Parallel hybrid drive for a motor vehicle

Abstract

The invention relates to a parallel hybrid drive for a motor vehicle, to a motor vehicle, to a method for operating a parallel hybrid drive in an all-electric mode, to a method for operating a parallel hybrid drive in a direct drive mode and to a method for operating a parallel hybrid drive in a CVT mode. The parallel hybrid drive (1) for a motor vehicle according to the invention comprises a) an electric machine (2) which can be operated as a motor and as a generator, b) an internal combustion engine (3), c) a drive shaft (4), d) a epicyclic gear (5) comprising - a first shaft (6) which is connected to the electric machine (2), - a second shaft (7) which is connected to the internal combustion engine (3), and - a third shaft (8) which is connected to the drive shaft (4), e) a clutch element (9) which is configured to firmly connect at least two shafts of the epicyclic gear (5) to one another, and f) a first brake element (10) which is configured to prevent the internal combustion engine (3) from rotating in one rotational direction.

Description

Technical Field

[0001] The present invention relates to a parallel hybrid drive for a motor vehicle, a motor vehicle, a method for operating the parallel hybrid drive in all-electric mode, a method for operating the parallel hybrid drive in direct drive mode, and a method for operating the parallel hybrid drive in continuously variable transmission (CVT) mode with continuously variable control range. Background Technology

[0002] A hybrid drive is known from DE10049514B4, which includes a planetary gear, an internal combustion engine, an electric prime mover, and two clutches. Summary of the Invention

[0003] The parallel hybrid drive for motor vehicles according to the present invention includes

[0004] a) An electric motor that can operate as both a motor and a generator.

[0005] b) Internal combustion engine,

[0006] c) Drive shaft,

[0007] d) Epicyclic gears, including

[0008] - The first shaft, which is connected to the motor.

[0009] - The second shaft, which is connected to the internal combustion engine, and

[0010] - The third axis, which is connected to the drive shaft.

[0011] e) A clutch element configured to securely connect at least two shafts of a planetary gear to each other, and

[0012] f) A first braking element, which is configured to prevent the internal combustion engine from rotating in one direction.

[0013] Because the first braking element is configured to prevent the internal combustion engine from rotating in one direction, the drive shaft can be driven independently of the internal combustion engine by means of an electric motor. This enables fully electric propulsion for motor vehicles.

[0014] The first braking element can be configured, for example, to prevent the internal combustion engine from rotating in the rearward direction. The first braking element can be configured to secure the output shaft of the internal combustion engine to the housing of the hybrid drive. The first braking element can, for example, be designed to operate in a frictional engagement or positive-locking manner. The first braking element can be configured to connect the output shaft to the housing in a rotationally fixed manner by its actuation. For example, the first braking element can be closed by actuation. A rotationally fixed connection causes equal rotational motion of the two connected components. Due to intentional or unintentional slippage, there may be differences in rotational speed, but the rotational motion is still considered equal.

[0015] The first braking element can, for example, be configured to switch automatically. This means that the first braking element can automatically close and open. Unlike actively switchable braking elements, this means that no corresponding actuator is needed to actuate the first braking element, and actuation is performed automatically due to the operation of the hybrid drive, for example, based on the corresponding states of the electric motor and the internal combustion engine. Therefore, the hybrid drive can be compact and cost-effective. Furthermore, manual actuation of the braking element is not required. This simplifies the operation of motorized vehicles.

[0016] The first braking element can be configured to automatically lock the output shaft of the internal combustion engine based on a first direction of rotation of the engine. The first braking element can also be configured to automatically release the output shaft of the internal combustion engine based on a second direction of rotation opposite to that of the engine. The first braking element, for example, can be designed as a freewheel, particularly a roller freewheel. An example of a roller freewheel is a ball bearing configured to prevent the shaft mounted thereon from rotating in the first direction of rotation and to prevent it from rotating in the opposite second direction of rotation.

[0017] The first braking element can be alternatively or additionally configured to be actively switchable. For this purpose, the hybrid drive may include a braking actuation element. A purely actively switchable braking element can be simpler and cheaper than a purely automatically switchable braking element because it may have no rotating parts or at least fewer rotating parts. The actively switchable first braking element enables regenerative braking by the electric motor in more states of the hybrid drive. For example, the actively switchable first braking element can also lock the second shaft. The actively switchable first braking element can be configured to prevent rotation of the internal combustion engine in both directions of rotation.

[0018] The output shaft of the internal combustion engine can be fixedly connected to the second shaft in a rotatable manner. For example, the output shaft of the internal combustion engine and the second shaft of the planetary gear can be formed as a single component or welded together or threaded together. Therefore, for example, the first braking element is not used to disconnect or establish the connection between the internal combustion engine and the second shaft of the planetary gear.

[0019] Planetary gears can be configured, for example, as planetary gears. A planetary gear set may consist of only a single planetary gear set. A planetary gear set may be configured, for example, as a negative planetary gear set or a positive planetary gear set. A planetary gear set may include a sun gear shaft, a carrier shaft, and a ring gear shaft. A set of planetary gears may be rotatably mounted on the carrier shaft. Each planetary gear may mesh with, for example, the sun gear shaft and the ring gear shaft. A hybrid drive may lack braking elements and additional clutch elements other than those described herein.

[0020] Preferably, the first shaft of the planetary gear is configured as a ring gear shaft, the second shaft of the planetary gear is configured as a sun gear shaft, and the third shaft of the planetary gear is configured as a carrier shaft. This can produce a favorable gear ratio, especially since electric motors generally operate most efficiently at higher speeds, while internal combustion engines operate most efficiently at relatively lower speeds.

[0021] Preferably, the parallel hybrid drive includes a throttle valve control configured to set the torque of the internal combustion engine at a predetermined speed. The operating speed is determined by means of an electric motor. Particularly preferably, the throttle valve control is configured as a direct mechanical type.

[0022] A direct mechanical throttle valve controller can be provided, for example, via a Bowden cable. The throttle valve controller may include an actuating element. This actuating element can be directly mechanically connected to the throttle valve of the internal combustion engine to regulate the throttle valve. For example, the actuating element can be configured as a rotary handlebar of a small motorcycle with a hybrid drive system. The actuating element can be configured to regulate the torque generated by the internal combustion engine, for example, by controlling the air supply to the internal combustion engine. For this purpose, in the case of a directly mechanically constructed throttle valve controller, the actuating element can be connected to the throttle valve by means of a Bowden cable. For example, the torque generated by the internal combustion engine can be regulated by the driver by actuating the actuating element.

[0023] Therefore, compared to electronically controlled throttle valves, signal monitoring can be simplified or even completely eliminated. Furthermore, throttle valve controllers do not require redundancy and plausibility checks to meet functional safety requirements.

[0024] The motor can, for example, be configured to have its speed controlled. The motor may include an inverter through which the motor's speed and / or torque output can be regulated.

[0025] The motor can also be controlled by means of an actuator. For example, the actuator may include a sensor configured to detect the position of the actuator. This position can be transmitted to an inverter. The inverter can be configured to control the motor based on the detected position.

[0026] If the actuation element of the throttle valve controller is also configured to control the electric motor, the hybrid drive can be particularly simple and inexpensive. For example, via the rotary handlebars of a small motorcycle, the throttle position can be adjusted proportionally to the rotation position of the handlebars, and a control signal for the electric motor can be generated. Therefore, the electrical control of the electric motor can also be simple.

[0027] Preferably, the parallel hybrid drive includes an energy storage device and a second braking element. The energy storage device is configured to supply electrical energy to and be charged by the motor, and the second braking element is configured to block the drive shaft during the stationary charging operation of the energy storage device. Preferably, the second braking element is a wheel brake. The second braking element can form the drive brake of the motor vehicle. Therefore, the number of braking elements can be small and can be limited to, for example, two or three braking elements. In the case of three braking elements, a third braking element can be configured to brake the non-drive shaft of the motor vehicle, which is configured, for example, the front axle. During driving, the second braking element and the optional third braking element can decelerate the motor vehicle. For this purpose, the second braking element and the optional third braking element can be actuated by the driver of the motor vehicle. The actuation of the second and third braking elements can be coupled to each other, so that only one joint actuation can always be achieved. The operation of the internal combustion engine with the drive shaft braked enables the static charging of the energy storage device. Furthermore, the internal combustion engine can be started from a standstill by the operation of the motor with the drive shaft braked. Therefore, the second braking element can be configured to be continuously adjusted to a closed state by actuation. For example, the second braking element can be configured to be continuously closed in a manner similar to a manual brake.

[0028] Therefore, a hybrid drive can be configured to charge an energy storage device by driving an electric motor with an internal combustion engine. Alternatively or additionally, a hybrid drive can also be configured to charge an energy storage device by using an electric motor to decelerate a motorized vehicle. The energy storage device can be electrically connected to the electric motor via an inverter.

[0029] A hybrid drive may include a charging controller. The charging controller may be formed as part of the electric motor. The charging controller may be formed by or include an inverter. The charging controller may be configured to control the motor based on the charging state of the energy storage device. For example, the charging control system may automatically induce charging of the energy storage device during the driving of the motor vehicle, or reduce the rotational speed and / or power output of the electric motor if the charging state drops below a threshold. The charging controller may be configured to modify the control of the motor based on the position of the actuator according to the charging state of the energy storage device. For example, the charging controller may, specifically by shifting gears, change the characteristic curve of the motor, which determines the motor's rotational speed relative to the position of the actuating element. As a result, the hybrid drive controller is very simple, reliable, and low in complexity. In a low charging state, the total torque of the hybrid drive may be reduced compared to a high charging state. However, the driver can intuitively and easily compensate for this by adjusting the actuation. For example, the driver may further rotate the handlebars of a small motorcycle toward a higher drive output to achieve the desired power output even in a low charging state. The internal combustion engine provides a larger proportion of power compared to a high charging state. For example, there is no need for a complex feedback control system for this purpose; instead, a direct mechanical throttle controller allows the driver to compensate accordingly through his supervision. This also ensures, for example, that sufficient residual charge remains even after driving has ended, so that the internal combustion engine can be restarted via the electric motor. Furthermore, the energy storage device can also be used to power other systems in the motorized vehicle without the risk of them failing due to the energy storage device being completely depleted by the electric motor.

[0030] The hybrid drive may include a charging device configured to charge the energy storage device using an external energy source. For example, the charging device can charge the energy storage device by connecting it to the national power grid.

[0031] The planetary gear can be locked by connecting at least two shafts of the planetary gear using a clutch element. The sun gear shaft, carrier shaft, and ring gear shaft of the locked planetary gear rotate at the same speed. Therefore, the planetary gear no longer rolls on the sun gear shaft and ring gear shaft with its splines, resulting in very high efficiency in the locked state. Preferably, the clutch element is configured to connect a third shaft of the planetary gear to either the first or second shaft of the planetary gear.

[0032] Clutch elements can be configured to switch automatically, for example. Compared to actively switching clutch elements, no actuator is needed to operate the clutch elements. Therefore, hybrid drive systems can be compact and cost-effective. Furthermore, manual actuation of the clutch elements is not required. This simplifies the operation of motorized vehicles.

[0033] The clutch element can be configured to switch based on the rotational speed of the third shaft of the planetary gear. For this purpose, the clutch element can, for example, be connected to the third shaft on one side. During shifting, the connection between the two shafts of the planetary gear unit can be established or disengaged. The rotational speed of the third shaft of the planetary gear can correspond to the rotational speed of the drive shaft, and thus to the driving speed of the vehicle. The clutch element can be configured to connect at least two shafts of the planetary gear to each other when the speed of the third shaft of the planetary gear exceeds a threshold rotational speed. Therefore, the hybrid drive can automatically shift to a locked state from a determined driving speed and thus operate particularly efficiently at high speeds. Furthermore, particularly high performance can be achieved by increasing the driving force in the planetary gear, which allows for particularly high driving speeds. Due to the efficient power transmission in the planetary gear, the hybrid drive can potentially provide more power to the corresponding driven shaft compared to a conventional drive with the same motor.

[0034] Automatic clutch elements can be configured, for example, as centrifugal clutches. Clutch elements can be configured, for example, as friction clutches. Clutch elements can be configured to connect at least two shafts to each other in a rotationally fixed manner by actuation of the clutch element.

[0035] Preferably, both the first braking element and the clutch element are configured to shift automatically. This means that the driver of the motor vehicle does not need to shift gears, making the motor vehicle very easy to operate. For example, the driver only needs to steer, control the power output from both engines, and brake—if necessary—using a common actuation element. For example, no further action is required to control the drive across its entire possible speed range, especially for driving the motor vehicle.

[0036] The motor vehicle according to the invention is constructed as a motorcycle. It includes a parallel hybrid drive according to the invention and a rear wheel driven by the hybrid drive. An example of a motorcycle is a small motorcycle. Due to its compact and cost-effective design, the hybrid drive is also well-suited for other small vehicles, such as snowmobiles, four-wheelers, or children's vehicles. In contrast to power transmission by means of a belt, the hybrid drive can, for example, save up to 25% on fuel and / or provide higher drive power when necessary. The parallel hybrid drive can also be constructed as a pump drive.

[0037] The internal combustion engine can be designed as a two-stroke or four-stroke engine, for example. The electric motor can be configured to convert electrical electricity into mechanical power. The electric motor can be configured as an AC electric motor, for example.

[0038] The method according to the present invention for operating a parallel hybrid drive with a planetary gear in direct drive mode includes the following steps:

[0039] A1: The first shaft of the rotating gear driven by a motor;

[0040] A2: The second shaft that uses an internal combustion engine to drive a rotating gear;

[0041] A3: The motion of the first and second shafts is transmitted to the third shaft of the planetary gear, wherein at least two shafts of the planetary gear are fixedly connected to each other by means of a closed clutch element.

[0042] Because at least two shafts of the planetary gear are securely connected to each other, transfer losses inherent in planetary gears can be avoided. In this mode, the torques of the electric motor and the internal combustion engine are added together. As described above, this mode is particularly suitable for high drive speeds.

[0043] The method according to the present invention for operating a parallel hybrid drive with a planetary gear in all-electric mode includes the following steps:

[0044] B1: The first shaft that uses a motor to drive a rotary gear;

[0045] B2: The first braking element prevents the internal combustion engine connected to the second shaft of the planetary gear from rotating backward;

[0046] B3: Transmits the motion of the first shaft to the third shaft of the planetary gear.

[0047] Therefore, for example, it is possible to drive in the morning without waking local residents. The internal combustion engine can be configured to automatically start when a speed threshold is exceeded. For example, when exceeding the speed limit of a residential street, the internal combustion engine can automatically engage so that it can subsequently provide more power and even higher driving speeds. In the case of automatic clutch element switching, the internal combustion engine automatically starts when the switching speed is exceeded, for example, due to the inertia of a hybrid drive.

[0048] The method according to the present invention for operating a parallel hybrid drive with a planetary gear in CVT mode includes the following steps:

[0049] C1: The first shaft that uses a motor to drive a rotary gear;

[0050] C2: The second shaft that uses an internal combustion engine to drive a rotating gear;

[0051] C3: Transmits the motion of the first and second shafts to the third shaft of the planetary gear, wherein all shafts of the planetary gear are rotatable relative to each other.

[0052] The operating speed of the internal combustion engine can depend on the speed of the electric motor at a given speed in that mode. This makes it possible to control the speed of the internal combustion engine via the electric motor.

[0053] The dependent claims describe further advantageous embodiments of the invention. Attached Figure Description

[0054] The preferred embodiments are explained in more detail with reference to the following figures. They are shown here:

[0055] Figure 1 This is an example of a parallel hybrid drive for a motor vehicle according to the present invention.

[0056] Figure 2 This is an example of a method according to the invention for operating a parallel hybrid drive in direct drive mode.

[0057] Figure 3 Examples of methods for operating a parallel hybrid drive in all-electric mode according to the present invention, and

[0058] Figure 4 This is an example of a method according to the present invention for operating a parallel hybrid drive in CVT mode. Detailed Implementation

[0059] Figure 1 The parallel hybrid drive 1 shown is part of a miniature motorcycle (not shown) and is configured to drive the rear wheel of the miniature motorcycle. For this purpose, the hybrid drive 1 includes an electric motor 2 and an internal combustion engine 3. The electric motor 2 is an electric motor that can also operate as a generator. The internal combustion engine is a four-stroke reciprocating engine 3.

[0060] In addition, the hybrid drive 1 includes a traction battery 12, which is configured to supply electrical energy to and be charged by the electric motor 2.

[0061] An electric motor 2 and an internal combustion engine 3 are connected to each other via a planetary gear 5. The planetary gear 5 includes a first shaft 6 configured as a ring gear shaft, a second shaft 7 configured as a sun gear shaft, and a third shaft 8 configured as a carrier shaft. In this exemplary embodiment, the first shaft 6 is connected to the electric motor 2, and the second shaft 7 is connected to the internal combustion engine 3. The third shaft 8 of the planetary gear 5 is connected to the drive shaft 4 of a miniature motorcycle via a chain 11. In other embodiments, the third shaft 8 may also be directly or via a spur drive to the drive shaft 4.

[0062] Furthermore, the hybrid drive 1 includes a clutch element 9. In this exemplary embodiment, the clutch element is configured as a centrifugal clutch 9, which engages when the speed of the mini-motor is below 30 km / h. When the centrifugal clutch 9 is engaged, the rotational speed of the internal combustion engine 3 can be controlled by the electric motor 2 via a connection between the two electric motors 2 and 3 through a rotary gear 5. Therefore, the rotational speed of the internal combustion engine 3 can be continuously varied within the low speed range of the mini-motor.

[0063] Furthermore, the hybrid drive 1 includes a throttle valve controller (not shown) configured to set the torque of the internal combustion engine 3 at a speed specified by the electric motor 2. The throttle valve controller used in the exemplary embodiment enables purely mechanical load control of the internal combustion engine 3 without electronic components.

[0064] When the speed of the small motorcycle exceeds 30 km / h, the centrifugal clutch 9 engages and securely connects the first shaft 6 and the third shaft 8. When the centrifugal clutch 9 is engaged, all shafts of the planetary gear 5—shafts 6, 7, and 8—rotate at the same speed. This allows the internal combustion engine 3 to be supported by the electric motor 2. The fixed connection between the shafts enables direct drive without conversion losses in the planetary gears.

[0065] Furthermore, the hybrid drive 1 includes a first braking element 10. In an exemplary embodiment, the first braking element is a roller freewheel 10 arranged between the internal combustion engine 3 and the second shaft 7. The freewheel 10 is configured to prevent rearward rotation of the internal combustion engine 3. As a result, the torque used to drive the scooter can be controlled by the electric motor 2 and can be transmitted to the drive shaft 4 independently of the internal combustion engine 3 when the centrifugal clutch 9 is engaged. This enables the scooter to operate purely electric.

[0066] Furthermore, the hybrid drive 1 includes a second braking element 13 configured to brake the drive shaft 4. In this exemplary embodiment, the second braking element is a wheel brake 13. By operating the internal combustion engine 3 and simultaneously blocking the drive shaft 4 via the wheel brake 13, mechanical energy is transmitted from the internal combustion engine 3 to the electric motor 2 via the planetary gear 5. The electric motor 2 converts mechanical energy into electrical energy during the operation of the working machinery. This allows the traction battery 12 to be charged independently of an external power source while stationary. Furthermore, this arrangement enables the internal combustion engine 3 to be started from a standstill by means of the electric motor 2. The starting torque required to start the internal combustion engine 3 from a standstill is provided by the electric motor 2 and is also provided at the wheel brake 13.

[0067] The different operating modes of a parallel hybrid drive are explained below.

[0068] Figure 2An embodiment of a method according to the invention for operating a parallel hybrid drive 1 in direct drive mode is shown. In this mode, the centrifugal clutch 9 is closed. All shafts of the planetary gear set are fixed to each other. In the first step of method A1, the first shaft 6 of the planetary gear set 5 is driven by an electric motor 2. In the second step A2, the second shaft 7 of the planetary gear set 5 is driven by an internal combustion engine 3. In the third step A3, the motion of the first shaft 6 and the second shaft 7 is transmitted to the third shaft 8 of the planetary gear set 5. This causes the torques of the electric motors 2 and 3 to be added together, resulting in high wheel torque. Since all the wheels of the planetary gear set 5 are securely connected to each other via the closed centrifugal clutch 9, no significant conversion losses occur in the planetary gear set 5. Compared to conventional drives with gears exhibiting frictional losses, the parallel hybrid drive 1 in direct drive mode exhibits higher overall efficiency. Therefore, fuel savings can be achieved during vehicle operation. Steps A1 to A3 are performed simultaneously in the described method.

[0069] Furthermore, the parallel hybrid drive 1 can operate in all-electric mode using the method according to the invention. Figure 3 An embodiment of the method is shown. In this mode, the centrifugal clutch 9 is open. In the first step of method B1, the first shaft 6 of the planetary gear 5 is driven by the electric motor 2. In the second step B2, the rearward rotation of the internal combustion engine 3 is prevented by the freewheel 10. In the third step of method B3, the motion of the first shaft 6 is transmitted to the third shaft 8 of the planetary gear 5. In the exemplary embodiment, this results in the purely electric drive of the rear wheel of the miniature motorcycle. Steps B1 to B3 are performed simultaneously in the described method.

[0070] Furthermore, the parallel hybrid drive 1 can be operated in CVT mode using the method according to the present invention. Figure 4 An exemplary embodiment of the method is shown. In this mode, the centrifugal clutch 9 is open. All the gears of the planetary gear 5 can rotate relative to each other. In the first step of method C1, the first shaft 6 of the planetary gear 5 is driven by the electric motor 2. In the second step C2, the second shaft 7 of the planetary gear 5 is driven by the internal combustion engine 3. In the third step C3, the motion of the first shaft 6 and the second shaft 7 is transmitted to the third shaft 8 of the planetary gear 5. Steps C1 to C3 are performed simultaneously in the described method. In this method, the speed of the internal combustion engine 3 can be adjusted by controlling the speed of the electric motor 2. This enables continuously variable transmission (CVT), in which the power obtained from or supplied to the battery 12 can be adapted to its state of charge. Starting elements, such as friction clutches or converters, can be omitted. This reduces losses during the starting process compared to conventional drives with starting elements.

Claims

1. A motor vehicle having a parallel hybrid drive (1), wherein the hybrid drive (1) comprises a) An electric motor capable of operating as both a motor and a generator (2), b) Internal combustion engine (3), c) Drive shaft (4), d) A rotating gear (5), which includes - First shaft (6), which is connected to the motor (2), - A second shaft (7), which is connected to the internal combustion engine (3), and - A third shaft (8), which is connected to the drive shaft (4), e) A clutch element (9) configured to securely connect at least two shafts of the planetary gear (5) to each other, and f) A first braking element (10), which is designed to prevent the internal combustion engine (3) from rotating rearward. The clutch element (9) is configured as a centrifugal clutch, and the clutch element (9) is configured to automatically switch based on the rotational speed of the third shaft (8) of the planetary gear. The motor vehicle includes a throttle valve controller with direct mechanical control, the throttle valve controller being configured to regulate the torque of the internal combustion engine (3) at a speed specified by the motor (2); The motor vehicle includes an actuation element that is directly mechanically connected to a throttle valve via a Bowden cable and is configured to control a motor (2). For this purpose, the actuation element includes a sensor configured to detect the position of the actuation element, which is transmitted to an inverter for controlling the motor (2).

2. The motorized vehicle according to claim 1, wherein, The first braking element (10) is configured to switch automatically.

3. The motor vehicle according to any one of the preceding claims, wherein, The first shaft (6) is a ring gear shaft, the second shaft (7) is a sun gear shaft, and the third shaft (8) is a carrier shaft.

4. The motor vehicle according to any one of claims 1-2, wherein, The motor (2) is configured to control the rotational speed of the internal combustion engine (3) when the clutch element (9) is open.

5. A motor vehicle according to any one of claims 1-2, comprising an energy storage device (12) and a second braking element (13), the energy storage device (12) being configured to supply electrical energy to and be charged by the motor (2), and the second braking element (13) being configured to prevent the drive shaft (4) during a stationary charging operation of the energy storage device (12).

6. The motorized vehicle according to claim 5, wherein, The motor (2) is configured to start the internal combustion engine (3) from a standstill when the drive shaft (4) is stopped.

7. The motor vehicle according to any one of claims 1-2 and 6, wherein the motor vehicle is configured as a small motorcycle.

8. The motor vehicle according to claim 7, wherein, The actuating element is configured as a rotating handlebar on the handlebars of the miniature motorcycle.

9. The motor vehicle according to claim 7, the motor vehicle comprising rear wheels capable of being driven by the parallel hybrid drive (1).

10. The motor vehicle according to claim 2, wherein the first braking element (10) is configured as a freewheel.

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