Abstract:
A continuously variable transmission for a hydraulic mechanism in hybrid cars with recovered power-split energy mainly comprises a multi-function planet differential gear train pump and a hydraulic variable pump (motor). The planet differential gear train pump provides a hydraulic constant pump, and a planet gear system thereof provides a speed-adjustable function as well as a speed-collecting function. Thereby, the planet differential gear train pump of the present invention is used to substitute the conventional planet gear system and the hydraulic constant pump in the continuously variable transmission.

Description:
CROSS-REFERENCE(S) TO RELATED APPLICATION(S) 
     This application claims the benefit of Chinese Application 201010198109.2, filed Jun. 2, 2010, which is hereby incorporated by reference, in its entirety. 
     BACKGROUND 
     1. Field 
     The present invention relates to a continuously variable transmission for a hydraulic mechanism in hybrid cars with recovered power-split energy. A multi-function planet differential gear train pump is mainly adopted for further connecting to a friction brake, a hydraulic accumulator, a pressure sensor, a flow sensor, and a hydraulic valve controlling circuit so as to establish afore continuously variable transmission. Obviously, a hydraulic machinery composite transmission is provided along with a safe buffer and a buffer coupling as well as functions like recycling braking energy, storing hydraulic energy, recovering power, and operating in the continuously variable transmission. The present invention allows a car to reduce 20%˜40% driving power and to recycle more than 80% braking energy. If the traditional braking system malfunctions, the car could be still cushioned and braked by retrieving inertia kinetic energy. Thereby, the inertia kinetic energy is stored in the accumulator in a means of the potential energy of hydraulic static pressure. Preferably, the stored energy is provided for starting and accelerating the car. The present invention is especially suited to cars or buses that are often halted in the city. 
     2. Description of Related Art 
     The published continuously variable transmission with power-split energy is mainly composed by a hydraulic constant pump (motor), a hydraulic variable pump (motor), and a planet gear system. Such transmission is however bulky, the performance thereof is weak, and the structure of the same is adversely heavy. Moreover, noise is easily generated in afore transmission and this transmission merely provides a basic function. Even worse, the installation of the conventional transmission is difficult, so it is hard to be popular. For example, the hydraulic constant pump (motor), the hydraulic variable pump (motor), and the planet gear system provided by the Sundstrand Company in the U.S.A. further cooperate with two sets of friction clutches and four pairs of gear sets. Herein, the cooperation contributes to a continuously variable transmission for power-split hydraulic mechanism with parallel shafts DMT25. However, this transmission is also bulky and heavy, the function thereof is simple, and the installation thereof is still complicated. As a result, the company does not produce the same transmission anymore. 
     BRIEF SUMMARY 
     The present invention is to solve shortcomings existing in the conventional hydraulic mechanism with the power-split system such as the bulky dimension, the weak performance, the heavy structure, the simple function, the annoying noise, and the difficult installation. Accordingly, the present invention adopts a planet differential gear train pump and a hydraulic variable pump of through shaft to connect with a friction brake, hydraulic accumulators, a pressure sensor, a flow sensor, and a hydraulic valve controlling circuit so as to establish the desired continuously variable transmission for the hydraulic mechanism with recovered power-split energy. 
     Solving the conventional disadvantages, the applicant utilizes a published and patented product “A MULTI-FUNCTION DRIVING UNIT FOR HYBRID CARS”, under the Chinese patent no. ZL. 2009201680 53.9. Herein, the planet differential gear train pump in the present invention provides properties that used to be contained in the conventional hydraulic constant pump (motor) and the planet gear system so as to offer a speed-adjustable function as well as a speed-collecting function. Thus, the conventional planet gear system and the hydraulic constant pump (motor) in the hydraulic mechanism with the power-split system of the continuously variable transmission are replaced. Wherein, the hydraulic variable pump (motor) of through shaft is substituted for the conventional hydraulic variable pump (motor). The hydraulic variable pump (motor) of through shaft further coaxially connects to a power input shaft or a power output shaft of the planet differential gear train pump, so that a speed-adjustable unit or a speed-collecting unit for a hydraulic mechanism with a power-split energy recovery system is provided within a single axis. This invention is not only able to provide a continuously variable transmission but also transform inertia kinetic energy of the car into hydraulic potential energy in the high pressure reservoir while the speed of the car is reduced and the car is to be stopped. When the car is started and accelerated, the hydraulic potential energy stored in the high pressure reservoir is transformed into mechanical energy via the planet differential gear train pump and the hydraulic variable pump of through shaft in a motoring status so as to propel the car. When the car is in an economical cruising, the continuously variable transmission automatically adjusts the rotative speed of the motor according to different speeds per hour, thereby deciding an optimum working zone. 
     The present invention improves the transmission system in the cars. Namely, the power intensity of the transmission would be enhanced, and the rates of energy exchange, storage, and recovery would all be promoted. Further, the consumption of fuel would be economized by reducing the discharging amount of the motor but concurrently enhancing the working efficiency thereof. Moreover, the correlated recycling, storage, and recovery on the braking energy would all reach the maximum amount; the total efficiency of the recycling rate and the recovery rate would reach 70%, which is as many as four times provided by the conventional hybrid cars. If the conventional braking system malfunctions, the recycled braking energy is provided for stopping the car with a cushioning effect. At the same time, the inertia kinetic energy is recycled for being stored in the hydraulic accumulator in the form of static energy of hydraulic fluid. Thereby, the provided energy is sufficient for starting and accelerating the car. While the present invention is applied to the car that is mostly driven in the city, the consumed energy and carbon would be largely decreased. While the present invention is applied to the city bus, the bus economizes on fuel by 30%. That is, each bus economizes on fuel by more than 10 tons every year, the cost on the fuel of each bus is accordingly decreased by 70 thousand dollars, and the discharge of carbon dioxide is diminished by more than 20 tons. Apparently, the present invention benefits the economy and the society. 
    
    
     
       DESCRIPTION OF THE FIGURES 
         FIG. 1A  is a cross-sectional view showing the present invention in a speed-adjustable unit; in the figure, a power output shaft  1 , a hydraulic variable pump (motor)  2 , an entrance  3  for hydraulic variable pump (motor), an exit  4  for hydraulic variable pump, a bolt  5 , a planet differential gear train pump  6 , an inlet  7  of the planet differential gear train pump, an outlet  8  of the planet differential gear train pump, a friction brake  9 , and a power input shaft  10  are shown.  FIG. 1B  is a partial top view of the entrance  3 .  FIG. 1C  is a partial top view of the inlet  7 . 
         FIG. 2  is a schematic view showing the present invention in the speed-adjustable unit in operation, 
         FIG. 3A  is cross-sectional view showing the present invention in a speed-collecting Unit.  FIG. 3B  is a partial top view of the exit  4 .  FIG. 3C  is a partial top view of the inlet  7 . 
         FIG. 4  is a schematic view showing the present invention in the speed-adjustable unit in operation; in the figure, a low pressure reservoir  11 , a hydraulic controlling valve block  12 , a speed sensor  13 , a high pressure reservoir  14 , and a pressure sensor  15  are shown. 
     
    
    
     DETAILED DESCRIPTION 
     The following description sets forth exemplary methods, parameters and the like. It should be recognized, however, that such description is not intended as a limitation on the scope of the present disclosure but is instead provided as a description of exemplary embodiments. 
     Referring to  FIG. 1 , an output shaft of a planet differential gear train pump ( 6 ) coaxially couples with a power output shaft ( 1 ) of a hydraulic pump ( 2 ) of through shaft. A bolt ( 5 ) is adopted for fastening said two shafts; thereby, these two shafts contribute to a speed-adjustable unit for a hydraulic mechanism with a power-split system. Herein, the hydraulic variable pump (motor) ( 2 ), a power input shaft, and the power output shaft ( 1 ) are coaxially disposed. The power input shaft ( 10 ) adopts any one of a sun gear, a planet carrier, or a ring gear mainly included in the planet differential gear train pump ( 6 ). Any one of the other two elements of said gears and carrier is coaxially coupled to the power output shaft ( 1 ) and the variable hydraulic pump (motor) ( 2 ). Wherein, the referred coupling includes six variations in turn. The sun gear, the planet carrier, and the ring gear of the planet differential gear train pump ( 6 ) are not fixed to a pump housing, so an output torque of the planet differential gear train pump ( 6 ) equals an input torque thereof. The planet differential gear train pump ( 6 ) allows a mechanical torque of the power input shaft ( 10 ) to be transmitted to the power output shaft ( 1 ) and allows partial mechanical energy to be transformed into static energy of hydraulic fluid. Afterward, the static energy of hydraulic fluid is thence conveyed to the hydraulic variable pump (motor) ( 2 ) and transformed by the same so as to achieve a rotative mechanical torque and an input torque for further adding to the power output shaft ( 1 ). Herein, the rotative speeds of the power output shaft ( 1 ) and the power input shaft ( 10 ) determine an output amount of the hydraulic pressure of the planet differential gear train pump ( 6 ). Namely, the larger the rotative speed difference, the more the output amount. Also, when the discharge amount of the hydraulic variable pump ( 2 ) is increased, the output torque is accordingly augmented. When the output amount of the hydraulic pressure of the planet differential gear train pump ( 6 ) is augmented, the rotative speed of the power output shaft ( 1 ) is lessened. 
     Referring to  FIG. 3 , the input shaft of the planet differential gear train pump ( 6 ) and the power output shaft of the hydraulic variable pump ( 2 ) are coaxially disposed. Wherein, afore two shafts are fastened via the bolt ( 5 ). Accordingly, the shafts further contribute to a speed-collecting unit for the hydraulic mechanism with a power-split energy recovery system. 
     Referring to  FIG. 4 , the speed-adjustable unit for the hydraulic mechanism with the power-split system comprises a friction brake ( 9 ), whose stationary part is fixed to the pump housing and whose moving part is fixed to the power input shaft ( 10 ). The entrance ( 3 ), the exit ( 4 ), two inlets ( 7 ) of the planet differential gear train pump, two outlets ( 8 ) of the planet differential gear train pump, a low pressure reservoir ( 11 ), and a high pressure reservoir ( 14 ) are all attached to a hydraulic controlling valve block ( 12 ). A pressure sensor ( 15 ) is connected to a first passage and a second passage of the high pressure reservoir ( 14 ) for detecting the pressure thereon. A speed sensor ( 13 ) is connected to the power output shaft ( 1 ) for detecting the rotative speed thereon. When the speed of the car or the like transportation is to be reduced, the friction brake ( 9 ) is provided for compactly stopping. Hereby, the low pressure reservoir ( 11 ) connects to the inlets of the planet differential gear train pump ( 6 ) and the variable hydraulic pump (motor) ( 2 ) via the hydraulic controlling valve block ( 12 ). At the same time, the high pressure reservoir ( 14 ) connects to the outlets of the planet differential gear train pump ( 6 ) and the variable hydraulic pump (motor) ( 2 ) via the hydraulic controlling valve block ( 12 ). Accordingly, the planet differential gear train pump ( 6 ) and the variable hydraulic pump of through shaft ( 2 ) are operated in a pumping status since hydraulic oil in the low pressure reservoir ( 11 ) is pumped into the high pressure reservoir ( 14 ), and loaded inertia kinetic energy is recovered and transformed into potential energy of the hydraulic pressure for storing. Correspondingly, while starting the car, the friction brake ( 9 ) is provided for compactly stopping the car. Herein, the high pressure reservoir ( 14 ) connects to the inlet of the planet differential gear train pump ( 6 ) and the entrance of the variable hydraulic pump (motor) ( 2 ) via the hydraulic controlling valve block ( 12 ). Accordingly, the planet differential gear train pump ( 6 ) and the variable hydraulic pump ( 2 ) are operated in a motoring status. Namely, the high pressure reservoir ( 14 ) releasing the hydraulic energy, the hydraulic energy is thus transformed into the mechanical torque and accordingly output via the planet differential gear train pump ( 6 ) and the variable hydraulic pump (motor) ( 2 ). Thereby, the car is propelled via the low pressure reservoir ( 11 ) connecting to the outlet of the planet differential gear train pump ( 6 ) and the exit of the variable hydraulic pump (motor) ( 2 ) through the hydraulic controlling valve block ( 12 ), which concurrently stores the hydraulic oil.