unit 111 and the transmission ratio determination unit 111, the motor 151 is driven to return the transmission ratio to a value of 1. When the transmission ratio return means 112 that outputs (signal) and the transmission ratio determination means 111 determine that the transmission ratio is a value of 1, a command (signal) is issued to activate the next connecting means 152. In addition to the connection permission means 113, in addition to these, when the temperature of the motor 151 is in an overheated state, the rate of change of the transmission ratio when issuing a command to gradually return the transmission ratio to a value of 1 Memorize etc. It is made of ROM unit or the like. In this ROM section, a map (see FIG. 4) based on three elements regarding the change ratio of the transmission ratio, the steering angle, and the vehicle speed is recorded. Based on this three-dimensional map, the change rate of the transmission ratio at that time is determined.
[0011]
Next, the operating section 15 that operates in response to various commands (signals) from the control means 11 having such a configuration is operated by a signal from the transmission ratio return means 112 or the like, and this transmission ratio variable. A motor 151 that changes the transmission ratio of the means 1, a harmonic drive speed reduction mechanism that is driven by the motor 151, and includes a ring gear having a planetary gear mechanism or an internal gear, and an inner gear provided in the ring gear. And a speed reduction mechanism 155 formed by the following. The sun gear or one gear forming these reduction mechanisms 155 is connected to the steering shaft 21 on the steering handle 2 side to form the input side, and the ring gear or the other gear forms the power steering device 3. The output side of the speed reduction mechanism 155 is formed by being connected to the steering shaft 21 ′ on the steering gear mechanism 31 side.
[0012]
Further, a lock mechanism that is operated by a separately provided solenoid mechanism or the like is provided between the input side and the output side of the speed reduction mechanism 155 having such a configuration. The speed reduction function of the speed reduction mechanism 155 is fixed (locked) so that the steering shaft 21 on the steering handle 2 side and the steering shaft 21 'on the steering gear mechanism 31 side (see FIG. 1) are directly connected. It is. That is, a connecting means 152 for fixing the transmission ratio to a value of 1 with this lock mechanism is formed. The operation of the connecting means 152 is controlled based on a command (signal) from the connecting permission means 113 that forms a part of the control means 11 in FIG.
[0013]
As shown in FIG. 1, it is provided on the downstream side of the transmission ratio variable means 1 having such a configuration, and operates according to a command from the steering handle 2, that is, an operation (steering) of the steering handle 2. At the same time, the power steering device 3 that steers the steering wheel 9 to a predetermined position is operated according to the rotation angle (input) on the steering shaft 21 ′ side, and according to the operation of the steering gear mechanism 31. It is basically composed of a power assist mechanism 32 that operates and assists power for the operation (steering) of the steered wheels 9. In this embodiment, in the present embodiment, a hydraulic mechanism is employed as the power assist mechanism 32, and the pressure oil generated by the hydraulic pump 35 is power assisted via the control mechanism 33. The power cylinder and the power piston forming the mechanism 32 are supplied. The steering wheel 9 is appropriately steered by the action of the pressure oil supplied to the power assist mechanism 32. Further, the steering angle (cut angle) of the steered wheels 9 is fed back to the control means 11 via the steered wheel steering angle (cut angle) sensor 16.
[0014]
Next, the operation mode, particularly the motor overheat protection mode, of the present embodiment having such a configuration will be described with reference to the flowchart of FIG. That is, in the motor overheat protection mode for avoiding overheating of the motor 151 while the transmission ratio variable means 1 is operating, first, in step 1 (S1) of FIG. Is judged. At this time, when the motor is not in the overheat protection mode (in the case of N), in the next step (S2), the stage before the temperature of the motor 151 reaches a limit point described later, for example, the present embodiment In the embodiment, it is determined whether or not the motor temperature is a preventive temperature (X ° C.) that prevents the motor temperature from reaching the limit point. At this time, if the motor temperature is X ° C. or less, there is no problem even if the operation of the transmission ratio variable means 1, that is, the operation of the motor 151 is continued, the process proceeds to step 9 (S 9), The ratio variable state (VGRS control) is maintained.
[0015]
On the other hand, if it is determined in step 2 (S2) that the temperature of the motor 151 is equal to or higher than X ° C., if this state continues, the temperature of the motor 151 will eventually reach the limit point (in this embodiment, Y Therefore, it is necessary to stop the operation of the motor 151 by stopping the operation of the transmission ratio variable means 1. Therefore, it is necessary to prepare for this. Therefore, before that, first, the process proceeds to the next step 3 (S3), and the speed reduction mechanism 155 of the present system (transmission ratio variable means 1) is operated so that the transmission ratio becomes 1. The shift to the transmission ratio 1 is performed in accordance with what has been previously input to the ROM portion of the control means 11, for example, according to a map as shown in FIG. 4, taking into account the vehicle speed or steering angle at that time. Try to make it happen as quickly as possible. Specifically, this map takes the change ratio (transmission ratio change amount per unit time) when shifting to the transmission ratio 1 on the vertical axis, and the steering angle at the start of the transition on the horizontal axis. A plurality of maps corresponding to the vehicle speed are defined. As a result, when the steering angle is large, the change rate is decreased and the transmission ratio is gradually shifted to 1, and when the steering angle is small, the change ratio is increased and the transmission ratio is quickly shifted to 1. In addition, the transmission ratio is gradually shifted to 1 when traveling at a high speed, and the transmission ratio is quickly shifted to 1 when traveling at a low speed. In FIG. 4, two maps at high speed and low speed are shown, but the rate of change in vehicle speed during this time is determined by linear interpolation between these two maps, Alternatively, these maps are determined by a number of maps that are defined in small increments. Then, in the next step 4 (S4), it is determined whether or not the transmission ratio is a value of one. If it is determined in step 4 (S4) that the transmission ratio has a value of 1, the process proceeds to the next step 6 (S6), where the system is locked. At the same time, the power supply to the motor 151 is stopped and the motor overheat protection mode is entered. That is, the connection means 152 is operated by the determination of the connection permission means 113 in FIG. As a result, the input side and the output side of the speed reduction mechanism 155 are directly connected to each other, and the steering input from the steering handle 2 in FIG. 1 is directly transmitted to the power steering device 3. Will be steered.
[0016]
On the other hand, if it is determined in step 4 (S4) that the transmission ratio has not yet reached 1, whether or not the temperature of the motor 151 exceeds the limit Y.degree. C. in step 5 (S5). Determined. Here, if it is determined that the temperature exceeds the limit point Y ° C., the connecting means 152 (see FIG. 2) is immediately operated to avoid the occurrence of the inoperability of the motor 151. Put the system in a locked state. That is, the process is forcibly shifted to step 6 (S6). When it is determined that the temperature of the motor 151 does not reach the limit point Y ° C., the routine proceeds to step 9 (S9), where the normal transmission ratio variable control (VGRS control), and further the motor Move to the start of overheat protection mode.
[0017]
Next, in step 7 (S7), the temperature of the motor 151 drops (cools) during the system lock state in step 6 (S6), and the motor is not overheated (the temperature at this time is set to Z If it is determined from the signal from the motor temperature sensor 17 (see FIG. 2), the process proceeds to the next step 8 (S8) to unlock the system. Like that. That is, the connection is released. As a result, normal transmission ratio variable control (VGRS control) is performed. On the other hand, when it is determined that the temperature of the motor 151 is equal to or higher than the above Z ° C. and there is a possibility that the motor 151 is overheated again, the motor overheat protection mode is entered via the return step.
[0018]
As described above, in the present embodiment, the overheat protection of the motor is based on the limit point where the motor becomes inoperable, and the transmission ratio is set to 1 in advance in the previous prevention stage. Since the lock of the system, that is, the input side and the output side of the speed reduction mechanism 155 are directly connected based on the state of the ratio 1, when the steered wheel 9 goes straight in the locked state (connected state), The neutral position of the steering wheel 2 is not shifted, and the driver (driver) does not feel uncomfortable.
[0019]
【The invention's effect】
According to the present invention, a transmission ratio variable means that is provided in the middle of a steering transmission system that connects a steering handle and a steering wheel and that operates to change a transmission ratio by driving a motor, and the transmission ratio variable A transmission means comprising a coupling means that operates to fix the transmission ratio between the input side and the output side of the means according to the situation, and a control means that controls the operation of the transmission ratio variable means and the coupling means. With respect to the variable steering apparatus, a transmission ratio determining unit that operates when the control unit determines the connection operation of the connecting unit and determines whether the transmission ratio is a value of 1, and the transmission ratio A transmission ratio return means for driving the motor to drive the transmission ratio of the transmission ratio variable means to a value of 1 when the transmission ratio determined by the determination means is not a value of 1, and the transmission ratio of Value of 1 And the connection permitting means that operates so as to permit the operation of the connection means only when the connection handle is operated, so that the connection means is actuated to connect the steering wheel and the steering wheel. In this state, the neutral position of the steering wheel coincides with the neutral position of the steering wheel, and the neutral position of the steering wheel is not shifted (i.e., a phase shift occurs) when the steering wheel is in the straight traveling state. As a result, the driver (driver) does not feel uncomfortable.
[0020]
In addition, when the control means determines that there is a possibility that the operation of the motor may be abnormal, the structure is such that the connection means is forcibly connected. The system can be connected directly and the fail-safe function can be activated.
[Brief description of the drawings]
FIG. 1 is a skeleton diagram showing the overall configuration of the present invention.
FIG. 2 is a block diagram showing an overall configuration of a transmission ratio variable means constituting the main part of the present invention.
FIG. 3 is a flowchart showing an operation mode of the present invention.
FIG. 4 is a map showing the relationship between the amount of change in transmission ratio per unit time inputted in advance in a ROM section and the steering angle.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transmission ratio variable means 11 Control means 111 Transmission ratio discrimination means 112 Transmission ratio return means 113 Connection permission means 15 Actuator 151 Motor 152 Connection means 155 Deceleration mechanism 16 Steering wheel steering angle (steering wheel turning angle) sensor 17 Motor temperature sensor 18 Steering angle sensor 19 Vehicle speed sensor 2 Steering handle 21 Steering shaft 21 'Steering shaft 3 Power steering device 31 Steering gear mechanism 32 Power assist mechanism 33 Control mechanism 35 Hydraulic pump 9 Steering wheel

Claims (2)

A transmission ratio variable means that is provided in the middle of a steering transmission system that connects the steering handle and the steering wheel and that operates to change the transmission ratio by driving a motor, and an input side and an output of the transmission ratio variable means In a transmission ratio variable type steering apparatus comprising: a coupling means that operates so as to fix a transmission ratio between the two sides according to a situation; and a control means that controls the operation of the transmission ratio variable means and the coupling means. The control means is operated when the connection operation of the connection means is determined, and is determined by the transmission ratio determination means for determining whether or not the transmission ratio is a value of 1, and the transmission ratio determination means When the transmission ratio is not a value of 1, when the motor is driven and the transmission ratio return means operates so that the transmission ratio of the transmission ratio variable means becomes 1, the transmission ratio is a value of 1. Only above Transmission ratio to a connection permission unit operable to permit the operation of the imaging means, characterized in that it is so provided variable steering apparatus. 2. The variable transmission ratio steering apparatus according to claim 1, wherein the connecting means is forcibly connected when it is determined that the control means may cause an abnormality in the operation of the motor. A transmission ratio variable type steering device.

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