MXPA96005867A - Vehiculo de tren de potencia hibrido - Google Patents

Abstract

Engine (1) output speed is controlled for optimum efficiency by adjustment of input speed of a continuously variable transmission (CVT) (3). Where power in excess of that provided by the engine (1) is required, additional power is input to the drive train from a fluidic motor (7) driven by fluid pressure stored in an accumulator (6). In driving conditions where the engine (1), operating at optimum efficiency, produces power in excess of that demanded by the vehicle, the fluidic motor (7) is reversed for operation as a pump and excess engine power is utilized to drive the pump (7) and store energy in the accumulator (6) in the form of fluid pressure. A CPU (18) determines power output required of the engine (1) as a sum of that indicated by a sensor (14) which senses power demanded of the vehicle by a driver and an increment of power required to maintain the pressure of the accumulator (6) above a threshold amount.

Description

VEHICLE DB HYBRID POWER TRAIN - Background of the Invention 1. Field of the Invention The invention relates to an automotive hybrid power train design that allows a highly efficient use of the energy generated by an internal or external combustion engine. The field of application is in propulsion systems for motor vehicles. 2. Previous Art The increased use of automobiles greatly adds to the atmospheric presence of various pollutants including greenhouse gases such as carbon dioxide. For this reason, there has been a purpose to improve fuel efficiency for automotive power trains. Current power trains typically average only about 10 to 15% of thermal efficiency. * Conventional automotive power trains result in significant energy loss, make it difficult to effectively control emissions and offer limited potential to bring major improvements in the automotive fuel economy. Conventional power trains consist of an internal combustion engine and a simple mechanical transmission having a discrete number of gear ratio. Due to the inefficiencies described below, about 85% to 90% of the fuel energy consumed by such a system is wasted as heat. Only 10% -15% of the energy is available to power the vehicle, and much of this dissipates as heat in braking.

Much of the energy lost is due to a poor match between the power capacity of the engine and the average power demand. The load placed on the motor at any given moment is determined directly by the total path load at that instant, which varies between extremely high and extremely low load. To fill the acceleration recessions, the motor must be much more powerful than the average power required to drive the vehicle. The efficiency of an internal combustion engine varies significantly with the load, being better at higher loads near the peak load and at worst at a low load. Since the operation of the engine experienced in normal operation is almost always at the low end of the spectrum, the engine must operate at a poor efficiency much of the time, even if some conventional engines have peak efficiencies in the range of 35% to 40% .

Another major source of energy loss is braking. In contrast to the acceleration that requires the delivery of energy to the wheels, braking requires the removal of energy from the wheels. Since the internal combustion engine can only produce and not reclaim energy, a conventional powertrain is a one-way energy path. The braking is achieved by a friction braking system, which makes the kinetic energy temporarily unnecessary of the vehicle useless by converting it into heat.

The wide variation in speed and load experienced by the engine in a conventional powertrain also makes it difficult to effectively control emissions because it requires the engine to operate at many different combustion conditions. Operating the motor at a more constant speed and a load would allow a better optimization of any emission control devices, and in general more efficient engine settlements would allow less fuel to be burned per kilometer traveled.

Conventional power trains offer limited potential to provide improvements to the fuel economy of automobiles except when combined with improvements in aerodynamic drag, weight and rolling resistance. Such refinements can only offer incremental efficiency improvements, and can equally well be applied with improved power trains.

Hybrid vehicle systems have been investigated as means to mitigate previous inefficiencies. A hybrid vehicle system provides a "shock absorber" between the power required to drive the vehicle and the power produced by the internal combustion engine in order to moderate the variation in power demand experienced by the engine. The shock absorber also allows regenerative braking because it can receive and store energy from sources other than the engine. The effectiveness of a hybrid vehicle system depends on its ability to operate the engine at peak efficiencies and on the efficiency of the buffering medium. Buffer means include electric batteries, mechanical wheels and hydraulic accumulators.

To use a hydraulic accumulator as the shock absorber, a hydraulic motor / pump is integrated into the system. The pump / motor act interchangeably as a pump or motor. Like a pump, the pump / motor uses the power of the motor or "braking" to pump electrical fluid to an accumulator where it is pressurized against a volume of gas (eg nitrogen). As an engine, the pressurized fluid is released through the pump / motor, producing power.

There are two general classes of hydraulic hybrid vehicle systems. A "series" system directs all the energy produced by the motor through a fluid power path and thus is the side of the fluid power that experiences the variable path load. This improves the efficiency because the efficiency of the fluid power path is not sensitive to variations in power demand, and because the motor is therefore decoupled from the load of the road, allowing the latter to operate at a Efficiency peak or be off. Series systems are relatively simple in concept and control, but have less potential for efficiency than other systems because all energy must be converted to fluid power and back to mechanical power to drive the vehicle. These also depend on the frequent on / off operation of the motor for optimum efficiency. "Parallel" systems divide the power flow between an almost conventional direct mechanical drive line and a fluid power path. Therefore, some of the energy is released from the conversion to fluid power and back again. The most common context for such systems is in a "throw help" mode where the hydraulic system serves primarily to store braking energy and to deliver it again to assist in the next vehicle acceleration. The parallel system, because it requires both the hydraulic and conventional power path to the wheels, tends to be more complex than the series system and more difficult to control for smoothness. Depending on the specific design, both series and parallel systems allow some reduction in the size of the motor but still tend to require a relatively large motor.

For example, the United States patent of North America No. 4,223,532 (September 23, 1980) issued to Shiber describes a hydraulic hybrid transmission system which uses two pumps / motors and is based on a theory of "which encourages intermittent engine operation.

Synthesis of the Invention Therefore, it is an object of the present invention to provide a hybrid power train system which allows a significant reduction in the size of the internal combustion engine for the vehicle.

It is a further object of the present invention to provide a power train system which allows the internal combustion engine of the vehicle to be operated constantly at an almost peak efficiency.

It is yet another object of the present invention to provide a hybrid propulsion system wherein the currently unnecessary power generated by the internal combustion engine can be stored in a "shock absorber" to be used to produce the driving force (1) in such moments when the internal combustion engine alone is sufficient to provide the torsional output power demanded from the vehicle and (2) at times of a very low power demand when engine operation would be inefficient, for example, in a traffic jam .

Still another object of the present invention is to provide a power train design "that allows a more highly efficient use of the energy generated by the internal combustion engine than has been possible heretofore.

Still another object of the present invention is to provide a hybrid powertrain propulsion system which allows extreme variations in the road load while maintaining high efficiency.

The present invention provides a unique "parallel" hybrid propulsion system and a method of operation which fulfills the stated objectives. Specifically, the hybrid power train vehicle of the present invention includes a vehicle frame supported on a road surface by the drive wheels rotatably mounted thereon. A primary motor, for example an internal or external combustion engine, mounted on the vehicle frame provides the output motor power and output shaft in a conventional manner. A power storage device is also mounted on the vehicle frame to serve as a "shock absorber", for example to store and release the "excess" and braking power of the engine. A first drive train serves to transmit the motor power to the drive wheels and includes a continuously variable transmission (CVT) having a moving pulley of a variable effective diameter (or other multiple gear ratio transmission).

In the preferred embodiment, reversible fluidic displacement means or "reversible pump / motor" are interposed between a fluid pressure accumulator and the first drive train to draw motor power to the first drive train, driven by the pressure of accumulator fluid in a first mode and to operate as a pump, driven by the first drive train, to store fluid pressure in the accumulator in a second mode. In other embodiments, the power storage device may, for example, be the combination of a storage battery, generator / alternator and an electric motor.

A second drive train serves to connect the power storage device to the first power train thereby defining a "parallel" propulsion system.

The control of the propulsion system is provided, in part, by three sensors such as for example a vehicle speed sensor, a power storage sensor, for example a pressure sensor for sensing the fluid pressure inside the accumulator and a sensor of demand of torsional force (or energy) to perceive the demand for torsional force (or power) of the vehicle by the handler, for example a sensor for the position of the "throttle valve" pedal or the depression of the "accelerator" pedal . A microprocessor includes comparing means for comparing the perceived value of the stored power with a predetermined minimum value for the stored power and for generating a demand signal with a determination of "that the perceived value for the stored power is at or below a minimum value. predetermined. The microprocessor also includes a means of determining torsional force output to determine an additional torsional force according to the demand signal and to determine a motor output torsional force as the sum of the demand for perceived torsional force and the torsional force additional. The microprocessor also includes a motor speed determination processor to determine an optimum efficiency motor speed according to the determined motor output torsional force and the perceived vehicle speed and to output a transmission signal, indicative of the Motor speed determined. Motor speed control means control the rotational speed of the output shaft of the motor by changing the gear ratio of the transmission. In the preferred embodiment this involves changing the effective diameter of the CVT mobile pulley, "which responds to the output of the transmission signal by the engine speed determination processor. A motor load controller controls the power of the motor by controlling the supply of fluid to the primary combustion engine that responds to the transmission signal. A mode controller serves to switch the power storage device between power storage and power release modes. In a preferred embodiment, the mode controller serves both for the operation of converting the fluid displacement means between the first and second modes of operation, in response to the demand signal and to vary the displacement of the fluid displacement means. in response to the perceived fluid pressure.

Optionally, a secondary motor, for example internal combustion is mounted on the vehicle frame to provide an additional motor capacity that might be necessary, for example, to climb a particularly steep slope. When the secondary motor is mounted on the vehicle, a secondary motor clutch is interposed between the output of the secondary motor and the first drive train to equalize the output speed of the secondary motor with the output of the primary motor.

The propulsion system of the present invention optionally further includes a freewheel clutch interposed between the transmission (CVT) and the drive wheels to disengage the drive wheels of the first drive train in response to a signal indicating a zero power demand. .

In the present invention, the propulsion system is controlled by perceiving the vehicle speed, perceiving the fluid pressure inside a fluid pressure accumulator and perceiving the power demand of the vehicle by the handler. A reversible fluidic displacement vehicle (pump / motor) is switched between a pump mode and an engine mode in response to a demand for torsional force and available fluid pressure stored in the accumulator. The perceived fluid pressure is compared to a predetermined minimum fluid pressure and, if determined to be below the predetermined fluid pressure, a demand signal is generated. The additional torsional force necessary to adequately raise the fluid pressure was determined according to the demand signal and a motor output torsional force was determined as the sum of the perceived torsional force demand and the determined additional torsional force. An engine speed controller controls the rotational speed of the output shaft by changing the effective diameter of a mobile pulley of the «CVT in response to a transmission signal. A motor speed processor, in turn, determines an optimum efficiency motor speed according to the determined motor output torsional force and the perceived vehicle speed and the outputs of a transmission signal indicative of the determined motor speeds. . The output power of the internal combustion engine is controlled by controlling the fuel supply thereto in response to the transmission signal.

In contrast to previous art, the present system re < wants only one pump / motor in the primary power train and uses the hydraulic subsystem in such a way as to use a very small motor and keeps the engine running as much as possible.

The invention is a single type of a "parallel" system, but it can operate in a series configuration as well. The system of the present invention includes a very small motor sized near the average power requirement rather than the peak power requirement. The hydraulic subsystem acts as a power trim device to "trim" the power demand experienced by the engine. That is, the main purpose of the hydraulic subsister.a is to keep the operation of the engine as close as possible to its peak efficiency by placing additional load on the engine at the time of a low power demand and deliver additional power at times of peak or high propulsion power demand. In the present invention, a single hydraulic pump / motor and an accumulator achieve both functions. To place an additional load on the motor, the motor is run at a power level corresponding to a peak efficiency and the excess power is directed through the pump / hydraulic motor (operating as a pump) inside the accumulator where it is stored with very little loss of energy. To deliver the additional power, the stored energy is discharged to the power train through the pump / hydraulic motor (operating as a motor).

In its simplest configuration, a clutch arrangement between the transmission and the wheels allows free rolling when power train power is not required. However, for simplicity, no clutch is provided between the motor, the pump / hydraulic motor and the transmission. Therefore, the motor can occasionally be monitored while the pump / motor is charging the accumulator during regenerative braking or when small amounts of power are delivered by itself. This creates a load on the train * of power that reduces efficiency somewhat. The friction losses associated with this arrangement are eliminated due to the small displacement of the internal combustion engine and the small amount of time in this mode of operation.

The present invention includes at least two hydraulic regenerative braking configurations. In the first mode, the friction brakes are activated first, after which the hydraulic braking is phased. This method reduces the sophistication of the controls that would be required to effect a smooth steering of power from the wheels, and allows a safety in the event of a failure of a hydraulic system. In the second mode, hydraulic braking occurs first with the friction brakes added as a backup system. This second mode is somewhat more complex to control, but it is the preferred mode because it maximizes braking energy recovery.

When accelerating from a stop, the motor provides power to the wheels through the non-hydraulic part of the drive pipe. If more power is required than the motor can provide, the additional power is supplied by the pump / motor acting as a motor. The accumulator is of sufficient size to allow this additional power to be provided two or more times in succession. The accumulator capacity for at least one acceleration is necessary for regenerative braking and the capacity for another is necessary as a backup in the event that a stop does not allow regenerative braking.

When traveling at a cruising speed and this is reached and the demand power drops to a low level, the motor output equals the road load because the motor is sufficiently small so that its peak efficiency corresponds to the loads characteristics of the average road load. If more motor power is required in order to maintain peak operating efficiency, an additional load is provided by charging the accumulator through the pump / motor acting as a pump. If the accumulator can not accept more load, the pump / motor is set to a zero offset and the motor merely runs at a reduced power output. Given "that the engine is designed near the average power load during circulation, there is little or no sacrifice of efficiency in this way. The motor can also be turned off and the accumulator can boost the pump / motor acting as a motor, if the load is very low as it would happen in low speed, stop and walk traffic.

When braking occurs, if there is enough unused storage capacity reserved in the accumulator, regenerative braking occurs where the pump / motor acts as a pump to charge the accumulator. If there is no remaining capacity in the accumulator, the friction brakes are used. The system is managed so that there will normally be enough available capacity for regenerative braking.

If a sudden acceleration is required during a period of circulation, this can be provided by driving the engine output along the best efficiency line. After the maximum efficient motor power output point has been reached, the hydraulic subsystem is activated to recover the additional power from the accumulator through the pump / motor.

When the engine moves at a very low speed, such as in a traffic jam, the engine shuts down and the pump / motor and accumulator are used to drive the car. This is better than using the engine alone in such a mode because the pump / motor can operate at a good efficiency even at low speeds and at low power demands.

Through an adequate choice of component sizes and optimization of the control system, the system can be designed to optimize several objectives. For example, one can minimize the opportunity of any: a) find a fully charged accumulator when regenerative braking energy becomes available, or b) exhaust the accumulator by several rapid accelerations with no opportunity to recharge the accumulator.

The use of the small motor complemented by an accumulator of finite energy storage capacity presents a difficulty when ascending long slopes. As with acceleration, the ascent of a hill requires an unusually large amount of power, but unlike acceleration a very large hill requires this power for an extended period of time. Since the theory of operation of the invention is to provide a large part of the acceleration power by means of a hydraulic accumulator, a long slope will exhaust the accumulator in a short time and the vehicle would be left with insufficient power.

As an alternative for an extremely large accumulator capacity, a second motor, which can be cheap and of moderate durability due to its occasional use, can be clutched to supplement the power of the primary motor and / or pump / motor for an unlimited time .

Brief Description of the Drawings Figure 1 is a schematic diagram of a first embodiment of a vehicle equipped with a hybrid powertrain propulsion system of the present invention.

Figures 2a, 2b, 2c and 2d are graphs of engine load versus engine speed in various modes of operation of the system shown in Figure 1.

Figure 3 is a schematic illustration of a vehicle equipped with a second embodiment of a hybrid powertrain propulsion system according to the present invention.

Figure 4 is a schematic illustration of a vehicle equipped with a third embodiment of a hybrid powertrain propulsion system according to the present invention.

Figure 5 is a schematic illustration of a vehicle equipped with a fourth embodiment of a hybrid power train propulsion system according to the present invention.

Fig. 6 is a logical flow diagram for contrasting operation of a vehicle by a microprocessor according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Figure 1 illustrates one embodiment of the present invention suitable for driving a vehicle of three to four thousand pounds. A very small internal combustion engine 1 (for example 20 hp) provides power to the system. The energy is transmitted along a drive axis 2 which constitutes a first power train, and can be directed either to the transmission 3, in this mode a continuously variable transmission (CVT) or to the pump / motor 7 ( acting like a pump in the second mode) or both. The pump / motor 7 is a reversible hydraulic displacement device, for example a drive plate pump in which the flow reversal is inherent to the pump or a bent shaft pump where the flow reversal is by external valves to the pump. pump, capable of operating either in a first mode as a motor or in a second mode as a pump. The pump / motor 7 has a variable displacement. The energy directed to the pump / motor 7 (acting as a pump) is used to pump fluid to the accumulator 6, pressurizing the fluid B against a volume of gas A. The energy directed to the transmission flows along the lower drive shaft 9 beyond the wheel clutch free 4 to the wheels 5. The motor / buffer 7 is switched between its first and second modes and its displacement is varied by a pump / motor controller 20, in response to a signal FPs.

When the power demanded on wheels 5 is greater than the power that can be delivered by engine 1 only, the additional power is provided by the pump / motor 7 (acting as a motor in the first mode). In this mode the pressurized fluid in the accumulator 6 flows to the pump / motor 7 (acting as a motor), creating mechanical power flowing along the drive shaft 30 to the drive shaft 2, to the transmission 3 and flowing until the wheels as already described. The hydraulic accumulator 6, the pump / motor 7 and the shaft 30 constitute a second power train "parallel" to the first power train.

At point 26 is indicated an engine control device, for example a fuel injection pump, which controls the supply of fuel to the engine 1, in response to a signal which is a function of the engine speed. The signal Es can be computed by a processor 18 or it can be a signal received directly from a rpm 40 sensor.

A control fitting for the operation of the vehicle includes a vehicle speed sensor, for example a rpm sensor 12, which detects the rotational speed of the drive shaft downstream of the freewheel clutch 4, a pressure sensor 16. for detecting the pressure inside the fluid pressure accumulator 6 and generating a signal Ps representative of the detected pressure and a power demand sensor 14, for example a sensor for detecting the position of the "accelerator pedal". A first processor 42 receives the signal Ps representative of the fluid pressure detected by the sensor 16 and compares that detected fluid pressure with a predetermined minimum fluid pressure and generates a demand signal FPs to the determination that the perceived fluid pressure is below the predetermined minimum fluid pressure. That demand signal FPs is sent to the pump controller 20 for the conversion of the pump / motor ~ to the second mode for operation as a pump, to store energy in the accumulator 6 in the form of a fluid pressure.

A second processor 44 determines an additional power according to the demand signal FPs and an engine output power as the sum of the perceived power demand 14 and the determined additional power. A third processor 46 determines the engine speed of the optimum efficiency in accordance with the determined overall engine output power, and with the perceived vehicle speed outputs a transmission signal Ts, indicative of the optimum engine speed determined at the motor speed controller 24. The controller 24 regulates the motor speed in response to the signal Ts by changing the effective diameter of the pulley 22 of the CVT 3. The processors 42, 44 and 46 can optionally be combined in a single microprocessor 18. including a memory 48. The signal Ts is determined by reference to a two-dimensional map stored in the memory 48 wherein the values for an optimum efficiency power and the motor speed are correlated. Knowing the desired engine speed and the vehicle speed of the sensor 12, the signal Ts is computed. This control system is in a similar way applicable to other modalities described here below.

An optional secondary motor 10 can still provide additional reserve power. In this case an electronically controlled clutch 11 is engaged through which the power of the motor 10 is supplied inside the system. Secondary motor 10 provides backup power for severe or repeated accelerations and for continuous operation to maintain speed on long-and / or steep slopes. The secondary motor 10 and the clutch 11 can be installed as shown (to supply power to the drive shaft 2) or to supply power to the drive shaft 9 directly. The motor 10 can be electronically ignited and the clutch 11 clutch in response to a signal SEs generated as a function, for example, of the position of the perceived "accelerator pedal" and of the detected accumulator fluid pressure. The clutch 11 serves to engage the secondary motor in the output speed of the primary motor. The primary motor 1 and the secondary motor 10, in combination, can be seen as a functional equivalent of a variable displacement motor.

When the zero power is demanded in the wheels, the vehicle is changed to a sliding mode per gravity downwards, in response to a signal Cs of the microprocessor 18-, by disengagement of the freewheel clutch 4. In this way the vehicle It is isolated from rotational frictional losses in the power train so that all the vehicle's kinetic energy is available to overcome rolling resistance and aerodynamic drag. The clutch 4 is normally engaged and disengaged only when the demand for zero power is detected by the sensor 14.

When the handler brakes, regenerative braking occurs, the kinetic energy is transferred from the wheels 5 past the clutch 4 through the transmission 3 along the drive shaft 2 to the pump / motor 7 (acting as a pump) . The pump / motor 7 pressurizes the fluid and therefore stores the energy in the accumulator 6 in the same manner as described above.

Through the fluid pressure in the accumulator 6, the pump / motor 7 operating in its first mode as a motcr can be used as a starter motor 1, thus eliminating the need for a conventional initiator motor.

The operation of the invention will be more clearly understood with reference to Figures 2A-2D. In the following discussion the term "optimum efficiency" refers to a speed and load range, for example, (power) at which the efficiency of motor 1 is reasonably considered close to its optimum efficiency, between points A and B.

Figure 2A is a graph which represents cases (mode 1) when the power demanded is greater than the deliverable at optimum efficiency by motor 1 (point B) in the mode of figure 1. In this case, that part of the load exceeding B is provided by the motor / pump 7 (acting as a motor) while the motor 1 provides the rest. In the modes where the motor / pump axes and the motor are not engaged, the motor 1, the pump / motor 7, and the transmission input shaft 3 will operate at the same speed. A clutch arrangement or gear reduction can be incorporated there without changing the basic function in this way.

Figure 2B illustrates the operation of the system of Figure 1 in a mode 2, for example when the power demand of the engine 1 is within the optimum efficiency range (between the power levels A and B! This power demand of the motor 1 was determined by a microprocessor 18 considering the power demanded by the handler 14 and if the power must be supplied or extracted from the accumulator 6. If there is no need to return to fill the accumulator 6, all the power is provided by the motor 1, and the pump / motor 7 is set to zero displacement (for example neutral position) by the controller 20 where neither pumping fluid into the accumulator 6 nor providing power To the system.

Figure 2C illustrates the situation where the motor 1 can satisfy the power demand of the handler, and there is a need (for example the energy level of the accumulator reached a predetermined minimum level, but the motor 1 can operate at a level of optimum power point (b)) or desire (for example, need to operate the motor at its optimum efficiency as indicated by the power demand point of the handler (a)) to refill the accumulator (mode 3). Even when the demanded road load is represented by any of points (a) or (b) shown in Figure 2C, the power output of the motor is increased along the optimal efficiency line to a point at which Sufficient excess power is generated, illustrated here by point (c). This excess power that does not go to the road load is fed into the pump / motor 7 (acting as a pump) which stores it in the accumulator 6 for future mode 1 or mode 4 events.

Figure 2D illustrates mode 4 where an unusually small road load is experienced. In this case, the motor can not deliver such a small amount of power to an acceptable efficiency and there is a significant pressure in the accumulator 6. The fuel flow to the motor 1 is turned off, and the pump / motor 7 (acting as a motor) It provides the power by itself.

Regenerative braking can be thought of as an extension of mode 4 (Figure 2D), in which the power demand is zero and the vehicle must decelerate at a rate greater than the rolling resistance and aerodynamic drag can provide. The handler activates the brakes, which in turn activates the pump / motor 7 (acting as a pump) which pressurizes the fluid as previously described using the kinetic energy of the vehicle taken through the drive shaft 2, the transmission 3 and the lower drive shaft 9.

This results in a deceleration similar to that caused by frictional braking, but energy is saved in accumulator 6 rather than discarded.

As an alternate modality adapted for the operation which is expected to involve a more extensive and circulated stopping as shown in figure 3. In the circulation with continuous stop and advance, a mode is invoked in which the pump / motor drives directly the vehicle without engine assistance. In this case a clutch 8 is provided between the motor 1 and the pump / motor 7 so as to disconnect the motor 1 in this mode and avoid the friction associated with the operation of the motor 1.

In Figure 4 there is still another embodiment, wherein a second pump / motor 13 is provided between the transmission and the wheels. This configuration will allow the regenerative braking energy to proceed through the second motor / pump 13 directly to the accumulator 6 without incurring frictional losses when passing through the transmission 3. If the second pump / motor 13 pulls when it is in neutral is sufficiently low, the second pump / motor 13 can remain in line directly geared to the wheel drive 9 during all driving modes. One option to eliminate this "neutral" drag can be to add a clutch between the second pump / hydraulic motor 13 and the wheel drive 9. Since the second pump / motor 13 can also provide power to the wheels in. acceleration and circulation modes, this allows the size of the pump / motor 7 to be reduced first. The smaller size of the pump / motor 7 allows the pump / motor to be operated selectively so as to better optimize the size of the chosen motor with the power that is being demanded by the wheels, improving the average efficiency. This is specifically important for urban traffic where low and modest accelerations are frequent modes of circulation and a smaller pump / motor 7 can supplement the primary motor 1 more efficiently for power increases, for example, than a motor / pump more. big. The addition of the second pump / motor 13 to handle high acceleration rates and steep and steep slopes will also allow a significantly smaller transmission, which is important for CVTs. For steep slopes, the motor 10 will be activated and the pump / motor 7 can operate as a pump driving the motor / pump 13 as a motor. Alternatively, a pump may be attached to the engine 10, eliminating the clutch 11, to supply a sustained power through the motor / pump 13 as a motor.

Another embodiment shown in figure 5 includes the second motor 10 clutched directly into the drive shaft 9 either up or down the freewheel clutch 4, rather than behind the primary motor 1 as in the embodiments of the figures 1, 3, and 4. This arrangement allows the energy produced by the second motor 10 to pass directly to the wheel 5 without incurring losses in the components upstream of the drive line, and allows a smaller transmission 3 and, if it is downstream, a smaller freewheel clutch 4. In any location, the second motor 10 supplies power for various purposes, including but not necessarily limited to providing additional power for a sustained hill climb, providing additional acceleration power. during moments of extremely hard acceleration, providing an emergency launching power in the event of an exhaustion of the accumulator, providing backup power - for normal acceleration in order to allow a reduced accumulator or pump / motor size, and for selective operation to better match the chosen motor size with the road load demand.

A possible modification of the mode shown in Figure 3 would be to suppress the transmission 3 and launch the vehicle with the pump / engine 7 through the proper use of the freewheel clutch 4.

A possible modification of the mode shown in Figure 4 would be to suppress the transmission 3 (and optionally the clutch 12) and add a clutch between the pump / engine 13 and the drive wheel 9. The vehicle would be launched with either the pump / motor (holding clutch 8) or pump / motor 13. At vehicle speeds above a specified minimum (for example 20 miles per hour), a motor 1 would be engaged and would provide direct shaft power, and the operation would proceed as previously indicated. This configuration will eliminate any risk of accumulator pressure depletion.

The logical flow for control by the microprocessor 18 will now be described with reference to Figure 6 of the drawings. Figure 6 is a flow chart showing the flow of control processing by a microprocessor or computer unit 18. In step SI a determination is made according to a signal from the braking sensor 50 of whether the brakes are engaged or not. do not. If the brakes are engaged (Y), the engine 1 is turned off or disconnected to allow regenerative braking with the pump / motor 7 operating as a pump to convert that braking energy into fluid pressure stored in the accumulator. In step S2 a determination is made as to whether or not the braking is required in addition to the regenerative braking. If required, the friction brakes are engaged. In step S3 a determination is made, according to the signal from the sensor 14, of whether or not the power is demanded by the handler. If the power is not demanded, the processing proceeds to step S4 wherein the accumulator pressure, determined as a function of the sensor signal 16, is compared to a predetermined minimum value for the accumulator pressure and, if it is below that By default, the motor is allowed to remain running with the pump / motor 7 operating as a pump to convert the motor power into stored energy in the form of fluid pressure. If the pressure comparison of step S4 determines that the perceived fluid pressure is above the predetermined minimum, the motor is turned off or disconnected and the control processing cycle is restarted. If a determination is made in step S3 that the power is demanded by the handler, the control processing proceeds to step S5 where the determination is made whether the motor is operating or not at an optimum efficiency for the output power. defendant and the speed of the vehicle. This determination is made with reference to a map or curve for optimum efficiency on a scheme of torsional force of engine output (eg load) against vehicle speed (each point on the curve represents a single power level) stored in the memory 48. If determined in step S5 - that the motor 1 is operating within an optimum efficiency range, the control processing proceeds to step S6 where a determination is made as to whether the perceived fluid pressure is or not above a predetermined very high value for fluid pressure. If the fluid pressure is found to be above the very high value predetermined in step S6, the power demanded by the handler will be supplied by the operation of the pump / motor 7 as a motor operated by fluid pressure released by the accumulator 6. If the accumulator or fluid pressure is not at a very high predetermined value the control processing proceeds to step S7 where the perceived fluid pressure is compared against a very low predetermined value for the fluid pressure and, if is below a predetermined low value, processing proceeds to step S8 where the determination is made regarding the availability of additional motor power and, if the additional motor power is available, then that additional motor power is used to store the additional fluid pressure in the accumulator with the operation of the pump / motor 7 as a pump. If the perceived fluid pressure is not below a very low predetermined value in S7 or if the motor power is determined as that available in step S8, control processing returns to the beginning. If, in step S5, it was determined that the motor 1 is not operating within an optimum efficiency range, the control processing proceeds to step S9 where the determination is made as to whether the motor is operating or not at a range of optimum efficiency below. If the determination of step S9 is positive, the processing proceeds to the SIO step where the perceived fluid pressure is compared with against a predetermined low value for the fluid pressure and if, below that predetermined low value, the power of the fluid is measured. The motor is increased and the pump / motor 7 operates as a pump to increase the fluid pressure inside the accumulator 6. If, in step SIO, it was determined «that the accumulator pressure is not" low ", the power demand is satisfies by driving the power train with the operation of the pump / motor 7 as a motor driven by the fluid pressure released by the accumulator 6.

If in step S9 it was determined "that the motor is not operating below the range for optimum efficiency, for example, it is operating above the range for optimum efficiency, processing proceeds to the Sil step where the perceived fluid pressure is compared against a predetermined "very low" value for fluid pressure. If it was found to be below that "very low" value for the fluid pressure in step Sil, the secondary motor 10 is turned on and the clutch 11 (in the modality of figure 1) is hooked so that "both engines operate in series to drive the vehicle. If the determination in step Sil is positive the processing proceeds to step S12 where a determination is made as to whether there is a need for more power. If a need for additional power is determined, the pump / motor 7 is operated as a motor to provide that additional power. If in step Sil, a determination is made that the perceived fluid pressure is above the predetermined "very low" value for the fluid pressure, the secondary motor does not turn on and instead, the vehicle is driven by the primary motor 1 and the pump / motor 7 operating as a motor.

The notes for figure 6 are read as follows- (1) set continuously variable transmission ratio (CVT) and displacement of hydraulic pump to achieve the desired degrees of braking, until the slip wheel drive. (2) put the relation «CVT to achieve an optimum motor speed / power. (3) put the CVT ratio and hydraulic motor displacement to achieve optimum efficiency power. (4) put the CVT relationship to achieve the motor speed for maximum power.

The invention can be involved in other specific forms without departing from its spirit or essential characteristics. The present embodiments are therefore considered in all respects as illustrative and not restrictive, the scope of the invention being further indicated by the claims rather "than limited by the foregoing description and all the changes" which fall within the scope and scope of the invention. range of the equivalents of the claims and therefore try to be covered there.

Claims (16)

R E I V I N D I CA C I O N E S

1. A hybrid power train vehicle comprising: a vehicle frame; the drive wheels mounted rotatably on said vehicle frame; a primary motor, mounted on said vehicle frame, to provide motor power on an output shaft; power storage means, mounted on said vehicle frame, for storing and releasing power generated by said primary motor; the first power train means for transmitting said motor power to the drive wheels, said first drive train means including a transmission having adjustable speed input and output; reversible means for selectively transmitting, in a first mode, said motor power to said power storage means or, operating as a motor in a second mode, transmitting the stored power from said power storage means to said first drive train; second drive train means, said reversible means connecting said first drive train means, for, in said first mode, transmitting said stored power to said first drive train means and for, in said second mode transmitting said power of motor to said reversible means; vehicle speed sensor means for sensing vehicle speed; stored power sensor means for sensing a quantity of power stored within the power storage means; means of perception of power demand to perceive the demanded power of the vehicle by the driver; comparative means for comparing said stored amount of stored power with a predetermined minimum amount of stored power and generating a demand signal for determining "that the perceived amount is below said predetermined amount; means for determining power output to determine an additional power increase according to the demanded signal and for determining an output power of the motor as a sum of the perceived power demand and the additional power increase; motor speed control means for controlling the rotational speed of said output shaft by changing the perceived speed of said transmission in response to the transmission signal; means for determining the engine speed to determine an optimum efficiency engine speed in accordance with said determined engine output power and said perceived vehicle speed and for outputting the transmission signal indicative of the determined engine speed, to said means engine speed control; engine load control means for controlling said engine power by controlling the fuel supplied to said primary engine in response to the transmission signal; Y mode control means for converting the operation of said reversible means between the first and second modes that respond to the signal demand.

2. A hybrid power train vehicle, as claimed in clause 1, characterized in that it comprises: a secondary motor; a secondary motor clutch for connecting an output of said secondary motor to said first drive means in response to the perceived power demand.

3. A hybrid power train vehicle, as claimed in clause 2, characterized in that said comparing means compare the perceived power demand with a predetermined maximum power for said primary motor and generates a command signal for starting said secondary motor and for engaging said secondary motor clutch when the perceived power demand exceeds said predetermined maximum power.

4. A hybrid power train vehicle, as claimed in clause 3, characterized in that said command signal is generated only with the determination that the perceived amount of stored power is below said predetermined amount.

5. A hybrid power train vehicle, as claimed in clause 1, characterized in that said freewheel clutch interposed between said transmission and said drive wheels for disengaging said drive wheels from said first drive train in response to a signal indicative of zero perceived power demand.

6. A hybrid power train vehicle, as claimed in clause 1, characterized in that it comprises a memory containing stored map correlative values for said optimum motor speed and the motor output power; and where said motor speed determination means applies said determined motor output power and said perceived vehicle speed to said map to determine the optimum efficiency motor speed.

7. A method for controlling a vehicle equipped with a hybrid powertrain propulsion system including the drive wheels, a primary motor for energizing the drive wheels, the reversible drive means, the power storage means for storing the engine power generated by said primary engine, a transmission having an adjustable speed input and speed output and motor speed control means for changing the input speed of said transmission, said method comprises: perceive the speed of the vehicle; perceiving a quantity of power stored within the power storage means; perceive the power demanded of the vehicle by a handler; supplying power from the power storage means, through the reversible driving means, using the reversible driving means as a motor for driving said driving wheels in response to a signal indicative of a demanded power above the motor output primary; transmitting a portion of said output power of the primary motor into the power storage means, using the reversible driving means, responding to a perceived amount of stored power lower than a predetermined value; comparing the perceived amount of stored power with a predetermined minimum value and generating a demand signal with the determination that the perceived amount of stored power is below the predetermined low value; determining an additional output power according to the demand signal and determining an engine output power as the sum of the perceived power demand and the additional output power; control the rotational speed of the primary motor by changing the input speed of the transmission in response to a transmission signal; Y determine an optimum efficiency engine speed according to the determined engine output power and the perceived vehicle speed and take out the transmission signal according to the determined engine speed.

8. The method, as claimed in clause 7, characterized in that said propulsion system includes a memory containing a first stored map correlating values for the optimum engine speed and determining the engine output power, and a second map correlating values for the vehicle speed and said transmission signals, each of the transmission speeds representing a transmission speed ratio (gear to achieve an optimum motor speed; said determination of the optimum motor speed is by applying the determined motor output power and a perceived vehicle speed to said maps to select an optimum efficiency motor speed for a given motor output power and said vehicle speed perceived and to put the transmission signal. "10

9. A hybrid power train vehicle" comprising: a vehicle frame; 15 the drive wheels mounted rotatably on said vehicle frame; a primary motor, mounted on said vehicle frame, to provide motor power on an output shaft; a fluid pressure accumulator, mounted on said vehicle frame, for storing and releasing the fluid pressure; the first drive train means for transmitting said motor power to said drive wheels, said first drive train means includes a continuously variable transmission having at least one pulley of an effective variable diameter; reversible fluidic displacement means for, in a first mode, operating as a fluidically driven motor by the fluid pressure released by said accumulator, at an output motor power for said first drive train and for, in a second mode, operating as a pump driven by said first drive train to store said fluid pressure; "second drive train means, connecting said fluidic movement means with said first drive train means, for, in said first mode, transmitting said motor power to said first drive train means and for, in said second mode, transmitting the motor power to said fluidic displacement means; vehicle speed sensor means for sensing vehicle speed; pressure sensor means for sensing the fluid pressure inside said accumulator; means of perception of power demand to perceive the demanded power of the vehicle by the driver; comparative means for comparing said perceived fluid pressure with predetermined minimum fluid pressure and generating a demand signal with the determination that said perceived fluid pressure is below said predetermined fluid pressure; means for determining power output to determine an additional power increase according to the demanded signal and for determining an output power of the motor as a sum of the perceived power demand and the additional power increase; motor speed control means for controlling the rotational speed of said output shaft by changing the effective diameter of said pulley in response to the transmission signal; means for determining the motor speed to determine an optimum efficiency motor speed according to the determined motor output power and said perceived vehicle speed and to output the transmission signal, indicative of the determined motor speed, to said engine speed control means; motor speed control means for controlling said motor power by controlling the fuel supplied to said primary power in response to said transmission signal; Y mode control means for converting the operation of said fluidic movement means between said first and second modes responsive to the demand signal and for varying the displacement of said fluidic displacement means in response to the perceived fluid pressure.

10. A hybrid power train vehicle, as claimed in clause 9, characterized by includes: a secondary motor; a secondary motor clutch for connecting an output of said secondary motor to the first drive means in response to the perceived power demand.

11. A hybrid power train vehicle, as claimed in clause 10, characterized in that said comparing means compare the perceived power demand with a predetermined maximum power for said primary motor and generates a demand signal to ignite said motor. secondary motor and to engage said secondary motor clutch when the perceived power demand exceeds said predetermined maximum power.

12. A hybrid power train vehicle, as claimed in clause 11, characterized in that said command signal is generated only with the determination that the perceived fluid pressure is below said predetermined fluid pressure.

13. A hybrid power train vehicle, as claimed in clause 9, characterized in that it comprises a freewheel clutch interposed between said transmission and said drive wheels for disengaging said drive wheels from the first train of power. drive in response to a signal indicative of a perceived power demand of zero.

14. A hybrid power train vehicle, as claimed in clause 9, characterized in that it comprises a memory containing stored map correlative values for said optimum motor speed and the motor output power; and wherein said motor speed determination means applies said determined motor output power and said perceived vehicle speed to said map to determine the optimum efficiency motor speed.

15. A method for controlling a vehicle using a hybrid powertrain propulsion system including the drive wheels, a primary motor for energizing the drive wheels, a reversible fluidic displacement means, an accumulator for accumulating pressure fluid, a continuously variable transmission having a moving pulley of an effective variable diameter and a controller to mechanically move that pulley to change the effective diameter, said method comprises: perceive the speed of the vehicle; perceive the fluid pressure inside the accumulator; perceive the power demanded of the vehicle by a handler; supplying said fluid pressure from the accumulator, through the reversible fluid displacement device, to use the reversible fluid displacement device as a motor for driving said drive wheels in response to a signal indicative of a demanded power above that produced by the primary motor; pumping the fluid pressure inside the accumulator, using a part of the output power of the primary motor to drive the reversible fluid displacement means as a pump, in response to a perceived fluid pressure lower than a predetermined value; comparing the perceived fluid pressure with a predetermined minimum fluid pressure and generating a demand signal with the determination "that the perceived fluid pressure is below the predetermined low fluid pressure; determining an additional output power according to the demand signal and determining an engine output power as the sum of the perceived power demand and the additional output power; controlling the rotational speed of the primary motor by changing the effective diameter of the mobile pulley in response to a transmission signal; Y determine an optimum efficiency engine speed according to the determined engine output power and the perceived vehicle speed and take out the transmission signal according to the determined engine speed.

16. The method, as claimed in clause 15, characterized by the propulsion system including a memory containing a first stored map correlating values for the optimum engine speed and determining the engine output power, and a second map correlating values for the vehicle speed and said transmission signals, each of the transmission speeds representing a transmission speed ratio (gear) to achieve an optimum motor speed; and where said determination of the optimum motor speed is by applying the determined motor output power and a perceived vehicle speed to said maps to select an optimum efficiency motor speed for a given motor output power and said vehicle speed perceived and to put the transmission signal. E S U M E N An engine output speed is controlled for optimum efficiency by adjusting the input speed for a continuously variable transmission (CVT). Where an excess of the energy provided by the motor is required, the additional energy is put into the power train from a fluidic motor driven by the fluid pressure stored in an accumulator. In driving conditions where the engine, operating at optimum efficiency, produces energy in excess of that demand by the vehicle, the fluidic motor is inverted for operation as a pump and the excess motor energy is used to drive the motor. pump and store the energy in the accumulator in the form of fluid pressure. A CPU determines the required power output of the motor as a sum of that indicated by a sensor that senses the demanded power of the vehicle by a handler and an increase in power required to maintain the accumulator pressure above a threshold amount.