JP2011057194A - Transmission with motor for hybrid automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an inexpensive and light full hybrid vehicle (HEV) by combining a manual transmission (MT) with a motor having a minimum output. <P>SOLUTION: An input shaft of a transmission of the MT may be driven by sufficiently reducing speed of rotation of a generator used also as a motor for traveling having a small output (Motor Generator) to obtain torque for starting an automobile by the MG. But, the number of rotation of the MG co-rotated when an engine is highly rotated becomes too high rotation and the motor is destroyed by centrifugal force in the case. By using a two-stage transmission mechanism having a first speed reduction ratio taking charge of starting and initial acceleration and a second speed reduction ratio taking charge of energy recovery during speed reduction, the light and inexpensive full HEV is realized by connecting the MG to an input shaft of the transmission. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

Technical background

For the purpose of improving the fuel efficiency of automobiles, hybrid automobiles (hereinafter referred to as HEVs) in which a motor using an internal combustion engine as a power source is combined with a driving motor and a battery are manufactured.
There are two types of HEV known as series hybrid and parallel hybrid.
In order to improve HEV's low-speed fuel consumption, it is necessary to start and accelerate with only the driving force of the motor with the engine disconnected from the axle. For this purpose, a large and heavy motor with an output comparable to the engine is required. Because of the need to supply a large amount of power, heavy and expensive large capacity secondary batteries, generators, inverters, etc. are required, which inevitably makes full HEV cars heavy and expensive.
In addition, since a full-heavy full HEV drive system is significantly different from a normal engine vehicle, it is necessary to use a dedicated drive system, which further increases the manufacturing cost.

A hybrid vehicle using an engine and / or motor as a vehicle propulsion source is known (see, for example, Japanese Patent Laid-Open No. 5-50865). In this type of hybrid vehicle, at the time of normal start, the clutch is released and started by the driving force of the motor, and when the vehicle speed increases, the engine is started and the clutch is engaged, and the vehicle is driven by the driving force of the engine.

An object of the present invention is to establish a full-hybrid vehicle (full HEV) having a large fuel efficiency improvement rate that can be started and accelerated by only a small output traveling motor at a low weight and at a low cost.
Currently, the only full HEV that can be started with only a motor is a THS system of Toyota Motor Corporation, but for the reasons described above, it has a rather complicated structure compared to the same class car, so it is an expensive and heavy car. Yes.
Furthermore, since the THS system is basically a series HEV, there is an energy loss due to energy conversion from the generator to the motor, and there is a disadvantage that high-speed fuel consumption is inferior to MT.
Honda's IMA is less expensive than THS because it has less than half the capacity of the motor and battery, but it cannot be started with the motor alone, and has the drawback of reducing fuel consumption.

Means to solve the problem

In order to obtain sufficient torque for starting and initial acceleration with a small output motor, the objective is achieved by increasing the reduction ratio and converting the motor speed to torque.
In the case of a HEV that combines a car with an engine output of 30 Kw and a motor of 6 Kw with a output of 1/5, a full HEV that can start with only the power of the motor has not been established until now.
However, if the engine can produce a speed of 150 Km / H, the output required to produce a speed of 30 Km / H can be made in 2Kw of 1/25 considering the kinetic energy and running resistance of the vehicle. Become.
In addition, an electric vehicle capable of traveling 100 km with a single charge needs to be loaded with a very large amount of battery, but if the travel distance is 2 km, the battery capacity may be 1/50.
In other words, if an ordinary MT car is combined with a small output motor capable of accelerating from the start to 30 km / h and a small capacity battery capable of traveling by 1000 m, full HV can be realized at a very low cost.
FIG. 1 shows a torque curve of a general engine, a torque curve of an ideal performance motor having 1/6 output of the engine, and a combined torque curve of both. An ideal motor has a hyperbolic characteristic in which the torque doubles when the rotational speed is halved.
As shown in this combined torque curve, a sufficient starting torque can be generated even with a motor having only 1/5 the output of the engine.
However, there is actually no motor with such ideal performance.
FIG. 2 shows a torque curve of a general engine, a torque curve of a general performance motor having 1/5 engine output, and a combined torque curve of both.
As shown in this composite torque curve, it can be seen that a normal motor having only 1/5 of the output of the engine cannot be started by the motor and is not very useful.
FIG. 3 is a torque curve diagram of the engine and a motor having a general performance decelerated to 1/6 and a combined torque curve of both.
When a motor having a constant output characteristic is decelerated, the rotational speed becomes 1 / N and the torque becomes N times, but the torque characteristic is on the same hyperbola.
As shown in this combined torque curve, a sufficient starting torque can be generated by decelerating even a general motor having only 1/5 output of the engine.
However, if the engine rotates at a high speed, the motor will over-rotate and cannot be rotated.
Therefore, when the rotational speed of the input shaft of the transmission rises to some extent, switching to the second reduction ratio as shown in FIG. 4 makes it possible to perform weak torque assist and recovery of deceleration energy in the entire engine speed range. It will be possible.
In other words, by combining an actual motor and a two-stage transmission, an operation similar to that of a motor having ideal characteristics can be achieved.

The invention's effect

A permanent magnet reluctance motor having a constant torque characteristic with a rated output of 6 Kw and 3000 rpm or less and having a wide constant output characteristic in which the rotation speed and torque are in inverse proportion to the maximum rotation speed of 15000 rpm will be described as an example.
As shown in FIG. 1, if a 30 Kw engine produces a maximum output at 6000 rpm, this motor will produce 20% of the engine's torque at the same speed. The rotational speed and torque are inversely proportional to the characteristics of the motor, but at 3000 rpm or less, it has a constant torque characteristic and becomes 40% torque, and even if the rotational speed decreases from there, the torque does not increase any further. As shown in FIG. 2, if used as it is, it will not be very useful as a running motor (hereinafter referred to as a motor).
Therefore, as shown in FIG. 3, if the rotational force obtained by reducing the rotation of the motor to 1/6 is added to the input shaft of the transmission, the input shaft of the transmission is 500% or less at 240% of the maximum engine torque and 800 rpm. The torque is 150%, 100% at 1200 rpm, and 60% at 2000 rpm. This makes it possible to start the vehicle and start acceleration with only the motor. The rotation of the motor is 16000 rpm (the rotation speed after deceleration is 2600 rpm), and the rotation speed is limited.
The torque curve is when the motor is driven at the maximum output, and in an actual start-up operation in the city, it operates with a margin even with considerably less power. In other words, the traveling battery is small and will be in time.
When a larger torque is required such as sudden start, control is performed so that the total torque of both the engine and the motor is applied to the transmission.
However, if the rotation of the motor is reduced to 1/6 and fixedly coupled to the input shaft of the transmission, the motor will be rotated at 48000 rpm when the engine is rotated up to 8000 rpm, and the motor rotor Will be destroyed by centrifugal force. To prevent this, a clutch is attached to the speed reduction mechanism as shown in FIG. 5, and the motor is disconnected when the engine speed reaches a certain level.
HEV generally employs a motor generator (MG) that operates a motor as a generator during deceleration. For this reason, it is impossible to recover kinetic energy during deceleration by simply separating the MG.
Therefore, by providing a second reduction mechanism that connects the motor and the input shaft of the transmission and a clutch at a reduction ratio (in this example, about 1/2 reduction ratio) that can rotate around MG even at the maximum engine speed, full HEV It is possible to start with only the essential motor and recover the kinetic energy during deceleration with a small output MG and a small capacity secondary battery.
That is, the present invention eliminates the need for a high output motor, a high output generator, a large capacity secondary battery, and a specific drive system that are essential for a full HEV, so that the full HEV can be realized at a very low cost.
Further, the second speed reduction mechanism makes it possible to perform weak motor assist when the traveling load is small in the entire rotation range of the engine.
As shown in FIG. 1, the present invention is useless if there is a motor having an ideal constant output characteristic. However, since such a motor does not actually exist, an actual motor is idealized by combining the two-speed shift of the present invention. It approximates this characteristic.
In the present invention, starting and initial acceleration are performed only by the output of the motor, but when the amount of charge of the running battery is insufficient or when a larger acceleration is required, the engine is rotated and the output of the alternator is used for driving the motor.
In the structure of the present invention, since the required driving motor output is small, the electric power required is similarly small. The alternator can be diverted to the generator for driving the traveling motor by stopping the operation of limiting the generated voltage of the normal alternator to 14 V and increasing the generated voltage. This eliminates the need for a travel-only generator, thereby reducing costs and weight.
Some Toyota Motor's THSII has a structure that uses a planetary gear to perform a two-speed shift. In this case, when the two-speed transmission is set to a neutral state that does not transmit power, both the engine and the motor drive the wheels. Cannot be transmitted. In the present invention, even if the motor is disconnected, the rotational force of the engine is transmitted to the axle, or conversely, the rotational force can be transmitted to the wheels to the input wheel, so that the operation is different. In other words, the THSII two-stage shift operates in the same manner (role) as the MT of the present invention.
By using the structure of the present invention, starting and initial acceleration use only a motor so that the engine can be used in a state of poor fuel consumption, and when the initial acceleration is completed, transmission efficiency using gears as in normal MT is completed. Since the engine runs with a good transmission, fuel efficiency is good over the entire speed range. Since it is not necessary to use a slip clutch for starting, there is no problem with wear and operation feeling at extremely low speeds, and there is no decrease in transmission efficiency due to the use of a torque converter.
Since the transmission of the present invention is a single-clutch MT, when the maximum starting acceleration is required, the transmission is sequentially shifted up from the first speed. However, in general start acceleration in the city, so much acceleration is not necessary, so it is possible to start at the third speed by utilizing the very large torque of the motor after deceleration applied to the transmission input shaft. is there.
The HEV that connects the MG to the transmission using only a clutch has existed so far, but by combining the two-speed transmission mechanism, an HEV with a significantly reduced capacity of the MG, battery, and inverter is established.

Best Mode for Carrying Out the Invention

The structure is such that the rotational force of the motor (MG) is transmitted to the input shaft of the transmission through the clutch, and the rotational force of one of the gears is transmitted using two gears. When the battery is sufficiently charged when the engine is in a running state, energy loss caused by separating both gears and rotating the MG can be eliminated.

FIG. 5 shows a structure in which the rotational force of MG is transmitted to the input shaft of the FF transmission by two systems of gears and a clutch (such as a dog clutch).
The reverse gear can be eliminated by rotating the motor in the reverse direction, as is often done in EV.
The HEV control unit uses the engine and motor driving force, engine clutch, and motor clutch individually to obtain the torque required for the driver's desired acceleration indicated by the amount of depression of the accelerator pedal at the current speed. To control.
When starting, the engine clutch is disengaged and the engine torque is not transmitted to the transmission, and the motor starts only. The gear shift of the speed machine may be manual or automated.

Industrial applicability

Currently, sales of HVE are very strong, but production of HVE is limited to some manufacturers. The reason for this is that the structure of the drive system of the HVE is considerably different from that of a normal automobile powered by only an engine, and it is very expensive to develop and produce, so it is difficult to manufacture HEV. In the present invention, a full HEV can be established on the basis of a normal MT vehicle, and there is a possibility that it can be produced at a lower cost and lighter than general ATs and CVTs as well as conventional HEVs.
Also, the resources required for manufacturing can be greatly reduced compared to a normal HEV, and a truly environmentally friendly HEV vehicle can be realized.

These are a general engine torque curve, a torque curve diagram of an ideal performance motor having 1/5 engine output, and a combined torque curve of both. These are a general engine torque curve, a torque curve diagram of a general performance motor having 1/5 output of the engine, and a combined torque curve of both. These are a torque curve diagram of a motor having a general performance decelerated to 1/6 and a combined torque curve of both. These are a torque curve diagram of an engine and a motor having a general performance decelerated to 1/2, and a combined torque curve of both. Is an application of the present invention to an ordinary FF synchromesh transmission. Is an overall system diagram.

Claims (1)

An invention related to realizing a hybrid vehicle at low cost by adding a motor / generator for traveling to a transmission in a vehicle having a drive system of a normal single clutch synchromesh transmission.
In the above drive system, the input shaft of the transmission is connected to the rotating shaft of a motor generator (hereinafter referred to as MG) having a wide constant output characteristic such as a permanent magnet reluctance type through a reduction mechanism capable of shifting in two stages. A transmission for a hybrid vehicle.
The first speed change ratio (speed change ratio for starting and initial acceleration) is a speed change in which the speed of the input shaft of the transmission is about 20 to 40% of the maximum speed of the engine when the MG is driven at the maximum speed. Is the ratio. The second speed change ratio is a speed change ratio having a value for transmitting a rotation that allows the MG to generate sufficient regenerative electric power at the time of deceleration without causing the MG to be excessive at the maximum engine speed.

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