Drive unit and electric vehicle

Abstract

The present invention addresses the problem of providing a drive unit and an electric vehicle, for which maintainability is excellent.　This drive unit (100) comprises: a drive controller (20) that supplies power from a battery (19) to a brake device (41); an auxiliary power supply (30) that stores the power supplied from the battery (19); and a switching unit (40) that switches the source for supplying power to the brake device (41) to either the battery (19) or the auxiliary power supply (30).

Description

Drive unit and electric vehicle

[0001] The present disclosure relates to a drive unit and an electric vehicle.

[0002] Conventionally, non-excitation actuated brakes have been used in electric vehicles that have driven wheels (omni-wheels) in the front and driving wheels in the rear and are driven by an electric motor. In electric vehicles that use such non-excitation actuated brakes, if the power supply is interrupted, the brakes are activated and the electric vehicle stops.

[0003] When the power supply is cut off, the brakes of the electric vehicle are activated, locking the drive wheels. In this situation, if a problem occurs, such as the battery running out, the user will be unable to move the electric vehicle, making it difficult to deal with the problem.

[0004] To solve this problem, Patent Document 1 discloses an electric vehicle that can supply power to a non-excitation actuated brake from an external source in order to release the non-excitation actuated brake and enable the electric vehicle to move.

[0005] JP 2014-64619 A

[0006] However, to release the power-off actuation brake externally, the user must prepare an external power source in advance. Furthermore, to deal with the above-mentioned problems, the power-off actuation brake must be released for a certain period of time. To release the power-off actuation brake for a long period of time, a large amount of power must be supplied to the power-off actuation brake, which poses a problem: the user must prepare an external power source (for example, a large number of dry batteries) that can supply a large amount of power in advance.

[0007] Non-limiting examples of the present disclosure contribute to providing a drive unit and an electric vehicle that are easy to maintain.

[0008] A drive unit according to one embodiment of the present disclosure includes a drive controller that supplies power from a battery to a brake device, an auxiliary power source that stores the power supplied from the battery, and a switching unit that switches the power supply source to the brake device to either the battery or the auxiliary power source.

[0009] An electric vehicle according to an embodiment of the present disclosure includes the drive unit described above.

[0010] According to an embodiment of the present disclosure, a drive unit and an electric vehicle that are easy to maintain can be provided.

[0011] Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features.

[0012] 1 is a perspective view of an electric vehicle according to a first embodiment, seen diagonally from the front left; 2 is a perspective view showing a drive wheel unit of an electric vehicle according to the first embodiment; 3 is a diagram showing a schematic configuration of a drive unit according to the first embodiment; 4 is a diagram showing an example of a circuit configuration of a switching unit according to the first embodiment; 5 is a flowchart related to a switching operation of a power supply source according to the first embodiment; 6 is a diagram showing a schematic configuration of a drive unit according to a second embodiment; 7 is a diagram showing an example of a circuit configuration of a brake unit of a safety controller according to the second embodiment; 8 is a flowchart related to safe driving control according to the second embodiment; 9 is a diagram showing a schematic configuration of a drive unit according to a third embodiment; 10 is a flowchart related to control of a hand detection sensor according to the third embodiment;

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the arrangement and connection of components shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not recited in independent claims will be described as optional components.

[0014] Furthermore, each drawing is a schematic diagram and is not necessarily a precise illustration. In each drawing, substantially the same components are denoted by the same reference numerals, and redundant explanations will be omitted or simplified.

[0015] The electric vehicle disclosed herein can be used, for example, as a mobile robot that transports items outdoors, indoors, in facilities, on private property, etc., or as the running part of an electric wheelchair that people ride in to move around outdoors, indoors, in facilities, on private property, etc.

[0016] First Embodiment An electric vehicle 1 will be described with reference to Figures 1 and 2. Figure 1 is a perspective view of an electric vehicle according to the first embodiment, as seen obliquely from the front left. Figure 2 is a perspective view showing a drive wheel unit of the electric vehicle 1 according to the first embodiment.

[0017] As shown in FIG. 1 , the electric vehicle 1 has a vehicle body 2 and a main body 3 .

[0018] The body section 2 has a plurality of frames 10, a drive wheel unit 11 including a drive wheel tire 11a and a motor 11b, a driven wheel unit 12 including a driven wheel 12a, a control unit 13, a battery unit 14 that supplies power to the motor 11b, and a detection unit 15 that detects surrounding objects when moving autonomously, and has functions related to the movement of the electric vehicle 1.

[0019] The drive wheel unit 11 may be a crawler or a legged robot. The control unit 13 has a single unit consisting of a motor control unit, a power conversion supply board, and a safety board. The main body 3 has a loading function, and examples of the main body 3 include a storage structure for transporting items and a chair for people to ride on. Note that the main body 3 is not limited to the above examples. Furthermore, the main body 3 does not have to have a loading function, and the main body 3 may not even exist.

[0020] The electric vehicle 1 has at least one pair of left and right drive wheel units 11 and one or more pair of left and right driven wheel units 12. It is desirable that there be one pair of left and right drive wheel units 11, but the electric vehicle 1 may have two or more pairs of driven wheel units 12, not just one pair of left and right drive wheel units 12.

[0021] When the electric vehicle 1 has four wheels, it is desirable that the driven wheel unit 12 is on the front wheel side and the driving wheel unit 11 is on the rear wheel side, but the reverse is also possible. The number of wheels of the driving wheel unit 11 and the driven wheel unit 12 is not limited to two, and may be one wheel or three or more wheels.

[0022] The electric vehicle 1 also includes a first switching device 42. Details of the first switching device 42 will be described later.

[0023] As shown in Figure 2, the drive wheel unit 11 has a drive wheel tire 11a, a motor 11b, a reducer 11c, a drive wheel suspension first link 11d, a drive wheel suspension second link 11e, a drive wheel suspension spring 11f, a drive wheel suspension shaft 11g, a drive wheel stopper 11h, and a drive wheel suspension spring bearing portion 11i, and is fastened to the frame 10 by a drive wheel unit fastening portion (not shown).

[0024] However, the reducer 11c may not be necessary depending on the specifications of the motor 11b, or the motor 11b and the reducer 11c may be integrated. The motor 11b may be equipped with a brake 11j. Furthermore, a damper may be provided as necessary.

[0025] The first drive wheel suspension link 11d and the second drive wheel suspension link 11e are connected by a drive wheel suspension shaft 11g, and the second drive wheel suspension link 11e swings around the drive wheel suspension shaft 11g (swing shaft).

[0026] At this time, the drive wheel suspension shaft 11g is arranged in a direction perpendicular to the fore-and-aft direction of the vehicle body, that is, parallel to the left-and-right direction of the vehicle body, and the drive wheel suspension second link 11e swings only within a plane parallel to the plane consisting of the up-and-down direction and the fore-and-aft direction of the vehicle body.

[0027] The second drive wheel suspension link 11e has two plates connected by a drive wheel suspension shaft 11g with the first drive wheel suspension link 11d in between. A drive wheel suspension spring bearing 11i is fastened to the two plates of the second drive wheel suspension link 11e by a fastening shaft.

[0028] One end of the drive wheel suspension spring 11f is connected to the drive wheel suspension first link 11d, and the other end is connected to the drive wheel suspension second link 11e via the drive wheel suspension spring bearing portion 11i.

[0029] The configuration of the drive unit 100 will be described with reference to Fig. 3. Fig. 3 is a diagram showing a schematic configuration of the drive unit 100 according to the first embodiment. The drive unit 100 shown in Fig. 3 corresponds to either the left or right drive wheel unit 11. The drive unit 100 is provided for each of the left and right drive wheel units 11.

[0030] The drive unit 100 includes a drive controller 20, an auxiliary power supply 30, and a switching unit 40. The drive unit 100 receives power from a battery 19 and drives an electric motor 29 and a brake device 41.

[0031] The drive controller 20 includes a control unit 21 , a power supply unit 22 , a drive unit 23 , and a brake unit 24 .

[0032] The control unit 21 controls the functional blocks of the drive controller 20 such as the power supply unit 22, the drive unit 23, and the brake unit 24.

[0033] The power supply unit 22 is controlled by the control unit 21 and supplies power from the battery 19 to the drive unit 23 .

[0034] The drive unit 23 drives the electric motor 29. The electric motor 29 is a power source for the electric vehicle 1. For example, the drive unit 23 may include a power regeneration inverter. In this case, the power regeneration inverter stores regenerated power (power converted from kinetic energy) obtained from the motor generator of the electric motor 29 in a recovered power storage device (not shown).

[0035] The auxiliary power supply 30 includes a charge / discharge control unit 31 , a power storage unit 32 , a charge unit 33 , and a discharge unit 34 .

[0036] The charge / discharge control unit 31 controls the charging / discharging process of the auxiliary power supply 30. For example, the charge / discharge control unit 31 controls the power supplied to the switching unit 40.

[0037] The power storage unit 32 stores the power supplied from the charging unit 33. The power storage unit 32 is, for example, an electric double layer capacitor that has a wide operating temperature range and is less susceptible to deterioration due to charging and discharging.

[0038] The charging unit 33 stores the power supplied from the battery 19 in the power storage unit 32 .

[0039] The discharge unit 34 discharges the power stored in the power storage unit 32. For example, the power discharged from the discharge unit 34 is supplied to the switching unit 40.

[0040] The output voltage output from the discharge unit (+) 34a to the brake device 41 is preferably set lower than the output voltage output from the battery 19 to the brake device 41. In other words, the output voltage of the auxiliary power supply 30 is preferably lower than the output voltage of the battery 19.

[0041] As a result, the supply of power from the battery 19 to the brake device 41 takes priority over the supply of power from the auxiliary power supply 30 to the brake device 41. As a result, the frequency of use of the auxiliary power supply 30 decreases, and deterioration of the auxiliary power supply 30 due to charging and discharging can be suppressed.

[0042] The switching unit 40 is a switching means for switching the power supply source that supplies power to the braking device 41. The switching unit 40 switches the power supply source that supplies power to the braking device 41 between the battery 19 and the auxiliary power supply 30.

[0043] The electric motor 29 is controlled by the control unit 21 and drives the drive wheel unit 11 .

[0044] The brake device 41 is a non-excitation operated brake device. The brake device 41 is activated while the supply of power is cut off. On the other hand, the brake device 41 is released while power is being supplied. Therefore, while power is being supplied to the brake device 41, the user can push the electric vehicle 1 by hand to move it.

[0045] When the speed of the electric vehicle 1 increases due to the user's manual pushing operation, the electric motor 29 operates as a generator. The electric power generated by this manual pushing operation by the user can be stored in the recovered power storage device described above and supplied to the brake device 41, for example.

[0046] The first switching device 42 is a device that switches the on state or the off state of the switching unit 40. The first switching device 42 also serves to notify the drive controller to stop the operation of the electric motor 29 and release the brake, and to notify the auxiliary power supply 30 to switch from charging to discharging.

[0047] When the first switching device 42 is in the OFF state, the drive controller 20 supplies the power of the battery 19 to the electric motor 29 and the brake device 41. When the first switching device 42 is in the ON state, the auxiliary power supply 30 supplies the power stored in the power storage unit 32 to the brake device 41.

[0048] The first switching device 42 is a normally open switch that is normally open and is turned on by a user's operation. The first switching device 42 is, for example, configured as an alternate switch.

[0049] The circuit of the switching unit 40 will be outlined with reference to Fig. 4. Fig. 4 is a diagram showing an example of the circuit configuration of the switching unit 40 according to the first embodiment.

[0050] The switching unit 40 includes a transistor Q11, diodes D11 and D12, and a resistor R11.

[0051] The transistor Q11 is an element equivalent to a switch that switches whether or not power is supplied from the discharge section (+) 34a to the brake device (+) 41a.

[0052] For example, the transistor Q11 is a PNP bipolar junction transistor, the emitter of which is connected to the discharge terminal (+) 34a, the collector of which is connected to the brake device (+) 41a via a diode D12, and the base of which is connected to a resistor R11.

[0053] The transistor Q11 may be a semiconductor switch such as a field effect transistor (FET), an insulated gate bipolar transistor, or an intelligent power switch (IPS).

[0054] The resistor R11 is an element that protects the transistor Q11 and stabilizes its operation. One end of the resistor R11 is connected to the base of the transistor Q11, and the other end is connected to the first switching device 42.

[0055] Diodes D11 and D12 act as rectifiers and control the flow of current.

[0056] The anode of the diode D11 is connected to the brake section (+) 24a, and the cathode is connected to the brake device (+) 41a and the cathode of the diode D12, the anode of which is connected to the emitter of the transistor Q11.

[0057] The first switching device 42 is a switch for electrically connecting or disconnecting the base of the transistor Q11 to the brake section (-) 24b, the discharge section (-) 34b, and the brake device (-) 41b, which are all grounded.

[0058] As described above, since the first switching device 42 is a normally open switch, the transistor Q11 is normally in the off state. Therefore, no power is supplied to the brake device (+) 41a from the brake section (+) 24a. Since the brake device 41 is a non-excitation operated brake, the brake operates while no power is supplied.

[0059] On the other hand, when the user operates the first switching device 42 to turn the switch on, the base of the transistor Q11 is connected to the brake section (-) 24b, the discharge section (-) 34b, and the brake device (-) 41b, and the base of the transistor Q11 is grounded (0 V is input), which turns the transistor Q11 on and enables voltage to be supplied from the discharge section (+) 34a to the brake device (+) 41a.

[0060] When transistor Q11 is on, the brake device (+) 41a is connected to the brake section (+) 24a and the discharge section (+) 34a via diodes D11 and D12. Due to the rectifying action of diodes D11 and D12, the brake device (+) 41a is supplied with voltage from the larger of the output voltage V24 of the brake section (+) 24a or the output voltage V34 of the discharge section (+) 34a.

[0061] Next, the operation of switching the power supply source that supplies power to the brake device 41 will be described with reference to Fig. 5. Fig. 5 is a flowchart relating to the operation of switching the power supply source according to the first embodiment.

[0062] 5 is executed when the first switching device 42 is switched from an off state to an on state. Specifically, the first switching device 42 is switched from an off state to an on state by a switch operation by the user.

[0063] The drive unit 100 stops the supply of power to the drive section 23 and supplies power to the brake device 41 (S11). This releases the brake of the electric vehicle 1, allowing the user to push the electric vehicle 1 by hand and move it.

[0064] Then, the drive unit 100 switches the auxiliary power supply 30 from charging to discharging (S12).

[0065] Next, if the voltage of the battery 19 is greater than the voltage of the auxiliary power supply 30 (YES in S13), the drive unit 100 supplies power from the battery 19 to the brake device 41 (S14), and the flow proceeds to the processing of S18.

[0066] If the voltage of the battery 19 is lower than the voltage of the auxiliary power supply 30 (NO in S13) and the voltage of the auxiliary power supply 30 is higher than the voltage generated by the user's manual push operation (YES in S15), the drive unit 100 supplies power from the auxiliary power supply 30 to the brake device 41 (S16), and the flow proceeds to processing in S18.

[0067] On the other hand, if the voltage of the battery 19 is lower than the voltage of the auxiliary power supply 30 (NO in S13), and if the voltage of the auxiliary power supply 30 is lower than the voltage generated by the user's manual pushing operation (NO in S15), the drive unit 100 supplies the power generated by the user's manual pushing operation to the brake device 41 (S17), and the flow proceeds to processing in S18.

[0068] Thereafter, if the first switching device 42 is not in the OFF state (NO in S18), the flow returns to the processing in S13.

[0069] If the first switching device 42 is in the ON state (YES in S18), this flow ends.

[0070] The electric vehicle 1 of the first embodiment is configured such that, when the supply of power is interrupted, in addition to the battery 19, power can be supplied to the brake device 41 from the chargeable and dischargeable auxiliary power supply 30 and from power generated by the user's manual push operation. The user can operate the first switching device 42 to supply power to the brake device 41 and release the brakes of the electric vehicle 1. This improves the maintainability of the electric vehicle 1.

[0071] Second Embodiment The configuration of a drive unit 200 according to a second embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram showing a schematic configuration of a drive unit 200 according to the second embodiment. Note that components that are substantially the same as those in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0072] The drive unit 200 according to the second embodiment includes a safety controller 50 .

[0073] The safety controller 50 includes a control unit 51 , a power supply unit 52 , a detection unit 53 , a speed calculation unit 54 , a speed determination unit 55 , and a brake unit 56 .

[0074] The control unit 51 controls the power supply unit 52, the detection unit 53, the speed calculation unit 54, the speed determination unit 55, the brake unit 56, and the like.

[0075] The power supply unit 52 is controlled by the control unit 51 and supplies power from the battery 19 to the power supply unit 52, the detection unit 53, the speed calculation unit 54, the speed determination unit 55, the brake unit 56, and the like.

[0076] The power supply unit 52 is connected to the cathode of a diode D21, and the anode of the diode D21 is connected to the battery 19. The power supply unit 52 is also connected to the cathode of a diode D22, and the anode of the diode D22 is connected to the auxiliary power supply 30. Therefore, the power supply unit 52 is supplied with power from either the battery 19 or the auxiliary power supply 30, whichever has the higher supply voltage.

[0077] The detection unit 53 is connected to a detection sensor 59. For example, the detection sensor 59 is a sensor for acquiring environmental information around the electric vehicle 1. When the detection sensor 59 detects an object that could be an obstacle around the electric vehicle 1, it transmits an obstacle detection signal to the detection unit 53. The detection sensor 59 is, for example, a Lidar, a TOF sensor, a camera, an ultrasonic sensor, an infrared sensor, or the like.

[0078] The speed calculation unit 54 is connected to the speed information acquisition device 28. For example, the speed calculation unit 54 acquires speed information relating to the speed at which the electric vehicle 1 can travel or stop safely, based on the current traveling speed of the electric vehicle 1.

[0079] The speed determination unit 55 determines a stopping range within which the electric vehicle 1 can be stopped safely, based on the environmental information acquired by the detection unit 53 and the speed information acquired by the speed calculation unit 54, and determines whether the electric vehicle 1 is within the stopping range. For example, the stopping range varies depending on the weight of the electric vehicle 1.

[0080] The brake unit 56 is connected to the electric motor 29. When the speed determination unit 55 determines that the electric vehicle 1 is within a stopping range, the brake unit 56 slows down the moving speed of the electric vehicle 1. For example, the brake unit 56 applies a short brake. Furthermore, when the speed determination unit 55 determines that the electric vehicle 1 is moving at a speed equal to or greater than a threshold value, the brake unit 56 may slow down the moving speed of the electric vehicle 1.

[0081] The circuit configuration of brake unit 56 will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of the circuit configuration of brake unit 56 of safety controller 50 according to the second embodiment.

[0082] The brake unit 56 includes transistors Q21, Q22, and Q23, and resistors R21a, R21b, R22a, R22b, R23a, and R23b.

[0083] The brake unit 56 receives a power supply voltage from the brake unit (+) 56a, and the brake unit (-) 56b is grounded.

[0084] The source of the transistor Q21 is connected to the brake (-) 56b and one end of the resistor R21b. The drain of the transistor Q21 is connected to the motor (U phase) 29a. The gate of the transistor Q21 is connected to one end of the resistor R21a and the other end of the resistor R21b. The other end of the resistor R21a is connected to the brake (+) 56a.

[0085] The source of transistor Q22 is connected to brake section (-) 56b and one end of resistor R22b. The drain of transistor Q22 is connected to motor (V phase) 29b. The gate of transistor Q22 is connected to one end of resistor R22a and the other end of resistor R22b. The other end of resistor R22a is connected to brake section (+) 56a.

[0086] The source of transistor Q23 is connected to brake section (-) 56b and one end of resistor R23b. The drain of transistor Q21 is connected to motor (W phase) 29c. The gate of transistor Q23 is connected to one end of resistor R23a and the other end of resistor R23b. The other end of resistor R23a is connected to brake section (+) 56a.

[0087] The gates of the transistors Q21, Q22, and Q21 are connected to the brake section (+) 56a via resistors R21a, R22a, and R23a.

[0088] When the output voltage of the brake (+) 56a reaches a predetermined value or higher, the transistors Q21, Q22, and Q23 are turned on, and the electric motor (U phase) 29a, the electric motor (V phase) 29b, and the electric motor (W phase) 29c are electrically connected to the brake (-) 56b. As a result, the brake 56b erases any remaining charge in the coil of the electric motor 29, thereby decelerating the electric motor 29.

[0089] An example of safe driving control will be described with reference to Fig. 8. Fig. 8 is a flowchart relating to safe driving control according to the second embodiment.

[0090] 8 is executed when the first switching device 42 is changed from an off state to an on state. Specifically, the first switching device 42 is changed from an off state to an on state by a switch operation by the user.

[0091] Drive unit 200 controls auxiliary power supply 30 to switch from charging to discharging (S21). As a result, power is supplied from auxiliary power supply 30 to safety controller 50.

[0092] The drive unit 200 determines whether the electric vehicle 1 is within a stopping range (S22). If the drive unit 200 determines that the electric vehicle 1 is within a stopping range (YES in S22), it decelerates the electric vehicle 1 (S23) and determines whether a predetermined time has elapsed (S24).

[0093] If the predetermined time has not elapsed, the drive unit 200 waits until the predetermined time has elapsed (NO in S24). After the predetermined time has elapsed (YES in S24), the drive unit 200 determines whether the electric vehicle 1 is stopped (S25). If the drive unit 200 determines that the electric vehicle 1 is not stopped (NO in S25), the flow returns to the processing of S22. On the other hand, if the drive unit 200 determines that the electric vehicle 1 is stopped (YES in S25), the flow proceeds to the processing of S26.

[0094] The drive unit 200 executes a process to decelerate the electric vehicle 1 while the electric vehicle 1 is within the stopping range, but if the electric vehicle 1 decelerated by the drive unit 200 moves out of the stopping range, the drive unit 200 may stop the process to decelerate the electric vehicle 1.

[0095] In the process of S22, if the drive unit 200 determines that the electric vehicle 1 is not within the stopping range (NO in S22), the drive unit 200 determines whether the first switching device 42 is in the OFF state (S26). If the drive unit 200 determines that the first switching device 42 is not in the OFF state (NO in S26), the flow returns to the process of S22.

[0096] If the drive unit 200 determines that the first switching device 42 is in the ON state (YES in S26), this flow ends.

[0097] In the second embodiment, when the electric vehicle 1 enters the stopping range, the brake device 41 applies a short brake to slow down the moving speed of the electric vehicle 1. Since the electric vehicle 1 gradually decelerates once it enters the stopping range, the electric vehicle 1 can travel safely.

[0098] <Third embodiment> A schematic configuration of a drive unit 300 according to a third embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram showing a schematic configuration of a drive unit 300 according to the third embodiment. Note that components that are substantially the same as those in the second embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0099] The drive unit 300 according to the third embodiment includes a safety controller 50a.

[0100] Safety controller 50a has a detection sensor control unit 61. Detection sensor control unit 61 is connected to detection sensor 59 and controls the supply of power to detection sensor 59.

[0101] For example, the detection sensor control unit 61 switches the state (on state or off state) of the detection sensor 59 based on the moving speed of the electric vehicle 1 caused by the user's manual pushing operation, which is calculated by the speed calculation unit 54. The detection sensor control unit 61 may switch the detection sensor 59 between the on state and the off state based on the weight of the electric vehicle 1. For example, when the weight of the electric vehicle 1 is greater than a predetermined value, the detection sensor control unit 61 maintains the on state of the detection sensor 59.

[0102] An example of power supply to the detection sensor 59 by the detection sensor control unit 61 will be described with reference to Fig. 10. Fig. 10 is a flowchart showing an example of control of the detection sensor 59 according to the third embodiment.

[0103] 10 is executed when the first switching device 42 is changed from an off state to an on state. Specifically, the first switching device 42 is changed from an off state to an on state by a switch operation by the user.

[0104] Drive unit 300 controls auxiliary power supply 30 to switch from charging to discharging (S31), so that power is supplied from auxiliary power supply 30 to safety controller 50a.

[0105] Thereafter, the drive unit 300 determines whether the speed of the electric vehicle 1 exceeds a threshold value (S32). If the drive unit 300 determines that the speed of the electric vehicle 1 does not exceed the threshold value (NO in S32), the drive unit 300 turns off the power to the detection sensor 59 (S33), and the flow proceeds to the processing of S34.

[0106] If the drive unit 300 determines that the speed of the electric vehicle 1 exceeds the threshold value (YES in S32), the drive unit 300 determines whether the first switching device 42 is in the OFF state (S34). If the drive unit 300 determines that the first switching device 42 is not in the OFF state (NO in S34), the flow returns to the processing of S32.

[0107] If the drive unit 300 determines that the first switching device 42 is in the ON state (YES in S34), this flow ends.

[0108] The threshold value for the process in S32 may be changed depending on the degree of danger when the electric vehicle 1 collides with an obstacle, etc. For example, the threshold value for the moving speed of the electric vehicle 1 may be set to 1 km / h, and the power supply to the detection sensor may be turned off if the moving speed is less than 1 km / h, and turned on if the moving speed is 1 km / h or more.

[0109] In the third embodiment, the power supply of the detection sensor 59 is switched on or off as needed, thereby reducing the power consumption of the drive unit 200. This makes it possible to extend the time that the electric vehicle 1 can be moved by the user's manual push operation using the auxiliary power supply 30. Furthermore, since the capacity of the power storage unit 32 can be reduced, the auxiliary power supply 30 can be made smaller.

[0110] <Fourth embodiment> The configuration of a drive unit 400 according to a fourth embodiment will be described with reference to Fig. 11. Fig. 11 is a diagram showing a schematic configuration of a drive unit 400 according to the fourth embodiment. Note that components that are substantially the same as those in the first to third embodiments are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0111] The drive unit 400 according to the fourth embodiment includes a switching unit 40a, which is connected to a second switching device 71 in addition to a brake device 41 and a first switching device 42.

[0112] The second switching device 71 is a device that controls the brake device 41 based on a user's operation. The second switching device 71 is preferably located in a position that is easy to operate when the user pushes the electric vehicle 1. For example, the second switching device 71 is a normally closed switch that is normally closed and is turned off by a user's operation. For example, the second switching device 71 is configured as a momentary switch.

[0113] The circuit configuration of the switching unit 40a will be described with reference to Fig. 12. Fig. 12 is a diagram showing an example of the circuit configuration of the switching unit 40a according to the fourth embodiment.

[0114] The switching unit 40a includes transistors Q31 and Q32, diodes D31 and D32, and resistors R31 and R32. The switching unit 40a also includes the same switching unit 40 as in the first embodiment.

[0115] The transistor Q31 is an element equivalent to a switch that switches whether or not power is supplied from the brake section (+) 24a to the brake device (+) 41a.

[0116] The transistor Q32 and the transistor Q11 are elements equivalent to a switch that switches whether or not power is supplied from the discharge section (+) 34a to the brake device (+) 41a.

[0117] The transistors Q31 and Q32 are PNP bipolar transistors, just like the transistor Q11, but may also be semiconductor switches such as field effect transistors or insulated gate bipolar transistors.

[0118] The emitter of the transistor Q31 is connected to the brake section (+) 24a, the collector is connected to the brake device (+) 41a via a diode D11, and the base of the transistor Q31 is connected to a resistor R31.

[0119] The resistor R31 is an element that protects the transistor Q31 and stabilizes its operation. One end of the resistor R31 is connected to the base of the transistor Q31, and the other end is connected to the anode of the diode D31.

[0120] The emitter of the transistor Q32 is connected to the discharge part (+) 34a, the collector is connected to the emitter of the transistor Q11, and the base of the transistor Q32 is connected to the resistor R32.

[0121] The resistor R32 is an element that protects the transistor Q32 and stabilizes its operation. One end of the resistor R32 is connected to the base of the transistor Q32, and the other end is connected to the anode of the diode D32.

[0122] The cathodes of diodes D31 and D32 are connected to a second switching device 71. Diodes D31 and D32 function as rectifiers to control the flow of current.

[0123] The second switching device 71 is a normally closed switch and is normally on. In this case, when the first switching device 42 is turned on by a user's operation, the transistors Q11, Q31, and Q32 are turned on, so that the brake device 41 is supplied with power from either the brake section (+) 24a or the discharge section (+) 34a, whichever has the larger output voltage. When the first switching device 42 is turned off by a user's operation, the transistor Q11 is turned off and the transistors Q31 and Q32 are turned on, so that the brake device 41 is supplied with power from the brake section (+) 24a.

[0124] On the other hand, when the second switching device 71 is turned off by a user operation, the transistors Q31 and Q32 are turned off, and therefore, regardless of the on or off state of the transistor Q11, no power is supplied to the brake device 41. In other words, when the second switching device 71 is turned off, the power supply to the brake device 41 is cut off regardless of the state of the first switching device 42.

[0125] In the fourth embodiment, the user can apply the brakes to the electric vehicle 1 at any timing by operating the second switching device 71. This improves the safety of movement of the electric vehicle 1 when the user pushes it manually.

[0126] <Summary of the embodiment> As described above, the drive unit of the present embodiment includes a drive controller that supplies power from a battery to a brake device, an auxiliary power supply that stores the power supplied from the battery, and a switching unit that switches the power supply source to the brake device to either the battery or the auxiliary power supply.

[0127] With this configuration, when the supply of power to the electric vehicle 1 is cut off, the drive unit 100 can supply power generated by the battery 19, the auxiliary power supply 30, and the user's manual push operation to the brake device 41 to release the brake, thereby improving the maintainability of the electric vehicle 1.

[0128] In the above-described embodiments, the notation "... part" used for each component may be replaced with other notations such as "... circuit," "... assembly," "... device," "... unit," or "... module."

[0129] Although the embodiments have been described above with reference to the drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims. It is understood that such modifications or alterations also fall within the technical scope of the present disclosure. Furthermore, the components of the embodiments may be combined in any manner without departing from the spirit of the present disclosure.

[0130] The present disclosure is useful as a drive unit and an electric vehicle.

[0131] REFERENCE SIGNS LIST 1 electric vehicle 2 vehicle body 3 main body 10 frame 11 drive wheel unit 11a drive wheel tire 11b motor 11c reducer 11d drive wheel suspension first link 11e drive wheel suspension second link 11g drive wheel suspension shaft 11h drive wheel stopper 11i receiving portion 11j brake 12 driven wheel unit 12a driven wheel 13 control unit unit 14 battery unit 15 detection unit unit 19 battery 20 drive controller 21 control unit 22 power supply unit 23 drive unit 24 brake unit 28 speed information acquisition device 29 electric motor 30 auxiliary power supply 31 charge / discharge control unit 32 power storage unit 33 charging unit 34 discharging unit 40 switching unit 41 brake device 42 first switching device 71 second switching device

Claims

1. A drive unit comprising: a drive controller that supplies power from a battery to a brake device; an auxiliary power source that stores the power supplied from the battery; and a switching unit that switches the power supply source to the brake device to either the battery or the auxiliary power source.

2. A drive unit as described in claim 1, wherein the switching unit supplies the power from the battery to the brake device when the first switching device is turned off by a user's operation, and supplies the power from the auxiliary power source to the brake device when the first switching device is turned on by the user's operation.

3. The drive unit according to claim 1, wherein the switching unit supplies the electric power from the battery to the brake device when the voltage of the battery is higher than the voltage of the auxiliary power supply.

4. The drive unit according to claim 1, wherein the switching unit supplies the electric power from the auxiliary power supply to the brake device when the voltage of the battery is lower than the voltage of the auxiliary power supply.

5. The drive unit according to claim 1, wherein the switching unit supplies the electric power generated by the manual push operation to the brake device when the voltage of the battery is lower than the voltage of the auxiliary power supply and the voltage generated by the manual push operation is higher than the voltage of the auxiliary power supply.

6. A drive unit as described in claim 1, further comprising: a detection unit that acquires environmental information about the surroundings of the vehicle from a detection sensor; a speed calculation unit that acquires speed information about the vehicle; and a speed determination unit that determines whether the vehicle is located within a stopping range where it can be stopped safely, based on the environmental information and the speed information.

7. The drive unit according to claim 6, further comprising a detection sensor control unit that switches the power supply of the detection sensor between an on state and an off state based on the speed information.

8. The drive unit according to claim 7, wherein the detection sensor control unit switches the detection sensor between an on state and an off state based on the weight of the vehicle.

9. The drive unit according to claim 1, wherein the switching unit cuts off the power supply to the brake device and activates the brake device when a second switching device is operated by a user.

10. An electric vehicle comprising a drive unit according to any one of claims 1 to 9.

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