JP5887918B2 - Vehicle braking device - Google Patents

Description

  The present invention relates to a vehicle braking device, and more particularly to a vehicle braking device that supplies electric power to a permanent magnet synchronous motor disposed on a wheel to apply a braking force to the wheel.

  As a vehicle braking device, a hydraulic braking device that performs hydraulic braking is generally used, but regenerative braking by an electric motor is used in a recent electric vehicle or a so-called hybrid vehicle. For example, Patent Literature 1 below discloses a braking force control device that creates a margin for motor torque on both the regeneration side and the power running side and expands the control range of the motor torque. In Patent Document 2, cooperative control of regenerative braking and hydraulic braking is performed. On the other hand, Patent Document 3 below discloses an electric brake device that converts a rotation of an electric motor into a linear motion to propel a piston and presses a friction pad against a disk rotor to generate a braking force. Thus, as a braking device in a vehicle equipped with a driving electric motor, in addition to regenerative braking (regenerative braking) by an electric motor, friction braking by mechanical brake means such as a hydraulic brake device or the above-described electric braking device is possible. Are used together.

  Further, Patent Document 4 below proposes to perform reverse-phase braking by exciting the motor so as to reversely rotate, but this is a general braking means in an induction motor that does not use a permanent magnet. Yes, it is used in railway vehicles. In other words, in railway vehicles (electric vehicles), an electric vehicle control device that performs pure electric braking or all electric braking by performing electric braking or stop braking in addition to regenerative braking is proposed in order to be able to stop only by induction motors. In addition to regenerative braking, reverse phase braking is used. For example, Patent Document 5 below discloses a reverse-phase electric brake that obtains a braking force by switching from a forward brake to a reverse power line as the speed decreases. However, in an actual railway vehicle, friction braking is still used together, and for example, an air brake device is also mounted.

  As a braking device for use in the above-described electric vehicle or hybrid vehicle, generally, a permanent magnet synchronous motor that includes a rotor having a permanent magnet and a stator that rotationally drives the rotor, and connects the rotor to each wheel of the vehicle; Power storage means such as a battery for supplying power to the permanent magnet synchronous motor to excite the stator is provided, and the permanent magnet synchronous motor is configured to suppress the rotation of the wheel. In particular, the permanent magnet is embedded in the rotor. An embedded permanent magnet field type synchronous motor (referred to as IPM) is used. Furthermore, an in-wheel motor (referred to as IWM) in which a rotor and a stator of an electric motor are housed in a wheel of a wheel has been proposed, and for example, disclosed in Patent Document 6 below, this is also used in combination with friction braking, The wheel is equipped with a hydraulic friction brake device in addition to the electric motor. When this type of electric motor braking device is mounted on one of the front side and the rear side of the vehicle, as described in Patent Document 7, it is generally mounted on a wheel on the rear side of the vehicle.

JP 2007-106385 A Japanese Patent Laid-Open No. 11-4504 JP 2003-287069 A JP 2004-187445 A JP-A-11-234804 JP 2007-196904 A JP-A-9-238405

  As described above, in railway vehicles (electric vehicles), a technique that can be stopped only by an induction motor has attracted attention. However, in an electric vehicle or a hybrid vehicle, in addition to regenerative braking by a permanent magnet synchronous motor, hydraulic friction A friction brake by a brake device is also used, and a hydraulic friction brake device is indispensable in order to bring a wheel into a stopped state even in an in-wheel motor. This is an impediment to the reduction of the unsprung load, and is limited to downsizing, and it is inevitable that the apparatus becomes expensive. In addition, a braking device using an electric motor is generally mounted on a wheel behind the vehicle. However, since the heat radiation effect is lower at the rear of the vehicle than at the front, a separate large cooling device is required, and the entire device becomes large.

  Therefore, in the present invention, a permanent magnet synchronous motor is disposed on the wheel side having a high heat dissipation effect, and the wheel is stopped only by control of the permanent magnet synchronous motor without requiring a friction brake device on the wheel side. It is an object of the present invention to provide a braking device for a vehicle that can apply braking force smoothly and reliably.

In order to achieve the above object, the present invention comprises a rotor having a permanent magnet and a stator for rotationally driving the rotor, the rotor is connected to a wheel, the stator is excited, and an excitation brake is applied to the wheel. Thus, the permanent magnet synchronous motor that applies a braking force to the wheel is configured to be housed inside a wheel that constitutes the wheel and is not provided with a friction brake device in front of the vehicle. .

In particular, in the above configuration, a planetary gear speed reduction mechanism is provided on the shaft of the permanent magnet synchronous motor to reduce the rotation of the rotor, an oil pump is provided on the planetary speed reduction mechanism side to be rotated at a reduced speed, It may be configured to be housed inside .

In the above braking system, disposed in a housing for housing the permanent magnet synchronous motor, and those with lubrication cooling means for cooling with a self lubricating with respect to the permanent magnet synchronous motor in said housing, said The housing may be accommodated inside the wheel .

Since this invention is comprised as mentioned above, there exist the following effects. That is, the apparatus of the present invention is configured to supply electric power to a permanent magnet synchronous motor disposed on a wheel in front of the vehicle having a high heat dissipation effect and apply a braking force to the wheel. Without requiring a brake device, the wheel can be stopped smoothly and reliably only by control of the permanent magnet synchronous motor. In this case, since the permanent magnet synchronous motor is provided inside the wheel in front of the vehicle, a good cooling effect can be obtained.

For example, in the above configuration, the braking force equivalent to that in the high rotation region can be generated even in the low rotation region of the wheel by the excitation brake, and the vehicle can be stopped smoothly and reliably.

Further, according to the present invention, the permanent magnet synchronous motor can be properly lubricated and cooled by the lubricating cooling means, and the entire braking device can be further reduced in size and weight.

It is a lineblock diagram showing the vehicles carrying the brake equipment concerning one embodiment of the present invention. It is a block diagram which shows the main structural examples of the braking device which concerns on one Embodiment of this invention. It is sectional drawing of the wheel in embodiment which applied this invention to the in-wheel motor. It is a graph which shows the relationship between the rotation speed and braking torque in one Embodiment of this invention. It is a wave form diagram which shows the torque characteristic of the permanent magnet permanent magnet synchronous motor in one Embodiment of this invention, and the relationship between the rotor angle at the time of each control, and an electric current. It is a flowchart which shows the process of the braking control in one Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an overall configuration of a vehicle braking apparatus according to an embodiment of the present invention, and an embedded permanent magnet field synchronous motor IPM (hereinafter simply referred to as a permanent magnet synchronous motor IPM) is omitted in FIG. However, it comprises a rotor having a permanent magnet and a stator for rotationally driving the rotor, and the rotor is connected to the wheels (FL, FR) and is configured to rotate integrally. In FIG. 1, the wheel FL indicates the front left wheel as viewed from the driver's seat, the wheel FR indicates the front right side, the wheel RL indicates the rear left side, and the wheel RR indicates the rear right wheel.

  The present embodiment is a rear wheel drive system in which wheels (RL and RR) at the rear of the vehicle are driven by a prime mover (for example, an internal combustion engine) ENG. The wheels (FL and FR) in front of the vehicle have an in-wheel motor IWM that includes a motor generator (indicated by MG in FIG. 3) using a permanent magnet synchronous motor IPM as means for driving and braking each wheel. The permanent magnet synchronous motor IPM is driven for each wheel, and a driving force can be applied to each wheel, and a braking force by an excitation brake can be applied. That is, as shown in FIG. 1, conversion control means IV for converting the power of the power supply means PS including the power storage means BT to excite the stator and controlling the rotation of the rotor, and the rotor according to the control of the conversion control means IV In-phase excitation control means PEB that excites the stator and applies an excitation brake to each wheel in the same phase as the excitation of the stator in the rotational direction of the motor, and supplies the power of the power supply means PS to the permanent magnet synchronous motor IPM. The braking force is applied to FL and FR).

  In this embodiment, the permanent magnet synchronous motor IPM is disposed in front of the driver's seat (not shown) of the vehicle, and a good cooling effect is obtained. It is preferable that a hybrid vehicle is constituted by the motors ENG and MG and the power source means PS described above, and the electric power accumulated in the electric power accumulation means BT is supplied to the permanent magnet synchronous motor IPM and used for driving the vehicle and starting the engine. In addition, a simple engine drive may be used without using MG.

  FIG. 2 shows a specific configuration example of the power supply means PS (power storage means BT), conversion control means IV, in-phase excitation control means PEB, and the like. The battery B1 serves as the power storage means BT and the booster serves as the boost means RV. An inverter C1 is provided as the circuit C2 and the conversion control means IV, and these are controlled by the electronic control unit ECU, and the function as the above-mentioned common-phase excitation control means PEB is executed in addition to the control of the driving force for each wheel. The permanent magnet synchronous motor IPM of the present embodiment has three-phase coils of U, V, and W, the excitation current to each phase coil is PWM-controlled by the electronic control unit ECU, and functions as an electric motor during driving. During braking, it functions as a generator and charges the battery B1 via the inverter C1. The battery B1 is a secondary battery, but may be a fuel cell, and a large capacity capacitor may be used as the power storage means BT. The inverter C1 converts the DC voltage of the battery B1 into an AC voltage according to the PWM signal, and controls to output a desired torque from the permanent magnet synchronous motor IPM, and generates AC of the permanent magnet synchronous motor IPM during regenerative braking. The voltage is converted into a DC voltage and controlled to charge the battery B1, and is controlled for each of the U, V, and W phase coils.

  The wheels FL, FR, RL, and RR are provided with wheel speed sensors (not shown), which are connected to the electronic control unit ECU, and a pulse proportional to the rotational speed of each wheel, that is, the wheel speed. A plurality of wheel speed signals Sw are input to the electronic control unit ECU. Further, an accelerator sensor (not shown) that outputs an accelerator signal Sa corresponding to the degree of depression of an accelerator pedal (not shown) by the driver, and a brake signal corresponding to the degree of depression of a brake pedal (not shown) by the driver. A brake pedal sensor (not shown) that outputs Sb, a shift position sensor (not shown) that outputs a shift signal Ss corresponding to the shift position of a transmission (not shown), and the steering of the wheels FL and FR in front of the vehicle A steering angle sensor (not shown) for detecting the angle θ, a yaw rate sensor (not shown) for detecting the yaw rate γ of the vehicle, and currents of the U, V, and W phase coils (Im representatively shown in FIG. 2) A current sensor (not shown) or the like that detects (represents) is connected to the electronic control unit ECU.

  Since the electronic control unit ECU of the present embodiment has a general configuration, it is not shown, but includes a microcomputer including a CPU, a ROM, a RAM, an input / output port and the like connected to each other via a bus. The wheel speed signal Sw, the accelerator signal Sa, the brake signal Sb, the shift signal Ss, the steering angle θ, the yaw rate γ, and the like are each input from the input port to the CPU. In addition, a control signal is output from the output port to the inverter C1 and the like. Thus, in the electronic control unit ECU, in-phase excitation control is performed in which the stator is excited and an excitation brake is applied in phase with the excitation of the stator in the rotational direction of the rotor during driving. Further, at the time of excitation braking, the boosted electric power is supplied to the inverter C1 via the booster circuit C2 to excite the stator.

  In addition, as shown with a broken line in FIG. 2, you may comprise so that the regenerative control which accumulate | stores the regenerative electric power which arises in the permanent magnet synchronous motor IPM in battery B1, and provides a regenerative brake may be performed. In this case, the switching timing from the regenerative brake to the excitation brake is adjusted based on the difference between the regenerative power calculated based on the current Im of each phase coil and the required braking force calculated based on the brake signal Sb or the like. Is done.

  Next, a specific structure of the embodiment in which the permanent magnet synchronous motor IPM is accommodated in the wheel W to constitute the in-wheel motor IWM will be described with reference to FIG. 3. A hub is provided inside the wheel W constituting the wheel. 2 is fixed, and the output shaft 3 is splined to the hub 2. In FIG. 3, the motor generator MG is shown as a means for driving and braking, but this corresponds to the permanent magnet synchronous motor IPM of FIG. 1, and a coil 4c is wound around the stator 4 which is a component thereof. The motor case 10 is fixed inside. A rotor 5 in which a permanent magnet (not shown) is embedded is disposed inside the stator 4 and is supported so as to be rotatable around the central axis of the hub 2.

  Further, a flange portion 5f is formed to extend in the center of the rotor 5, and a sun gear 6 is attached to the flange portion 5f. On the other hand, a ring gear 8 is fixed inside the motor case 10, and a carrier 9 is attached to the planetary gear 7 that meshes with the ring gear 8 and the sun gear 6. The carrier 9 is spline-coupled with the output shaft 3 and is configured so as to rotate integrally with each other, thereby forming a planetary gear reduction mechanism RM (hereinafter simply referred to as a reduction mechanism RM). Thus, the rotation of the rotor 5 by the motor generator MG is transmitted to the output shaft 3 through the sun gear 6, the planetary gear 7, and the ring gear 8, and the wheel W is driven to decelerate and rotate. On the other hand, at the time of vehicle deceleration, the rotational force of the wheel W is transmitted to the rotor 5 contrary to the above.

  A cover 11 and an oil pump cover 12 are fixed to the motor case 10, and an oil pump 13 is built in a housing formed by these. The oil pump 13 constitutes the above-described lubricating cooling means, and is configured to be driven by the carrier 9 to pump up the lubricating oil. That is, in FIG. 3, S indicates the oil level of the lubricating oil reservoir in the housing when the vehicle is stopped, and when the oil pump 13 is driven according to the rotation of the wheel W, the lubricating oil below the oil level S is transferred to the oil pump. 13 is pumped up. The lubricating oil pumped up in this way is provided in the oil passage A formed in the center of the output shaft 3, the oil pump cover 12, and the motor case 10 as shown by arrows in FIG. The oil is supplied to the speed reduction mechanism RM via the oil passages B, C, D and E, and is supplied around the stator 4, and after these are cooled, the oil is returned to the lubricating oil reservoir via the space F in the housing. It is. As described above, the lubricating oil circulates in the housing, so that the motor generator MG is properly self-lubricated and cooled. The motor case 10 is joined at its outer periphery to the upper arm 14 and the lower arm 15 and connected to a vehicle body (not shown) via another suspension member (not shown).

  Regarding the motor generator MG in the case where the permanent magnet synchronous motor IPM is configured to perform regenerative braking and excitation braking, torque characteristics during braking will be described with reference to FIG. First, when a braking request is received from the vehicle running state and the regenerative control state is entered, the rotational speed N decreases while generating the braking torque T as shown by the solid line in FIG. 4 according to the rotational speed at that time. That is, from the constant output region on the right side of FIG. 4 to the constant torque region. When the regenerative control is continued, it is determined that the rotation speed is lower than the predetermined rotation speed (Nc) peculiar to the motor generator MG, and is lower than the predetermined torque (Tt−ΔT) obtained by subtracting the predetermined torque difference ΔT from the target braking torque (Tt) as the target braking force. Then, it is determined that the excitation brake control region (Bpe) has been entered. Thus, in-phase excitation control is performed by the electronic control unit ECU, and the target braking torque (Tt) is maintained as shown by the solid line in FIG. If the rotational speed falls below the predetermined rotational speed (Nc), the braking torque T decreases as shown by the broken line in FIG. 4, so that the actual braking force can be estimated based on the regenerative power at that time. Based on the detection result, it is possible to determine the transition to the excitation brake control region (Bpe).

  Here, the operation principle at the time of regenerative braking and excitation braking by the permanent magnet synchronous motor IPM will be described with reference to FIG. FIG. 5 is a waveform diagram showing the torque characteristics of the permanent magnet synchronous motor IPM and the relationship between the rotor angle and current during driving, regenerative braking, and excitation braking. U, V, W in (B) to (D) Indicates each phase current of the three-phase coil. FIG. 5A shows an example of torque characteristics of the permanent magnet synchronous motor IPM, showing the relationship between the energization phase and the output torque when a constant current is applied, and a positive torque range and a negative torque range are alternately generated. Next, FIG. 5B shows a general relationship between the rotor angle during driving (driving) and the drive current, and the motor characteristic of FIG. 5A is energized at the phase with the largest torque (point b). The Conversely, FIG. 5C shows a general relationship between the rotor angle and the regenerative current during regenerative braking, and energization is performed at the phase (c point) where the torque is the smallest in the motor characteristics of FIG. FIG. 5D shows an example of excitation braking. The phase is shifted from that in FIG. 5A (point d), and the voltage is boosted by the booster circuit C2 as necessary to increase the energization current (ΔId). This is the braking continuation current. Thereby, even if the braking force by regenerative braking becomes small, required braking force is ensured by excitation braking.

  The rotation of the wheel W is suppressed by the motor generator MG and the speed reduction mechanism RM, and the braking control is performed until the wheels FL and FR are stopped. An example of this braking control will be described below with reference to FIG. To do. Although description of drive control by the motor generator MG is omitted, any control is repeatedly executed at predetermined time intervals by the electronic control unit ECU of FIG. In FIG. 6, based on a detected brake signal Sb signal from a brake pedal sensor (not shown), a driver's braking request is determined in step 101. If it is determined here that the driver has requested braking, the process proceeds to step 102, where the control proceeds to regenerative control by the motor generator MG, and regenerative braking is started.

  Thus, the rotational speed decreases while generating the regenerative braking torque along the solid line in FIG. As a result, the magnetomotive force generated by the motor generator MG is reduced, and the target braking torque (Tt) cannot be satisfied only by the regenerative braking torque, which falls below the torque (Tt−ΔT) in FIG. If it is determined that [Delta] T) exceeds the predetermined value [alpha], the target braking force cannot be maintained with the regenerative brake alone, so the routine proceeds to step 104, where the above-mentioned common-phase excitation control is performed and the excitation brake is started. In this case, the pole relationship between the poles of the rotor 5 and the stator 4 is maintained at the same distance as that in the driving state, so that a braking force comparable to the driving state can be generated. That is, in the driving state, the excitation to the stator 4 is performed in a form that precedes the rotation of the rotor 5, whereas in the braking state, the rotation of the rotor 5 is excited in the form that precedes the rotation of the rotor 5. A substantially equal braking force can be generated, and a larger braking force can be generated as compared with the case where the reverse phase braking disclosed in Patent Document 4 is applied to the permanent magnet synchronous motor IPM. Further, by maintaining the state in which the rotation of the rotor precedes the excitation, a stable braking force can be obtained, and a large torque pulsation such as reverse phase braking can be avoided.

  When it is determined at step 105 that the rotational speed N has fallen below the predetermined value Kb and the wheels FL and FR are determined to be in a stopped state, the routine proceeds to step 106 where excitation control is stopped and the permanent magnet synchronous motor IPM is locked. The As the locking means, for example, an engaging member (not shown) can be freely engaged with and disengaged from the rotor or a member that rotates integrally with the rotor (for example, the wheel W or a member that is integrally joined thereto). If the wheel is mounted on the above-described housing and thereby configured to prevent the rotation of the wheel W, the stopped state of the wheels FL and FR can be maintained without requiring power supply thereafter.

W wheel IPM permanent magnet synchronous motor PS power supply means BT power storage means IV conversion control means PEB in-phase excitation control means ECU electronic control unit MG motor generator RM planetary gear reduction mechanism 2 hub 3 output shaft 4 stator 5 rotor 10 motor case 11 cover 13 Oil pump

Claims (3)

A rotor having a permanent magnet and a stator for rotationally driving the rotor; the rotor is connected to a wheel; the stator is energized and an excitation brake is applied to the wheel; A braking device for a vehicle, wherein the permanent magnet synchronous motor to be applied is housed in a wheel that constitutes the wheel and is not provided with a friction brake device in front of the vehicle. On the shaft of the permanent magnet synchronous motor, provided with a planetary gear reduction mechanism in which the rotation of the rotor is reduced and rotated,
2. The braking device for a vehicle according to claim 1 , wherein an oil pump is provided on the side of the planetary reduction mechanism that has been decelerated and rotated, and is housed inside the wheel . Lubricating cooling means is provided in the housing for housing the permanent magnet synchronous motor, self-lubricating and cooling the permanent magnet synchronous motor in the housing, and housing the housing in the wheel. braking apparatus for a vehicle according to claim 1 or 2, characterized in that.

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