MXPA98002625A - Transmission continually your - Google Patents

Abstract

The present invention relates to a drive train for a vehicle having the front and rear wheels include a fluidic motor and a pump interconnected in a continuous circuit, with a conduit connecting the fluidic motor inlet to the pump outlet and a second conduit connecting the pump inlet to the outlet of the fluidic motor. A liquid / gas fluid accumulator is in fluid communication with the first conduit and a low pressure reservoir is in fluid communication with the second conduit. An engine is used to drive the pump. The sensors are included to detect the pressure inside the accumulator and the demanded power of the vehicle by the driver and, optionally, the speed of the vehicle. A motor controller controls the displacement of the fluidic motor in accordance with the perceived power demand and a pump controller controls the displacement of the pump in response to the signal of the detected pressure

Description

CONTINUOUSLY SOFT TRANSMISSION BACKGROUND OF THE INVENTION Field of the Invention; The field of the invention is that of transmissions for motor vehicles that provide increased fuel efficiency.

The previous art; Conventional transmissions used in motor vehicles transmit torsional force from the engine to the wheels through two means: (1) the predominant torsional force transfer is "handover", for example, in response to the driver's command of more power, the fuel flow rate is increased to the engine, the torsional force of the engine is increased and the increased torsional force is "passed up" to the wheels (see mode 1 for a map of typical engine-line torsional force) X "shown in Figure 1); and (2) when the handler's command for more force exceeds that which the motor can deliver at its initial speed, the handler must change the transmission to a lower gear (either manually or by triggering the change in an automatic transmission). ") to increase the motor speed (2-line mode" Y "in Figure 1, for example). Since the energy for the wheels at a given engine speed is proportional to the torsional force of the engine times the engine speed, the force to the wheels is increased by either increasing the torsional force of the engine (fuel flow rate) at a given engine speed) and / or by increasing the engine speed. There are two main disadvantages of such transmissions: (1) the motor is usually operating in mode 1 and therefore supplies torsional force at an average efficiency much lower than the optimum available (for example, in Figure 1 point A represents a value average while point B represents the optimum available efficiency at this speed); and (2) when a gear change is required, there is an interruption in the supply of torsional force to the wheels, manifested as a "jerk or jerk". Automatic transmissions soften this "pull" through a torsional force converter; however, the result is increased inefficiency.

Much work has been devoted to replacing conventional transmissions and their inherent disadvantages. This work has focused largely on continuously variable transmissions (CVT). Ideally, with a continuously variable transmission, one motor will operate along the "Z" line, the optimum efficiency line as shown in Figure 1. Continuously variable transmission designs include mechanics (eg variable-ratio pulleys) , the electric (an electric generator driven by the engine "activates" an electric motor connecting the wheels - the modern train locomotives use this design) and hydraulic that operates very similar to the electrical design. These designs offer some improvements but are still based on mode 1 (line "Xp in Figure 1 - fuel rate increased at a given speed or, more generally when the speed is changed, flow rate increased by combustion event), As the means to increase the engine speed to increase the force to the wheels, however, the operation along the optimal torsional force curve shown as the line "Z" in Figure 1, leaves little remaining torsional force available above this optimum to rapidly increase the engine speed (for example by accelerating the rotating mass of the engine while exceeding the increased friction) to respond quickly to the order of the increased force handler to the wheels.The rapid force response is a critical performance characteristic of the vehicle from the perspective of the client / driver.

There are two currently recognized options that improve the response of a continuously variable transmission. The first option initially reduces the available torsional force for the wheels and applies this torsional force to accelerate the engine at the increased speed needed. Nevertheless, this first option is commercially unacceptable because it results not only in a hesitation, but in a real loss of strength for the wheels, which is completely contrary to the order of the driver of more strength. The second option reduces the standard operating curve down from the optimum so that more torsional force is available for the mode 1 function (see line "W" in Figure 1), thus resulting in an additional efficiency exchange while The force response of conventional transmissions that can fully utilize both mode 1 and mode 2 is not yet achieved.

SYNTHESIS OF THE INVENTION Therefore, it is an object of the present invention to provide a third option that not only fully resolves the force response restriction to conventional CVT designs, but also does so without the need to increase the torsional force of the motor (mode 1). ) for the necessary motor speed increase, and without the associated inefficiencies.

Another object is to provide a power train for a vehicle which reduces emissions of NOx, C02 and other pollutants from motor vehicles.

It is yet another object of the present invention to provide a continuously variable transmission which: (1) gives a continuous, smooth and rapid response at the command of a handler to increase power to the wheels; and (2) it does so without the need to use increased engine torque (and therefore fuel consumption per engine combustion cycle) to increase engine speed, such increased engine speed being required to meet the new level of increased power required by the wheels.

Yet another object of the present invention is to satisfy the aforementioned objectives while allowing engine operation to be maintained at or near the optimal efficiency curve for the engine.

Still another object is to provide the functions mentioned above by initially reducing the power supplied by the motor to the wheels, while still providing increased power to the wheels in response to the command of the driver.

An additional object is to use multiple drive motors and for hybrid applications, multiple generators (pumps), to maximize the efficiency of the drive train.

In view of the accomplishment of the aforementioned objectives, the present invention provides a drive train for a vehicle which has the front and rear wheels where the drive train has at least one fluidic motor and one pump interconnected in a circuit of fluid with a conduit connecting the outlet of the pump to the inlet of the fluidic motor and a second conduit connecting the output of the fluidic motor to the inlet of the pump. A motor smaller than conventional, sized according to the average torsional force demand on the vehicle, serves to drive the pump. A fluid accumulator, containing pressurized gas and a quantity of hydraulic fluid in the circuit, is in communication with the first conduit and a liquid reservoir is in fluid communication with the second conduit. A pressure sensor is provided to detect the fluid pressure inside the accumulator and to generate a pressure signal representative of the detected pressure. The power demand is sensed by a sensor which detects the position of the accelerator pedal or the position of the regulator as an indication of the vehicle's power demand by the driver. A motor controller controls the displacement of a fluid motor in accordance with the perceived power demand and a pump controller controls the displacement of the pump in response to the pressure signal.

An electronic control unit (ECU) receives signals representative of the vehicle speed, the accumulator pressure and the power demanded by the driver and the output control signals to the pump controller and the motor controller to control the displacements thereof. In an embodiment employing plural fluidic motors, the electronic control unit operates to select for operation a fluid motor displacement or combination of different displacements for different motors better suited for the vehicle power demand detected.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph of a percentage of the torsional force of the engine against the engine speed for a typical engine, with curves showing the percentage of fuel efficiency; Figure 2 is a schematic diagram of a drive train according to the first embodiment of the present invention; Figure 3 is a schematic diagram of a second drive train mode of the present invention.

Figure 4 is a graph of the plate angle of a typical pump or motor, which can be used as a component of the drive train of the present invention, against the operating pressure with curves showing the percent efficiency; Figure 5 is a schematic diagram of a third embodiment of the drive train of the present invention; Figure 6 is a schematic diagram of a fourth embodiment of the drive train of the present invention; Figure 7 is a schematic diagram of a fifth embodiment of the drive train of the present invention; Figure 8 is a schematic diagram of a sixth embodiment of the drive train of the present invention, and Figure 9 is a schematic diagram of the control unit of the present invention showing the input signals and the output signals.

DESCRIPTION OF PREFERRED INCORPORATIONS Figure 2 shows a first preferred embodiment where a hydraulic CVT is combined with an accumulator, to provide a continuously hydraulic smooth transmission (hereinafter "CST"). An engine 1 delivers power to a hydraulic pump 2, which in turn delivers a flow of pressurized hydraulic fluid through line 3 to a hydraulic motor 4. The hydraulic motor 4 transforms the hydraulic power into torsional force which is supplied to the wheels 5. An accumulator 6 is then connected to the line 3 and serves as an additional supply source for pressurized hydraulic fluid flow to the hydraulic motor 4. The accumulator 6 contains a volume of gas and, when the fluid is pumped Hydraulic in accumulator 6, the gas pressure increases and the energy is stored. When this stored energy is required, the hydraulic fluid is allowed to exit the accumulator ß and supply power to the hydraulic motor 4. Since the flow leaving the hydraulic fluid from the accumulator 6 can be at a very high rate, the accumulator can be sized to store only a small amount of energy, and this energy can be delivered in a very short period of time. Therefore, the system can be considered a high power device. A reservoir of low pressure hydraulic fluid 7 supplies the fluid when the coil 6 is being charged and stores the fluid when the accumulator 6 is supplied power to the hydraulic motor.

Again referring to Figure 1, if a vehicle engine is operating at point C and the driver issues a power command to the wheels corresponding to point D, for example, press the accelerator pedal 26 (Figure 2), the The displacement of the hydraulic motor is increased by the motor controller 22 to increase the power to the wheels 5 to the level corresponding to point D in FIG. 1. The greatly increased flow associated with the increased motor displacement can not be supplied quickly to the motor 1 ( Figure 2) until its speed is increased (the previously described problem) and, therefore, the accumulator 6 supplies the increased hydraulic fluid flow while the engine speed is increased. Therefore, the CST delivers an almost instantaneous response to the request of the power driver for the wheels while maintaining the optimum motor operating characteristics, for example while allowing the motor to continue running at peak efficiency. The accumulator 6 may be small, just large enough to "fill" the flow of hydraulic fluid while the engine speed changes (usually less than five gallons and probably for most applications about one or two gallons).

In this preferred embodiment the pressure in the accumulator 6 is monitored by a pressure sensor 30. The pressure sensor 30 and the accelerator pedal position sensor 28 (or the regulator position sensor) send signals to an ECU 32 (see Figure 9) which in turn sends output signals for the control of the pump controller 20, the motor controller 22 and the fuel supply 24. Therefore the change in the position of the pedal detected by the sensor 28 is correlated with the pressure of the accumulator 6 detected by the pressure sensor 30 to determine a new displacement setting for the pump 2 and a signal is sent from the ECU 32 to the controller 22 to return the displacement of the motor 4 to the new one value. An increase in the displacement of the motor 4 (when an increased pedal depression is sensed) will result in a drop in system pressure and in the accumulator 6 and, therefore, the ECU 32 sends a signal to the pump controller 20 to decrease the displacement of the pump 2 according to the drop in pressure so that the speed of the motor 1 will increase rapidly corresponding to the new power demand. When the motor 1 reaches the proper speed, the ECU 32 sends a signal to the pump controller 20 to increase the displacement of the pump 20, satisfying the fluid power requirement and again gaining the fixed point pressure of the system.

The speed increase of the motor can be achieved by one or by a combination of several means. The motor automatically adjusts to a drop in system pressure by increasing the speed, thereby maintaining an essentially constant torsional force output. However, perhaps the most cost-effective means of increasing the engine speed is to reduce the displacement of the pump 2 by the controller 20. The combination of the reduced system pressure associated with the increased flow through the motor 4 and the reduced displacement of pump 2 allows the output power of the motor to be changed more to accelerate the motor. The power supplied to the system from the motor 1 is directly proportional to the displacement of the pump 2 and to the system pressure. Similar cost effective means to increase the engine speed will be an engine "lighter" (either hydraulic or electric) which, in combination with a reduced system pressure, will rapidly accelerate the engine to the new required speed. Of course, the traditional means of increasing engine speed by increasing the fuel rate (fuel amount per combustion event) through 24 (mode 1) can still be used, but this would no longer be required.

Power reduction, for example, going from point D to point C in Figure 1, is handled in a manner similar to power increases except for an important difference. As the displacement of the motor 4 decreases (Figure 2), the system pressure increases which inherently "drives" the motor speed to a new lower level required. There is, of course, no requirement for power response performance to decrease power demands.

In the present invention the accumulator can be replaced with an equivalent high power device, for example, an electric ultracapacitor in an electric drive transmission.

Figure 3 illustrates a second preferred embodiment of the invention which is a variation of the embodiment described in Figure 2. This second embodiment includes the concept of using more than one hydraulic motor to optimize the efficiency of power delivery to the wheels , taking into consideration the extremely wide range of power speed required in the wheels of motor vehicles. Even when a large motor is required for fast acceleration of the vehicle, such a large motor will not operate efficiently at more common light accelerations and vehicle-ratio cruise modes. Figure 4 shows the percentage of efficiency on the operation map of a typical large hydraulic motor at a speed that will be geared to correspond to, for example, at a vehicle speed of 50 miles per hour. Point A corresponds to the power level that may be required for a fast-pass maneuver while point B corresponds to a typical cruise rod load. It is clear that in order to be able to satisfy the high power demand associated with a rapid acceleration, that the most common and therefore higher power consumption modes like the B point will not be satisfied with superior efficiency from a single motor. Therefore, the variation shown in Figure 3 allows the engine displacement control system to collect, among other motors 4, 4 'and 4", that respond to the driver's power demand detected by the position sensor of the engine. accelerator pedal 28 and the vehicle speed detected by the speed sensor 33, that the motor (or motors) having the size and displacement that most closely correspond to the higher efficiency for the detected vehicle speed and the power demand . The choice of the engine number is based on an exchange analysis of efficiency against cost.

The use of multiple motors also allows direct low-cost wheel drives and low-cost 4-wheel direct drive. Individual motors can activate each wheel (Figure 6), or direct wheel drive and differential drive can be combined (Figure 5). Therefore, the embodiment of Figure 5 includes motors 4, 4 'and 4"and motor controllers 22, 22' and 2", while the embodiment of Figure 6 includes motors 4, 4 ', 4 '' and 4 '' ', and the motor controller 22, 22', 22 '', and 22 '' '.

Figure 7 illustrates the main components of a fourth embodiment of the invention. Figure 7 shows the CST integrated in a hydraulic hybrid propulsion system which incorporates regenerative braking in an efficient and low cost way. The hydraulic motors 4, 4 'and 4"can easily be operated as pumps by reversing the flow of the hydraulic fluid to pump fluid from the low pressure tank 7 to the second accumulator 8, through the flow control valve 9, thereby recovering the kinetic energy when the vehicle is braked and stored in the accumulator 8 for later reuse, for example, for high power demands such as accelerations. The accumulator 8 is sized to be sufficient to store a complete braking event plus any reserve that is desired for an additional load leveling and the reduction in the size of the engine 1. A variation of this mode will be the combination of the two accumulators in a single unit.

Figure 8 illustrates a fifth embodiment which adds a second motor 10 and a pump 11 for a truck towing option and / or to allow yet another reduction in the size of the engine 1. The closer the engine 1 can be sized to the The vehicle's average power demand (for example, a power of 10 horsepower) will be more efficient on average and lower in cost.

The present invention allows a conventional vehicle to be equipped with a significantly smaller engine (for example 20-40 percent smaller) while maintaining the same vehicle performance (eg, acceleration and response) because this it can apply the maximum torsional force producible by the engine to the wheels compared to a much lower average value associated with conventional limited gear transmissions.

The present invention is especially suitable for hybrid vehicle applications (eg vehicles which have two or more power supplies available to drive the vehicle). This has all the advantages of the conventional vehicle application, in addition to allowing the primary power supply to be dimensioned even closer to the average power demand of the vehicle (compared to the peak power demand required with a conventional vehicle) , extracting much greater efficiency gains while maintaining the performance characteristics of a much larger engine (for example 20 horsepower rather than 120 horsepower).

The present invention also allows operation at or near the maximum efficiency of the engine by having the engine supply the necessary energy through a rapid increase in speed and allowing even a small engine to follow the driver's demand for torsional force. through a rapid change in engine speed without a hesitation or pull in the transition to increased torsional force in the wheels, while an increase in the fuel rate per combustion event is not required. This feature allows the use of a much lower and simpler cost engine fuel supply system where a constant or nearly constant amount of fuel is supplied for each combustion event.

Therefore, the present invention provides a continuously variable transmission (CVT) which is unique in its ability to transition to a greatly increased torsional force for the wheels without experiencing the conventional hesitation and / or pull associated with the change in engine speed. sudden "down shift" experienced in both the "standard" mechanical gear transmission and conventional "automatic" transmissions.

The invention may be involved in other specific forms without departing from the spirit or the essential characteristics thereof. The present embodiments should therefore be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes that fall within the meaning and scope of equivalence of the claims are therefore intended to be encompassed here.

Claims (8)

R E I V I ND I CA C I ONE S

1. A drive train for a vehicle having the front and rear wheels comprising: at least one fluidic motor, having an inlet and an outlet, for driving at least one of the wheels; at least one pump for producing a flow of hydraulic fluid to drive said fluidic motor, said pump having an outlet connected through the first conduit means to the inlet of said fluidic motor and an outlet connected through the second means of duct with the output of the fluidic motor; at least one motor for driving said pump at a variable speed; a fluid accumulator in fluid communication with said first conduit means and containing pressurized gas in a gas space and a quantity of the hydraulic fluid; at least one fluid reservoir in fluid communication with said second conduit means; a pressure sensor for detecting the pressure inside said accumulator and for generating a pressure signal representative of said detected pressure; energy demand prerequisite means for perceiving an energy demand by a vehicle driver for the acceleration or deceleration of the vehicle; an engine controller for controlling the displacement of said fluidic motor in accordance with the perceived power demand and the perceived pressure; Y a pump controller to reduce the displacement of said pump, in response to a fall the detected pressure is indicated by the pressure signal, thereby increasing the speed of a motor, and to increase the displacement of said pump when the motor speed increases to a predetermined value.

2. A drive train as claimed in clause 1, characterized in that it comprises: a plurality of fluidic motors connected in parallel, each having a different capacity and each having an input connected to said first conduit means and an outlet connected to said second conduit means; vehicle speed sensor means for detecting vehicle speed; plural motor controllers, each motor controller controls the displacement of one of said plurality of fluidic motors; Y computer means for receiving signals from said power demand sensor means, said pressure sensor and said vehicle speed sensor, for selecting the displacement of at least one of said fluidic motors in accordance with the received signals and for sending a control signal to the motor controller associated with said fluidic motor selected for the operation according to the perceived power demand and to send a control signal to the pump controller to change the displacement of said pump in response to said pressure signal.

3. A drive train as claimed in clause 1 characterized in that a fluidic motor drives a pair of the wheels and wherein said drive train further comprises the second and third fluidic motors, each of the second and third fluidic motors. drives a wheel other than that of said pair of wheels, and plural motor controllers, each motor controller controls one of said fluidic motors in response to the perceived power demand.

4. A drive train as claimed in clause 1 further characterized in that it comprises the second, third and fourth fluidic motors, each of said fluidic motors driving one of the wheels, and a plurality of motor controllers, each of said Motor controllers control the displacement of one of said fluidic motors in response to the perceived power demand.

5. A drive train as claimed in clause 1 characterized in that it comprises a second pump and a second motor for driving said second pump, said second pump has an outlet in fluid communication with said first conduit means and an input in communication of fluid with a second fluid reservoir, said motor being dimensioned to provide the average power demand of the vehicle at a high efficiency and said second motor being of an essentially larger size than that one motor.

6. A drive train as claimed in clause 3, characterized in that each of said second and third fluidic motors has a capacity less than that of a fluidic motor.

7. A drive train as claimed in clause 2 characterized in that said plurality of fluidic motors are connected in parallel and each has an input connected to said first conduit means and an outlet connected to said second conduit means.

8. A method for operating a hybrid vehicle having at least one combustion engine, a pump driven by that one engine, at least one fluidic motor mechanically connected to at least one driving wheel of the hybrid vehicle and fluidically connected to said fluidic engine with a hydraulic fluid circuit circulating therebetween, and a pressure accumulator in fluid communication with said circuit, said method comprises: detect engine speed; detect the fluid pressure inside the accumulator; perceive the demand for power on the vehicle; changing the displacement of a fluidic motor in response to the perceived power demand and the detected fluid pressure to satisfy the power demand and to maintain at least a minimum pressure with the accumulator; and controlling the displacement of said pump, in response to the detected pressure, to maintain the detected engine speed within a predetermined range based on the efficiency of the engine. E S U M E N A drive train for a vehicle having the front and rear wheels includes a fluidic motor and a pump interconnected in a continuous circuit, with a conduit connecting the inlet of the fluidic motor to the outlet of the pump and a second conduit connecting the inlet of the pump at the outlet of the fluidic motor. A liquid / gas fluid accumulator is in fluid communication with the first conduit and a low pressure reservoir is in fluid communication with the second conduit. An engine is used to drive the pump. The sensors are included to detect the pressure inside the accumulator and the demanded power of the vehicle by the driver and, optionally, the speed of the vehicle. A motor controller controls the displacement of the fluidic motor in accordance with the perceived power demand and a pump controller controls the displacement of the pump in response to the signal of the detected pressure.