Travel and work functions integrated into a hydraulic hybrid system
A series hydraulic hybrid system for a vehicle is described. The system has a hydraulic circuit, a hydraulic working assembly, and a hydraulic accumulator assembly. The hydraulic circuit has a first hydraulic displacement unit in fluid communication with a second hydraulic displacement unit. The first hydraulic displacement unit is drivingly engaged with a power source. The hydraulic working assembly has a hydraulic implement and a hydraulic working pump in fluid communication with the hydraulic implement, the hydraulic working pump drivingly engaged with the power source. The hydraulic accumulator assembly has a high pressure hydraulic accumulator and a low pressure hydraulic accumulator. The hydraulic accumulator assembly selectively fluidly connects to the hydraulic circuit and the hydraulic accumulator assembly selectively fluidly connects to the hydraulic working assembly.
1. A series hydraulic hybrid system for a vehicle, comprising:
a hydraulic circuit comprising a first hydraulic displacement unit in fluid communication with a second hydraulic displacement unit, the first hydraulic displacement unit drivingly engaged or selectively drivingly engaged with a power source, and the second hydraulic displacement unit drivingly engaged or selectively drivingly engaged with a vehicle output;
a hydraulic working assembly comprising a hydraulic implement and a hydraulic working pump in fluid communication with the hydraulic implement, the hydraulic working pump drivingly engaged or selectively drivingly engaged with the power source; and
a hydraulic accumulator assembly comprising a high pressure hydraulic accumulator and a low pressure hydraulic accumulator, the hydraulic accumulator assembly selectively fluidly connected to the hydraulic circuit and the hydraulic accumulator assembly selectively fluidly connected to the hydraulic working assembly;
at least one high pressure accumulator valve for selectively fluidly connecting the high pressure accumulator to the hydraulic circuit;
at least one low pressure accumulator valve for selectively fluidly connecting the low pressure accumulator to the hydraulic circuit; and
an electronic control unit configured to control the at least one high pressure accumulator valve and the at least one low pressure accumulator valve through electromagnetic signals such that hydraulic fluid may be displaced from the high pressure accumulator to the low pressure accumulator through the second hydraulic displacement unit, thereby driving the second hydraulic displacement unit and the vehicle output drivingly engaged with the second hydraulic displacement unit.
2. The series hydraulic hybrid system of claim 1 ,
wherein the hydraulic circuit comprises a first main fluid line and a second main fluid line, the first main fluid line fluidly connecting or selectively fluidly connecting a first fluid port of the first hydraulic displacement unit to a first fluid port of the second hydraulic displacement unit, and the second main fluid line fluidly connecting or selectively fluidly connecting a second fluid port of the first hydraulic displacement unit to a second fluid port of the second hydraulic displacement unit;
wherein the at least one high pressure accumulator valve is adapted to selectively one of: fluidly disconnect the high pressure hydraulic accumulator from the hydraulic circuit, fluidly connect the high pressure hydraulic accumulator to the first main fluid line while fluidly disconnecting the high pressure accumulator from the second main fluid line, and fluidly connect the high pressure hydraulic accumulator to the second main fluid line while fluidly disconnecting the high pressure accumulator from the first main fluid line; and
wherein the at least one low pressure accumulator valve is adapted to selectively one of: fluidly disconnect the low pressure hydraulic accumulator from the hydraulic circuit, fluidly connect the low pressure hydraulic accumulator to the first main fluid line while fluidly disconnecting the low pressure accumulator from the second main fluid line, and fluidly connect the low pressure hydraulic accumulator to the second main fluid line while fluidly disconnecting the low pressure accumulator from the second main fluid line.
3. The series hydraulic hybrid system of claim 1 , wherein the high pressure hydraulic accumulator is selectively fluidly connected to the hydraulic working assembly, such that the hydraulic working pump is adapted to selectively displace hydraulic fluid from the hydraulic working assembly to the high pressure hydraulic accumulator for pressurizing the high pressure hydraulic accumulator, and such that, when the high pressure hydraulic accumulator is charged, the high pressure hydraulic accumulator is adapted to selectively displace hydraulic fluid from the high pressure hydraulic accumulator to the hydraulic implement for driving the hydraulic implement.
4. The series hydraulic hybrid system of claim 1 , wherein the low pressure hydraulic accumulator is selectively fluidly connected to the hydraulic working assembly, such that the hydraulic working pump is adapted to selectively displace hydraulic fluid from the hydraulic working assembly to the low pressure hydraulic accumulator for pressurizing the low pressure hydraulic accumulator, and such that, when the low pressure hydraulic accumulator is charged, the low pressure hydraulic accumulator is adapted to selectively displace hydraulic fluid from the low pressure hydraulic accumulator to the hydraulic implement for driving the hydraulic implement.
5. The series hydraulic hybrid system of claim 2 , further comprising a mechanical splitter box adapted to selectively drivingly engage a transmission shaft of the first hydraulic displacement unit with a transmission shaft of the hydraulic working pump, such that, when the hydraulic accumulator assembly is charged, the hydraulic accumulator assembly is adapted to selectively drive the hydraulic working pump through the first hydraulic displacement unit by displacing hydraulic fluid from the high pressure hydraulic accumulator to the low pressure hydraulic accumulator through the first hydraulic displacement unit.
6. The series hydraulic hybrid system of claim 1 , wherein the hydraulic circuit comprises a first pair of isolation valves adapted to selectively fluidly disconnect the first hydraulic displacement unit from the second hydraulic displacement unit, and the first pair of isolation valves adapted to selectively fluidly disconnect the first hydraulic displacement unit from the hydraulic accumulator assembly when the hydraulic accumulator assembly is fluidly connected to the hydraulic circuit.
7. The series hydraulic hybrid system of claim 6 , wherein the hydraulic circuit comprises a second pair of isolation valves, the second pair of isolation valves adapted to selectively fluidly disconnect the second hydraulic displacement unit from the first hydraulic displacement unit, and the second pair of isolation valves adapted to selectively fluidly disconnect the second hydraulic displacement unit from the hydraulic accumulator assembly when the hydraulic accumulator assembly is fluidly connected to the hydraulic circuit.
8. The series hydraulic hybrid system of claim 2 , wherein the hydraulic circuit comprises a bypass valve, the bypass valve adapted to selectively fluidly connect the first main fluid line to the second main fluid line.
9. The series hydraulic hybrid system of claim 1 , wherein the second hydraulic displacement unit has a variable hydraulic displacement.
10. A method of operating a series hydraulic hybrid system, the method comprising the steps of:
a) providing the series hydraulic hybrid system comprising:
a hydraulic circuit comprising a first hydraulic displacement unit in fluid communication with a second hydraulic displacement unit, the first hydraulic displacement unit drivingly engaged or selectively drivingly engaged with a power source;
a hydraulic working assembly comprising a hydraulic implement and a hydraulic working pump in fluid communication with the hydraulic implement, the hydraulic working pump drivingly engaged or selectively drivingly engaged with the power source; and
a hydraulic accumulator assembly comprising a high pressure hydraulic accumulator and a low pressure hydraulic accumulator, the hydraulic accumulator assembly selectively fluidly connected to the hydraulic circuit and the hydraulic accumulator assembly selectively fluidly connected to the hydraulic working assembly, wherein the high pressure hydraulic accumulator is selectively fluidly connected to the hydraulic working assembly, such that the hydraulic working pump is adapted to selectively displace hydraulic fluid from the hydraulic working assembly to the high pressure hydraulic accumulator for pressurizing the high pressure hydraulic accumulator, and such that, when the high pressure hydraulic accumulator is charged, the high pressure hydraulic accumulator is adapted to selectively displace hydraulic fluid from the high pressure hydraulic accumulator to the hydraulic implement for driving the hydraulic implement; and
b) one of:
fluidly connecting the high pressure hydraulic accumulator to the hydraulic working pump, and driving the hydraulic working pump to displace hydraulic fluid from the hydraulic working assembly to the high pressure hydraulic accumulator for pressurizing the high pressure hydraulic accumulator; and
fluidly connecting the high pressure hydraulic accumulator to the hydraulic implement, and displacing hydraulic fluid from the high pressure hydraulic accumulator to the hydraulic implement for driving the hydraulic implement.
11. A method of operating a series hydraulic hybrid system, the method comprising the steps of:
a) providing the series hydraulic hybrid system comprising:
a hydraulic circuit comprising a first hydraulic displacement unit in fluid communication with a second hydraulic displacement unit, the first hydraulic displacement unit drivingly engaged or selectively drivingly engaged with a power source;
a hydraulic working assembly comprising a hydraulic implement and a hydraulic working pump in fluid communication with the hydraulic implement, the hydraulic working pump drivingly engaged or selectively drivingly engaged with the power source; and
a hydraulic accumulator assembly comprising a high pressure hydraulic accumulator and a low pressure hydraulic accumulator, the hydraulic accumulator assembly selectively fluidly connected to the hydraulic circuit and the hydraulic accumulator assembly selectively fluidly connected to the hydraulic working assembly, wherein the low pressure hydraulic accumulator is selectively fluidly connected to the hydraulic working assembly, such that the hydraulic working pump is adapted to selectively displace hydraulic fluid from the hydraulic working assembly to the low pressure hydraulic accumulator for pressurizing the low pressure hydraulic accumulator, and such that, when the low pressure hydraulic accumulator is charged, the low pressure hydraulic accumulator is adapted to selectively displace hydraulic fluid from the low pressure hydraulic accumulator to the hydraulic implement for driving the hydraulic implement; and
b) one of:
fluidly connecting the low pressure hydraulic accumulator to the hydraulic working pump, and driving the hydraulic working pump to displace hydraulic fluid from the hydraulic working assembly to the low pressure hydraulic accumulator for pressurizing the low pressure hydraulic accumulator; and
fluidly connecting the low pressure hydraulic accumulator to the hydraulic implement, and displacing hydraulic fluid from the low pressure hydraulic accumulator to the hydraulic implement for driving the hydraulic implement.