Patent Application
20100122864
International classification . . . B60K 3/00; B60K 6/12; B60K 6/02; B60K 6/00; B60K 17/00; B60T 8/64; B62M 1/10; F15B 1/02; F16D 31/02; F04B 49/00; G06F 17/00
U.S. Cl . . . 180/165, 105/96.2, 105/238.1 180/365; 180/307,367,303/152; 60/408, 413, 414,415, 416, 418, 448, 449; 701/69; 903/941
Field of classification search . . . 105/96.2; 180/165, 180/365; 180/305, 306, 307,367,303,152; 280/212, 216; 303/112, 303/152, 303/113, 1, 10, 11, 413, 414, 416, 60/408, 409,413, 414, 416, 418,448,449; 701/69; 903/941
1. Field of the Invention
The present invention relates to a series hybrid hydraulic drive system than can be applied with advantage to all terrestrial vehicles, including Industrial, commercial and military applications and eventually to passenger vehicles. The prime mover is used to its maximum capacity when running, and reloading of the accumulator occurs when braking and/or when the prime mover is running.
2. Description of Prior Art
Hybrid Hydraulic—regenerative-drive systems are known and have been applied to motor vehicles in the past. Parallel hydraulic systems are available and have been successful in getting the braking energy back to the accumulator for future use to accelerate the vehicle with acceptable energy savings.
The parallel hydraulic system is used as an add-on on vehicles and does not solve the full energy consumption issue of those vehicles.
The series hybrid hydraulic system goes beyond the parallel system, but lacks a good and precise flow control-speed-and has not solved, at low cost, the recharge of the accumulator using the extra power of the prime mover when available.
Both solutions have a very large handicap: steel accumulators weigh more than 50 times the weight of a lead-acid battery per unit of stored energy. When fiber made accumulators are used, the weight differential is still 12 to 1, but the price skyrockets. Hence all accumulators used for present hybrid hydraulic applications are quite small and usable only for short cycles, mainly for brake energy recuperation.
This issue does not allow for those systems to stop the engine when the accumulator is full, as the vehicle will only run for several seconds with the energy content of the accumulator. The present hydraulics are not prepared to allow for this operating mode.
The intention of this invention is to overcome the limitations of the prior art by using a simpler and less expensive system, as well being able to dramatically increase the efficiency of all terrestrials vehicles and cut substantially their emissions.
A hybrid hydraulic system whose objective is to change the economic and technical obstacles confronting hydraulics and its use in terrestrial vehicles, adding benefits not available with the prior art.
The use of the accumulator of a hydraulic system as the main chassis of the vehicle overcomes one of the major issues for the implementation of hydraulics, the large weight per unit of stored energy. At the same time this development allows for much larger accumulators, as the accumulator weight is no longer an issue. This new available dimension allows for periods of operation without the prime mover running, saving a large portion of fuel and emissions, as engines and electric motors consume unloaded about 40% of the maximum consumption or current in the case of the electric motors.
When the prime mover is running, it will do so at the maximum torque with the proper rpm, it's most efficient point. If the operation does not need fully this power, the secondary pump will be reloading the accumulator with that available energy. The hydraulic motors will do the same when braking. The prime mover then, when running, will do so only at its optimum efficiency almost all the time.
When more torque is needed at the wheels, mainly for acceleration, the accumulator flow will open to the inlet of the power integrator, helping the prime mover to accelerate the vehicle. Of course, the consequence of this arrangement enables the use of smaller prime movers for the same weight and acceleration vehicles. If the pressure coming from the accumulator is too high, the secondary pump will then send the extra energy from the prime mover back to the accumulator. In some cases, we could have several settings for the speed of the prime mover: let's say urban traffic (low), freeway (middle) and mountain (faster).
The coordination of the operation of the system is done with computer and copyrighted software. One version of the controls allows for the use of one pedal or joystick to control speed, direction, acceleration and braking and with a joystick one can add steering, for a vehicle much simpler to control and much safer to operate. The infinite automatic transmission allows for an even better efficiency and lower emissions.
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The preferred embodiment of the present invention is contained in
The prime mover 10 is connected via a unidirectional coupling 26 to a special unidirectional variable power integrator 11 and in the same shaft, to a unidirectional variable flow pump 12. This unidirectional coupling is required to allow for the operation of the system when the prime mover is not running. Pump 11 is controlled by servo valve 9 and pump 12 is controlled by servo valve 8. Both servo valves receive the proper signals from the controller 27. The accumulator 2 has an electronic oil level indicator that signals the amount of oil in the accumulator 2 to the controller 27. If the amount of oil is large, the signal to start the system will not launch the prime mover 10. If the signal indicates a low amount of oil in the accumulator 2, the prime mover will automatically be started.
Once the prime mover 10 is running, power integrator 11 and pump 12 will have zero flow initially. Pump 12 will flow immediately after, charging the accumulator with the available torque from prime mover 10, via check valve 6, taking oil from tank 16. Pump 11, once it receives a signal to go to a certain flow, will take oil from tank 16, via check valve 17 and send oil to the hydraulic motors 14(and 15 if so built) via flowmeter 35, check valve 40, solenoid valve 13(only one version shown) and controlling block 18. The block 18 will have functions like relief valves, differential control effects, flow sharing, etc. The flow will be the same independent of the pressure. There are two anticavitation valves 19 than could be part of block 18 that go to tank 16. Pilot line 41 goes to a pilot operated three way, two position valve 4. When the pressure on line 41 reaches a certain value, valve 4 will open the output of the hydraulic motors to tank 16. On a generating mode, valve 4 sends the output flow of the motors 14 (and motors 15) via check valve 25 and valve 42 to the accumulator 2. If the accumulator 2 reaches a certain pressure, oil is discharged back to tank via relief valve 7 or to the inlet of the pump 11. Valve 42 is just a service valve that isolates the accumulator for safety purposes. The safety and/or auxiliary brakes are not represented here,
If the output pressure of pump 11 reaches a certain threshold, a pilot line goes thru solenoid valve 36 (two way, two position) to pilot valve 20—three way, two position valve. The output of valve 20 goes through solenoid valve 33—three way, two position valve—and controlled orifice 39 to pilot open check valve 5. This action connects the high pressure accumulator to the inlet of power integrator 11, to allow for an elevated pressure at the output, obtaining higher accelerations of the vehicle with a much smaller engine. The accumulator flow is the main output flow of power integrator 11 and is controlled but said device 11. Any over speed of the prime mover—known via speed sensor 31—makes pump 12 send the extra energy back to the accumulator and in so doing, controlling over speed.
When the prime mover is not running because enough energy is stored in the accumulator, we will describe the new running mode: Solenoid valve 36 is energized, closing the pilot line to the pilot operated valve 20. Solenoid valve 33—three way, two position valve—is energized opening the accumulator 2 via check valve 5, to the inlet of power integrator 11. The speed of the vehicle—meaning the output flow of power integrator 11—will be controlled by the swash plate position of said power integrator 11 and same for pump 12.
Pedal 29 or Joystick 34, command a position sensor 30 that signals to the controller what speed is the one desired, and what acceleration or braking rate is required. Internal controls limit both the acceleration and braking or deceleration rate to a given maximum. Switch 38 is a one-off switch to allow for reverse operation when needed. Both the pedal 29 and Joystick 34 go to zero output when released. If, at that point, prime mover 10 is running, it will continue running only until the accumulator 2 is full, loading it via pump 12 and servo control 8. In that condition, power integrator 11 is not creating any output flow; hence the vehicle is at a standstill. If the Joystick 34 is supplied with an auxiliary position sensor for lateral movement, then we have a Joystick able to additionally control steering. This is not applicable to vehicles running on rails, but all the other functions are. Several pressure transducers 32 allow for the controller to know the instantaneous pressure in several part of the hydraulic circuit, and react properly for the operation and safety of the vehicle.
Some auxiliary hydraulic functions could be described here. Charge pump 23 is a low flow, low pressure pump powered by small electric motor 22. Charge pump 23 could also be powered by main shaft of prime mover, mounted after pump 12. Suction filter 24, coming from tank 16, gets the flow to the inlet of pump 23, output of pump 23, goes to filter 18, relief valve 21, cooler 20, back to tank 16.
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