Vehicle control device

Abstract

To provide a control device of a vehicle capable of improving reliability and durability of a differential lock mechanism, by restraining the occurrence of an operation failure in a position detecting sensor being a differential lock position detecting means for detecting a differential lock state.SOLUTION: When the electronic control unit 80 starts or stops the hybrid vehicle 10, if a differential lock test execution condition (a predetermined period T1 or more has elapsed from the previous differential lock execution date Eday, or the completion of differential lock has not been detected in the previous differential lock) is satisfied in the differential lock operation history, differential lock is performed. When the differential is locked, the conduction of the differential lock mechanism 36 is confirmed, the position detection sensor 72 is also operated, and self-cleaning of the switch contact is performed by the movement of the switch contact. Therefore, occurrence of malfunction of the position detection sensor 72 is suppressed, and reliability and durability of the differential lock mechanism 36 are improved.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle equipped with a differential lock mechanism that limits differential movement of a differential gear device. [Background technology]

[0002] Vehicles that travel off-road, such as on muddy roads, or on snowy roads, are well known that are equipped with a so-called differential lock mechanism that limits the differential movement of a differential gear device. For example, the vehicle described in Patent Document 1 is such a vehicle. Patent Document 1 discloses that an actuator of a differential limiting mechanism (differential lock mechanism) provided in a differential gear device is controlled to perform differential locking. The differential locking is performed, for example, by the driver operating a differential lock switch. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-8460 Summary of the Invention [Problem to be solved by the invention]

[0004] The differential lock is activated by the driver operating the differential lock switch, but it may not be engaged for long periods of time unless the vehicle is driving on an off-road vehicle such as a muddy road or a snowy road. If the differential lock is not engaged for a long period of time, the position detection sensor that detects the differential lock state provided in the differential lock mechanism will also not operate for a long period of time, which could cause the contacts of the detection switch in the sensor to oxidize or dirt and debris (sludge) contained in the differential oil to accumulate on the contacts, resulting in poor conductivity of the detection switch, i.e., malfunction of the position detection sensor.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle control device that can prevent malfunctions of the position detection sensor, which is a differential lock position detection means that detects the differential lock state, and can improve the reliability and durability of the differential lock mechanism. [Means for solving the problem]

[0006] The gist of the present invention is (a) a control device for a vehicle equipped with a differential lock mechanism that limits the differential of a differential gear device and that engages the differential by operating a differential lock switch, and (b) when the vehicle starts or stops, the differential lock is engaged if a predetermined condition is met in the operation history of the differential lock. [Effects of the Invention]

[0007] According to the present invention, the control device locks the differential when the vehicle is started or stopped if a predetermined condition is met in the differential lock operation history. As a result, when the vehicle is started or stopped, if a predetermined condition is met in the differential lock operation history, the differential is locked. This checks the continuity of the differential lock mechanism and also activates the position detection sensor, which is a differential lock position detection means, and the switch contacts move to perform self-cleaning. This prevents malfunctions in the position detection sensor and improves the reliability and durability of the differential lock mechanism.

[0008] Preferably, the differential lock mechanism has a position detection sensor as differential lock position detection means, and the position detection sensor is a contact switch. By doing so, when the differential is locked, the switch contact moves to perform self-cleaning, thereby preventing malfunction of the position detection sensor.

[0009] Preferably, the contact switch is a slide-type contact switch, whereby when the differential lock is engaged, the switch contact moves to perform self-cleaning, thereby preventing malfunction of the position detection sensor.

[0010] Preferably, the differential lock is activated when a predetermined period of time has elapsed since the previous differential lock activation, as a predetermined condition of the differential lock activation history, thereby preventing the position detection sensor from being inactive for a long period of time and suppressing malfunctions of the position detection sensor.

[0011] Preferably, the previous differential lock operation includes the differential lock operation of the present invention and the differential lock operation by the driver operating the differential lock switch. This reduces the number of times the differential lock operation of the present invention is performed, avoiding unnecessary self-cleaning of the position detection sensor and reducing power consumption.

[0012] Preferably, the operation of the differential lock is terminated when the differential lock is detected by the position detection sensor, thereby ensuring that the operation of the differential lock is terminated.

[0013] Preferably, the differential lock operation is terminated after a predetermined period of time has elapsed even if the position detection sensor does not detect the differential lock, thereby preventing the differential lock operation from continuing without being terminated.

[0014] Preferably, the operation of the differential lock is terminated when the start of preparation for travel is detected, so that even if the differential lock is in operation, when the start of preparation for travel is detected, the vehicle can be immediately switched to a travel-enabled state.

[0015] Preferably, the start of preparation for travel is detected by, for example, a shift operation by the driver.

[0016] Preferably, even if the position detection sensor does not detect the differential lock during the operation of the differential lock, an abnormality determination of the differential lock mechanism is not made, thereby avoiding determining that an abnormality has occurred when meshing has not been achieved due to the position of a movable part in the differential gear device. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram illustrating a main part of a vehicle to which the present invention is applied, and also a diagram illustrating a main part of a control system provided in the vehicle. [Figure 2] 2 is a diagram illustrating an example of a schematic configuration of a differential gear device mounted on the vehicle of FIG. 1. FIG. [Figure 3] 3 is a flowchart illustrating a main part of the control operation of the electronic control device. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0019] 1 is a diagram illustrating the main parts of a vehicle 10 to which the present invention is applied, and also illustrates the main parts of a control system provided in the vehicle 10. The vehicle 10 is a front-wheel drive vehicle, a rear-wheel drive vehicle, or a four-wheel drive vehicle.

[0020] In FIG. 1, a vehicle 10 includes a prime mover 12, such as an engine or an electric motor, a transmission 14 that changes the rotation speed of the prime mover 12, a pair of left and right drive wheels 16, 18, and a differential gear device 30 connected to the pair of left and right drive wheels 16, 18 via a pair of left and right drive shafts 20.

[0021] The differential gear device 30 transmits the drive torque transmitted from the transmission 14 via the propeller shaft 24 evenly to the drive wheels 16, 18 connected to each other via the drive shafts 20 while allowing differential rotation between them. The differential gear device 30 also includes a differential lock mechanism 36 that limits differential rotation and transmits torque to the drive wheels 16, 18 at the same rotation. A differential lock control signal Sdk is output to the differential lock mechanism 36 from an electronic control device 80 (described later) to lock or unlock the differential.

[0022] The vehicle 10 also includes a differential lock switch 90. The differential lock switch 90 is a switch operated by the driver to set the differential lock. The differential lock switch 90 is, for example, a lock-type switch that switches between on and off, and a differential lock operation signal Kdk indicating whether to lock or release the differential lock is supplied to the electronic control unit 80 depending on whether the switch is on or off.

[0023] FIG. 2 is a diagram illustrating an example of a schematic configuration of a differential gear device 30 mounted on the vehicle 10. As shown in FIG.

[0024] In FIG. 2, the differential gear device 30 includes a housing 32, a differential unit 34, a differential lock mechanism 36, a plurality of bearings 38, and the like.

[0025] The housing 32 is a non-rotating member fixed to the vehicle body. The differential unit 34 is connected to the propeller shaft 24. The drive shaft 20 is connected to the differential unit 34.

[0026] The differential unit 34 is housed in the housing 32. The differential unit 34 includes a differential ring gear 40, a differential case 42, a pair of differential side gears 44, a pair of differential pinions 46, a pinion shaft 48, and the like.

[0027] The differential ring gear 40 is integrally connected to the outside of the differential case 42 and meshes with the propeller shaft 24. The differential case 42 is rotatably supported by the housing 32 via bearings 38. The differential side gear 44, differential pinion 46, and pinion shaft 48 are housed within the differential case 42. The differential case 42 is formed with a bore portion 42a, which is a through hole into which the drive shaft 20 is fitted so as to be rotatable relative to the differential case 42. The differential side gear 44 has spline teeth formed on an inner peripheral surface 44a of the through hole into which the drive shaft 20 is fitted so as not to be rotatable relative to the differential case 42. The differential unit 34 configured in this manner is a known differential mechanism that distributes the power of the power source transmitted from the propeller shaft 24 to the left and right drive wheels.

[0028] The differential lock mechanism 36 includes a clutch 50, an actuator 60, a rotating plate 70, a position detection sensor 72, a drive device 74 (not shown), and the like.

[0029] The clutch 50 is a dog clutch (i.e., a meshing clutch) that selectively connects or disconnects, i.e., disconnects, the differential case 42 and the differential side gear 44 on the clutch 50 side. The clutch 50 is moved by an actuator 60 between an engaged position and a disengaged position, i.e., switched between an engaged state and a released state.

[0030] The actuator 60 is fixedly mounted within the housing 32 and includes a plunger 62, a solenoid 64, a return spring 66, and the like. When the electronic control device 80 outputs a differential lock control signal Sdk to the drive device 74, instructing the drive device 74 to lock the differential, the solenoid 64 is driven by current from the drive device 74, causing the plunger 62 to generate a predetermined amount of thrust. The actuator 60 is a device that uses this thrust to move the clutch 50 to the engaged position. When the electronic control device 80 outputs a differential lock control signal Sdk to the drive device 74, instructing the drive device 74 to release the differential lock, the drive of the solenoid 64 by the drive device 74 is stopped, and the clutch 50 is returned to the disengaged position by the biasing force of the return spring 66. The return spring 66 is a spring that constantly biases the clutch 50 to return to the disengaged position. The drive device 74 also includes a differential lock current sensor 76. The differential lock current sensor 76 is a sensor that detects the drive current of the solenoid 64 , and the detected drive current value Idk is supplied to the electronic control unit 80 .

[0031] When the clutch 50 is in a disengaged state, power input to the differential case 42 is transmitted to the left and right differential side gears 44 via the pinion shaft 48 and the differential pinion 46 in this order. When the clutch 50 is in a disengaged state, the differential unit 34 is in a differential state in which a rotational difference between the left and right differential side gears 44 is permitted. On the other hand, when the clutch 50 is in an engaged state, the differential case 42 and the differential side gears 44 on the clutch 50 side are integrally connected, so that the power input to the differential case 42 is also directly transmitted to the differential side gears 44 on the clutch 50 side. When the clutch 50 is in an engaged state, the differential unit 34 is in a differential-locked state in which the differential state is restricted by the differential case 42 and the left and right differential side gears 44 being rotated integrally. In other words, the differential gear device 30 is in a differential-locked state.

[0032] The rotating plate 70 is a rotating member connected to the differential case 42 on the clutch 50 side. In conjunction with the movement of the clutch 50 between the engaged position and the disengaged position (left and right on the paper surface of FIG. 2), the rotating plate 70 also moves left and right on the paper surface.

[0033] The position detection sensor 72 is a sensor equipped with a sliding contact switch that serves as differential lock position detection means for detecting whether the clutch 50 is in the engaged position, i.e., whether the differential is locked. The contacts of the detection switch within the position detection sensor 72 move in accordance with the movement of the rotating plate 70, and a signal (hereinafter referred to as the differential lock position signal) Pdk of a level corresponding to the movement position of the rotating plate 70 is output from the position detection sensor 72. By electrically detecting the differential lock position signal Pdk when the clutch 50 is in the engaged position, it is possible to detect that the clutch 50 has moved to the engaged position, i.e., that the differential lock has been completed. The differential lock position signal Pdk is supplied to the electronic control unit 80.

[0034] The vehicle 10 is equipped with an electronic control unit 80 that includes a control device for the vehicle 10. The electronic control unit 80 is configured to include a so-called microcomputer.

[0035] The electronic control unit 80 switches between a differential lock state and a differential unlock state of the differential gear unit 30 by operating a differential lock switch 90. When the driver turns on the differential lock switch 90 (the differential lock operation signal Kdk is turned on), the electronic control unit 80 outputs a differential lock control signal Sdk to the drive unit 74 to instruct the differential to be locked, thereby locking the differential. When the differential lock switch 90 is turned off (the differential lock operation signal Kdk is turned off), the electronic control unit 80 outputs a differential lock control signal Sdk to the drive unit 74 to instruct the differential to be unlocked, thereby unlocking the differential.

[0036] As mentioned above, the differential lock is activated by the driver operating the differential lock switch 90, but it may not be activated for an extended period of time unless the vehicle is driving on an off-road (e.g., muddy) road or on a snowy road. If the differential lock is not activated for an extended period of time, the position detection sensor 72 for detecting the locked state of the differential lock mechanism 36 will also not operate for an extended period of time. This can cause oxidation of the detection switch contacts within the sensor, or accumulation of dirt and debris (sludge) contained in the differential oil, etc., on the contacts, which can lead to poor continuity of the detection switch, i.e., malfunction of the position detection sensor 72.

[0037] Therefore, the electronic control device 80 of this embodiment performs the differential lock test described below when the vehicle 10 starts or stops, thereby confirming the continuity of the differential lock mechanism 36 and performing self-cleaning of the switch contacts by operating the position detection sensor 72.

[0038] FIG. 3 is a flowchart illustrating the control operation of the differential lock test performed by the electronic control unit 80, which is executed, for example, when the vehicle 10 is started or stopped.

[0039] First, in step S10 (hereinafter, "step" will be omitted), it is determined whether or not the differential lock test execution condition is met. The differential lock test execution condition is determined to be met when at least one of the following conditions is met: (A) a predetermined period T1 or more (e.g., three months or more) has elapsed since the last differential lock execution date Eday, and (B) differential lock completion has not been detected in the previous differential locks (the incompletion count Cnt, which is counted up when differential lock completion is not detected, is a value greater than 0). The predetermined period T1 is set in advance by design or experiment. If the determination in S10 is negative, this routine is terminated. The differential lock test execution condition corresponds to the "predetermined condition" in this invention.

[0040] If the determination in S10 is affirmative, the process proceeds to S20, where the electronic control device 80 outputs a differential lock control signal Sdk to the drive device 74 to instruct the differential to be locked, thereby driving the solenoid 64 with current and starting the operation of the differential lock.

[0041] Next, in S30, the continuity of the differential lock mechanism 36 is confirmed by determining whether the current drive of the solenoid 64 is normal. This determination is made, for example, by determining whether the drive current value Idk is within a predetermined current range (Ia≦Idk≦Ib). The lower limit Ia and upper limit Ib used in the determination are set in advance by design or experiment. If the determination in S30 is negative, a differential lock abnormality is determined in S40, and then in S110, the output of the differential lock control signal Sdk to the drive device 74 is stopped, the current drive of the solenoid 64 is also stopped, the differential lock operation is terminated, and this routine is ended. The differential lock abnormality determination may result in, for example, the operation of the differential lock mechanism 36 being stopped, or a warning or alert notifying the differential lock abnormality is displayed on the console.

[0042] If the determination in S30 is positive, then in S50 it is determined whether the start of preparation for travel has been detected. This determination is made, for example, by determining whether the driver has performed a shift operation. If the determination in S50 is positive, then the routine transitions to S110, where the differential lock operation is terminated, and this routine is ended. As a result, even if the differential lock test is in operation, if the start of preparation for travel is detected, the vehicle is immediately switched to a ready-to-travel state. If the determination in S50 is negative, then in S60 it is determined whether completion of differential lock has been detected. This determination is made, for example, by determining whether movement of the clutch 50 to the engaged position is detected by the differential lock position signal Pdk from the position detection sensor 72. If the determination in S60 is negative, then in S70 it is determined whether a predetermined period T2 has elapsed since the start of differential lock in S20. If the determination in S70 is negative, then the determination in S50 is repeated. If the determination in S70 is affirmative, in S80, the incompletion count Cnt is counted up (Cnt=Cnt+1), the process proceeds to S110, the differential lock operation is terminated, and this routine is terminated. A positive determination in S70 is made, for example, when movement of the clutch 50 to the meshed position is not detected within a predetermined period of time T2. However, because the clutch 50 may not move to the meshed position depending on the position of moving parts within the differential gear device 30, no abnormality determination is made even if the determination in S70 is affirmative. The predetermined period of time T2 is set in advance by design or experiment.

[0043] If the judgment in S60 is positive, in S90, the incomplete count Cnt is cleared (Cnt = 0), and then in S100, the differential lock implementation date Eday is updated to the current date, and the process transitions to S110, where the differential lock operation is terminated and this routine is ended.

[0044] Preferably, the incomplete count Cnt and the differential lock implementation date Eday in the above-described flowchart may be updated not only by the differential lock test but also by the driver operating the differential lock switch 90. This reduces the number of times the differential is locked due to the differential lock test, and prevents unnecessary self-cleaning of the switch contacts. It also reduces power consumption.

[0045] As described above, according to this embodiment, when the vehicle 10 starts or stops, the electronic control device 80 locks the differential if the differential lock test execution condition is met in the differential lock operation history (either the predetermined period T1 or more has elapsed since the last differential lock execution date, Eday, or the completion of differential locking has not been detected in the previous differential locks). As a result, if the differential lock test execution condition is met in the differential lock operation history when the vehicle 10 starts or stops, the differential is locked, which checks the continuity of the differential lock mechanism 36 and also activates the position detection sensor 72, which moves the switch contacts to perform self-cleaning. This prevents malfunctions of the position detection sensor 72 and improves the reliability and durability of the differential lock mechanism 36.

[0046] Furthermore, according to this embodiment, the differential lock mechanism 36 has a position detection sensor 72, which is a differential lock position detection means, and a contact switch is used as the position detection sensor 72. As a result, when the differential is locked, the switch contacts move to perform self-cleaning, preventing malfunction of the position detection sensor 72.

[0047] Furthermore, according to this embodiment, a slide-type contact switch is used as the contact switch of the position detection sensor 72. As a result, when the differential is locked, the switch contact moves to perform self-cleaning, thereby preventing malfunction of the position detection sensor 72.

[0048] Furthermore, according to this embodiment, the differential lock test is performed when a predetermined period of time T1 or more has elapsed since the last differential lock execution date, Eday, as a condition for performing the differential lock test. This prevents the position detection sensor 72 from being inoperative for a long period of time, and suppresses malfunctions of the position detection sensor 72.

[0049] Furthermore, according to this embodiment, the last differential lock implementation date Eday is updated not only by the differential lock test but also by the differential lock implemented by the driver operating the differential lock switch 90. This reduces the number of times the differential lock operation of the present invention is implemented, and prevents unnecessary self-cleaning of the position detection sensor 72. It also reduces power consumption.

[0050] Furthermore, according to this embodiment, the differential lock test operation is terminated when the completion of differential locking is detected by the position detection sensor 72. This ensures that the differential locking operation is terminated reliably.

[0051] Furthermore, according to this embodiment, the differential lock test operation is terminated after the predetermined period T2 has elapsed even if the position detection sensor 72 does not detect that the differential lock has been completed. This prevents the differential lock operation from continuing without being terminated.

[0052] Furthermore, according to this embodiment, the differential lock test is terminated when the start of preparation for travel is detected. As a result, even if the differential lock test is in progress, when the start of preparation for travel is detected, the vehicle is immediately switched to a ready-to-travel state.

[0053] Furthermore, according to this embodiment, the start of preparation for traveling is detected by, for example, a shift operation by the driver.

[0054] Furthermore, according to this embodiment, even if the position detection sensor 72 does not detect completion of differential lock during the differential lock test, an abnormality determination is not made for the differential lock mechanism 36. This avoids determining that there is an abnormality when meshing is not achieved due to the position of the moving parts in the differential gear unit 30.

[0055] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0056] For example, in the above-described embodiment, the present invention is applied to a vehicle 10 equipped with a differential lock mechanism 36 that limits the differential between the pair of left and right drive wheels 16, 18, but is not limited to this. For example, the present invention can also be applied to a four-wheel drive vehicle equipped with a center differential lock mechanism that limits the differential between the front and rear wheels.

[0057] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0058] 10: Vehicle 30: Differential gear device 36: Differential lock mechanism 80: Electronic control device (control device) 90: Differential lock switch

Claims

[Claim 1] A control device for a vehicle that is equipped with a differential lock mechanism that limits differential operation of a differential gear device and that performs differential lock by operating a differential lock switch, When the vehicle is started or stopped, if a predetermined condition is satisfied in the operation history of the differential lock, the differential lock is performed. A vehicle control device characterized by:

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