Safe parking system

Abstract

A safety parking system has: an electric motor that generates torque for driving a vehicle; a terminal drive that has side gears that are drivingly connected to the electric motor to output the torque to drive wheels, a differential gear that locks differential between the side gears, and an actuator that releases the lock of the differential; an ignition key that has an on position and an off position; a differential lock switch that has an open position and a closed position; a switch that switches operation and stop of the actuator; and a controller that is electrically connected to the ignition key, the differential lock switch, and the switch and controls the actuator, the controller being configured to, when detecting that the ignition key is in the off position, stop the actuator if the differential lock switch is in the open position, and not operate the actuator if the differential lock switch is in the closed position, thereby locking the differential of the differential gear in any case to park the vehicle.

Description

Technical Field

[0001] The following disclosure relates to a system for safely parking a vehicle, and more specifically, to a safe parking system that uses differential locking of differential gears to ensure that the vehicle stops. Background Technology

[0002] In most cases, vehicles have a parking brake system independent of the foot brake for sustained stopping, i.e., parking. A classic example of a parking brake is a mechanism that uses cables to operate drum brakes mounted on the left and right rear wheels. In this example, the wheels are directly braked and there is no need for backup using a battery, thus providing excellent safety. Another example is a pawl clutch or pawl located within the transmission to stop the rotation of the gears. In this example, there is a potential problem because the wheels are not directly braked. That is, the left and right wheels are usually connected via differential gears to allow for speed differences. Therefore, even when parked, the left and right wheels can rotate in opposite directions. Thus, if the vehicle cannot remain stationary due to its posture, it may roll. An auxiliary means of locking the wheels is needed.

[0003] Patent documents 1 and 2 disclose the relevant technologies.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Patent Application Publication 2018 / 008160A1

[0007] Patent Document 2: Japanese Patent Application Publication No. 2018-200093 Summary of the Invention

[0008] Conventional parking brakes inevitably increase weight for safe parking, making them unsuitable for particularly lightweight vehicles such as mini-cars and buggies. The system disclosed below addresses the problem of achieving safe parking without relying on wheel locking mechanisms.

[0009] According to one aspect, a safe parking system includes: an electric motor that generates torque for driving a vehicle; a terminal driver that includes: a differential gear having side gears connected to the electric motor and outputting the torque to drive wheels respectively, and the differential between the side gears being locked; and an actuator for releasing the differential lock; an ignition key having an on position and an off position; a differential lock switch having an open position and a closed position; a switcher that switches the operation and stop of the actuator; and a controller electrically connected to the ignition key, the differential lock switch and the switcher and controlling the actuator, the controller being configured to, when detecting that the ignition key is in the off position, stop the actuator if the differential lock switch is in the open position, and not operate the actuator if the differential lock switch is in the closed position, thereby locking the differential of the differential gear in any situation to stop the vehicle. Attached Figure Description

[0010] Figure 1 This is a block diagram of the system.

[0011] Figure 2 This is a final-drive elevation section view based on an example.

[0012] Figure 3 It is a flowchart of the algorithm that constitutes the system.

[0013] Figure 4 It is part of the flowchart, and it is the part related to the processes in operation. Detailed Implementation

[0014] Several exemplary embodiments will be described below with reference to the accompanying drawings. In the following description, sometimes right and left are distinguished, and sometimes front and back are distinguished, but these are only for the purpose of illustration. Of course, embodiments in which left and right and front and back are reversed are also possible.

[0015] The system of this embodiment is applicable to relatively lightweight vehicles such as three-wheeled scooters, golf carts, microcars, or small cars, and is particularly suitable for battery-powered electric vehicles. Of course, it can also be applied to general vehicles, and also to vehicles with six or more wheels. In the following description, an example based on a rear-wheel drive four-wheeled vehicle with an electric motor directly integrated into the final drive is used, but this is merely for illustrative purposes.

[0016] Reference Figure 1The vehicle has front wheels 1F and rear wheels 1R as drive wheels. The front wheels 1F are coupled to a steering wheel 9, and their direction can be changed by steering the steering wheel 9, thereby changing the direction of travel of the vehicle. The rear wheels 1R are driven by an electric motor 3 via a terminal driver 5, receiving its torque to make the vehicle move forward or backward. The terminal driver 5, as described later, contains a differential gear to differentially distribute torque to the left and right rear wheels 1R.

[0017] Reference Figure 2 The terminal drive 5 generally comprises: a housing 31 that receives torque from the electric motor 3; a differential gear having a pair of side gears 33; a clutch 35 that locks the differential between the side gears 33 by engagement; and a force application unit 37 that applies force to the clutch 35 to engage the clutch 35. The housing 31 is driven to engage with the electric motor 3 via a conveyor belt, sprocket, or gear engagement, and rotates about axis C by receiving torque. The housing 31 and the pair of side gears 33 are driven to engage via a differential gear set, and the received torque is output from the two side gears 33 to the two drive wheels 1R respectively.

[0018] In this embodiment, the clutch 35 locks the differential between the side gears 33 by fixing one side gear 33 to the housing 31, but the locking of the differential can be achieved based on other suitable constructions. As is readily understood, the device has a construction similar to a locking differential, but the clutch 35 is always engaged by the force application unit 37, and the differential between the left and right side gears 33 is locked in a stable state. The clutch 35 is disengaged only when the actuator 39 is powered on and operates, the lock is released, the differential gears function and allow the differential between the left and right side gears 33. That is, a normally closed (locked in a stable state) locking differential. Of course, when the terminal drive 5 loses power, the clutch 35 is engaged by the force application unit 37, thereby maintaining the differential locked state.

[0019] Based on the force-applying unit 37, other force-applying units 41 that apply force to the clutch components in the opposite direction are not necessary, but a terminal drive 5 may also be included. This helps to reduce the burden on the actuator 39, thereby helping to reduce energy consumption.

[0020] Alternatively, in the system, instead of the normally closed locking differential, a differential that maintains a locked state by means of a latching mechanism or the like can be used, or a shifting device that can be disengaged only for a limited time can be used.

[0021] return Figure 1For reference, a vehicle may have a brake 7 for braking, which could be a brake built into the electric motor 3 and connected to its rotor shaft. Alternatively, the vehicle may have drum or disc brakes mounted on each wheel. Furthermore, the brake 7 could be an electromagnetic brake, which can be used not only for vehicle braking but also for power regeneration. Of course, this is not only necessary when power is available, but even when power is unavailable, the electric motor 3 and the electromagnetic brake can apply a load to the rotor shaft to brake the vehicle. In addition to the electromagnetic brake, the brake 7 may also include a mechanical brake that operates via a spring structure or the like when power is lost, which can brake or lock the rotor shaft.

[0022] In addition to the aforementioned structure, the system of this embodiment generally includes a controller 11, an accelerator pedal 13, a brake pedal 15, an ignition key 17, a differential lock switch 19, a battery 21, and a switch 29. The accelerator pedal 13, brake pedal 15, ignition key 17, and differential lock switch 19 are all input devices electrically connected to the controller 11. The driver uses these devices to issue commands to the controller 11, performing vehicle operations such as starting, accelerating, braking, stopping, and parking. The battery 21 not only supplies power to the electric motor 3, thus becoming the vehicle's power source, but also, via the switch 29, is electrically connected to the actuator 39 in the terminal driver 5, causing it to operate, thereby supplying power to the controller 11 and causing it to operate as well.

[0023] The ignition key 17 is a rotary switch, for example, used to switch the system on and off, and has at least an on position and an off position. This can be a switch that is turned when a key is inserted, or it can be a dial without a keyhole. The ignition key 17 can also function as a gear shifter, gear lever, or selector. In this case, the on position includes at least a neutral position (N) and a drive position, and the drive position can further include a forward position (F) and a reverse position (R). Furthermore, the forward position (F) can be further divided into multiple stages, or may further include other positions. Of course, the gear shifter, gear lever, or selector can also be independent of the ignition key 17.

[0024] The differential lock switch 19 is a switch such as a toggle switch, push button, or slide switch used for operating the clutch 35, and has at least an open position OP and a closed position CL. Details will be described later. When the differential lock switch 19 is in the open position OP, differential operation in the terminal drive 5 is allowed; when in the closed position CL, the differential operation is locked. The differential lock switch 19 can be independent of the ignition key 17 and other switches, as shown in the diagram, or it can be integrated with them.

[0025] The system may also include an indicator showing whether the differential is locked. The indicator may be an illumination built into the differential lock switch 19, or it may be a display device independent of the lock switch 19. Alternatively, or in addition to an indicator, a display device utilizing a liquid crystal, organic light-emitting diode, or laser projection may be used, and the locking / unlocking of the differential may be indicated by symbols or icons displayed on the display device. Furthermore, or in addition to these, a warning sound emitted from an audio device such as a speaker may be used as an alternative.

[0026] Battery 21 is the vehicle's primary power source, supplying or deactivating power to various parts of the vehicle based on the on / off state of the ignition key 17. Battery 21 can be a secondary battery such as a lithium-ion battery, but it can also be a primary battery, or a battery with self-generating capabilities such as a fuel cell. In the case of a secondary battery, it can typically be charged by an external power source, or the vehicle itself may have a generator that charges while driving, a so-called hybrid vehicle structure.

[0027] To charge battery 21, the system may include a battery charger 23, and the controller 11 may also have the function of controlling it. The battery charger 23 can also connect to an external charger PS to receive power from it and charge battery 21. Alternatively, the battery charger 23 can replace the external charger PS, or receive power from the vehicle's alternator in addition to the external charger PS.

[0028] To achieve high output, battery 21 has a relatively high rated voltage, such as 48V, but the system can also include a secondary battery 25 with a lower rated voltage. The secondary battery 25, for example, has a rated voltage of 12V and can be specifically used to drive electrical components requiring less power. For example, controller 11 typically operates powered by the secondary battery 25.

[0029] The auxiliary battery 25 is charged by receiving power from the battery 21, but the controller 11 can also have its control function in order to utilize the DC-DC converter 27 to step down the voltage from 48V to 12V.

[0030] Switch 29 is electrically connected to controller 11, which intermittently controls the power supply to actuator 39. Switch 29 can utilize a relay, which can be an electromagnetic relay, reed relay, solid-state relay, or equivalent relay. Alternatively, it can use power semiconductors such as thyristors, insulated-gate bipolar transistors, or MOSFETs to control the power supply instead of a relay.

[0031] Switch 29 is located between battery 21 or auxiliary battery 25 and actuator 39, controlling the power supply to actuator 39. For example... Figure 1 As shown by the solid line, the switch 29 can be located outside the controller 11, or it can be built into the controller 11 as shown by the dashed line. In the case of being built into the controller 11, the controller 11 directly supplies or disconnects power to the actuator 39, either physically or at least outwardly.

[0032] When switch 29 is open (disconnected), actuator 39 is not powered, so clutch 35 is closed (engaged), and the differential in terminal drive 5 is locked. When switch 29 is closed (engaged), actuator 39 is activated, clutch 35 is disengaged, and differential is allowed.

[0033] The controller 11 can utilize a computer chip configured to perform the series of processes described later, in cooperation with software. Examples of computer chips include electronic control units (ECUs) or equivalent computer chips used in vehicles to control their various components. Multiple ECUs can also be interconnected via a controller area network (CAN) communication bus. Alternatively, some or all of the series of processes described later can be executed without relying on software, through combinations of logic circuits such as AND, OR, and NOT. That is, some or all of the controller 11 can also be circuits configured to control the supply and disconnection of power to the motor 3, brake 7, and actuator 39 based on the operation of key 17 and switch 19. This circuit can be a fixed circuit or a programmable circuit.

[0034] Controller 11, for example, according to Figure 3 The algorithm shown performs actions to assist the driver in starting, accelerating, braking, stopping, and parking the vehicle. This algorithm can be executed by a single controller 11 or in collaboration with other ECUs. Furthermore, to perform these controls, controller 11 can also be electrically connected directly or via other ECUs to various sensors, such as vehicle speed sensors, axle speed sensors, or clutch position sensors.

[0035] Reference Figure 3 When starting the vehicle, the driver first operates the ignition key 17 and turns it on. When the ignition key 17 is turned on, the controller 11 is activated and performs predetermined settings. If it is not turned on, no action is taken; the driver may need to operate the ignition key 17 again, or the vehicle should be inspected.

[0036] The controller 11 then performs self-diagnosis. As a result, if an abnormality is detected, it can store fault information and stop itself. The fault information can also be communicated to the driver via indicators, visual displays, or audio devices. In this case, the driver should also inspect the vehicle.

[0037] When the controller 11 is properly started via these devices, the driver is able to begin driving the vehicle. Based on the operation of the accelerator pedal 13, brake pedal 15, ignition key 17, and differential lock switch 19, the controller 11 controls the electric motor 3, brake 7, and switch 29 (and therefore clutch 35) to move, brake, or stop the vehicle appropriately.

[0038] During continuous driving, the controller 11 constantly or periodically monitors whether the ignition key 17 is turned off. If it is not turned off, it can be inferred that the driver intends to continue driving.

[0039] Reference Figure 4 The procedure for handling the situation where the ignition key 17 is not disengaged is explained. The controller 11 further determines whether the ignition key 17 (or the gear shifter, gear shift lever, or selector) is in the neutral position N.

[0040] When the vehicle is in neutral (N), it is assumed that the driver intends to temporarily stop, so the controller 11 engages the brake 7 to bring the vehicle to a stop. Next, the controller 11 determines whether the differential lock switch 19 is in the open position (OP). If the controller 11 determines that the vehicle is in the open position (OP) based on the indication from the differential lock switch 19, it activates the actuator 39 (connects the switch 29) to allow differential operation. If the controller 11 determines that the vehicle is not in the open position (OP) (i.e., in the closed position (CL)), it deactivates the actuator 39 (disconnects the switch 29) to lock the differential operation.

[0041] When not in neutral position N (i.e., forward or reverse position), it is presumed that the driver intends to move the vehicle forward, so the controller 11 activates the motor 3. At this time, according to the indication of the differential lock switch 19, the controller 11 activates the actuator 39 (connects the switch 29) to allow differential operation when it is determined to be in the open position OP, and deactivates the actuator 39 (disconnects the switch 29) to lock the differential operation when it is determined to be not in the open position OP (i.e., in the closed position CL).

[0042] In either case, the controller 11 can notify the driver of the differential locking / unlocking, which, as described above, can be done via an indicator, image display device, or audio device. Control returns to... Figure 3 b) The driver can continue driving the vehicle. The driver can judge the road conditions and choose whether to engage differential lock by operating the differential lock switch 19 to move the vehicle.

[0043] Refer again Figure 3 When the driver wants to stop the vehicle, he first presses the brake pedal 15 to activate the brake 7 and bring the vehicle to a stop. At this time, the controller 11 can also use, for example, a vehicle speed sensor to confirm that the vehicle has stopped.

[0044] As described above, the controller 11 continuously or periodically monitors whether the ignition key 17 is not disconnected. When the controller 11 detects that the ignition key 17 is disconnected, it then determines whether the differential lock switch 19 is in the open position OP. If it determines that the differential lock switch 19 is in the open position OP, the controller 11 disconnects the actuator 39 (disconnects the switch 29) contrary to the indication of the differential lock switch 19. Alternatively, the controller 11 may also force the differential lock switch 19 to the closed position CL. Alternatively, the controller 11 may also directly control the battery 21 (or auxiliary battery 25) to cut off the power supply to the actuator 39. In either case, the clutch 35 is closed (engaged), and the differential is locked.

[0045] On the other hand, when it is determined that the clutch 35 is not in the open position OP (i.e., in the closed position CL), the clutch 35 should already be closed (engaged), so the controller 11 does not operate the actuator 39 (switcher 29). Of course, the controller 11 can also explicitly set the actuator 39 to disconnect (disconnect the switch 29), or it can also cut off the power supply from the battery 21 (or the auxiliary battery 25).

[0046] In either case, the differential in the terminal driver 5 is locked, preventing the vehicle from rolling and thus allowing for safe parking. Then, the controller 11 shuts itself down.

[0047] According to the system, when the vehicle needs to be stopped, the differential locking clutch 35 is always closed, so the vehicle does not roll, and the vehicle can be safely stopped simply by braking the rotor shaft. That is, a mechanism like a parking brake that locks the drive wheels is not needed for stopping. Furthermore, since a normally closed differential is used, locking the differential does not require electricity, and the battery is not consumed when the vehicle is stopped. This embodiment has advantages in terms of weight reduction and power consumption reduction, and it would be particularly beneficial if applied to relatively lightweight, battery-powered vehicles. Of course, any device that locks the differential when there is no power supply can be used instead of a normally closed differential.

[0048] Several implementation methods have been described, but modifications or variations can be made to the implementation methods based on the disclosure.

Claims

1. A safe parking system, characterized by, Possessing: an electric motor that generates torque for driving a vehicle; a final drive that possesses a side gear that is drivingly connected with the electric motor to output the torque to drive wheels respectively and a differential gear whose differential between the side gears is locked; an ignition key that has an on position and an off position; a differential lock switch that has an open position and a closed position; a switch that switches operation and stop of the actuator; and a controller that is electrically connected with the ignition key, the differential lock switch, and the switch and controls the actuator, the controller being configured to, when it is detected that the ignition key is in the off position, stop the actuator if the differential lock switch is in the open position and not operate the actuator if the differential lock switch is in the closed position, thereby locking the differential of the differential gear in either case to stop the vehicle, the safety parking system further possessing: a shifter that has at least a drive position and a neutral position; and a brake that brakes the electric motor, the controller being configured to be electrically connected with the shifter and the brake and operate the brake when the ignition key is in the on position and the shifter is in the neutral position.

2. The safety parking system according to claim 1, wherein the controller is configured to, after operating the brake, operate the actuator if the differential lock switch is in the open position and stop the actuator if the differential lock switch is in the closed position.

3. The safety parking system according to claim 1, wherein the controller is configured to be electrically connected with the electric motor and operate the electric motor only when the ignition key is in the on position and the shifter is in the drive position.

4. The safety parking system according to claim 3, wherein the controller is configured to, after operating the electric motor, operate the actuator if the differential lock switch is in the open position and stop the actuator if the differential lock switch is in the closed position.

Images