US3609964A - Regulated hydraulic drive - Google Patents

Regulated hydraulic drive Download PDF

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Publication number
US3609964A
US3609964A US28424A US3609964DA US3609964A US 3609964 A US3609964 A US 3609964A US 28424 A US28424 A US 28424A US 3609964D A US3609964D A US 3609964DA US 3609964 A US3609964 A US 3609964A
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United States
Prior art keywords
throttle
pressure
pump
transmission
hydraulic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US28424A
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English (en)
Inventor
Walter Kobald
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Robert Bosch GmbH
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Robert Bosch GmbH
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Filing date
Publication date
Priority claimed from DE19691920859 external-priority patent/DE1920859C3/de
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
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Publication of US3609964A publication Critical patent/US3609964A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K17/00—Arrangement or mounting of transmissions in vehicles
    • B60K17/04—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location or kind of gearing
    • B60K17/10—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location or kind of gearing of fluid gearing

Definitions

  • a hydraulic drive comprises a combustion engine, a hydraulic transmission whose pump is driven by the engine, and a regulating apparatus including an auxiliary pump discharging through a main conduit, whose pressure is regulated by a pressure-regulating valve under the control of an operator, and through two variable throttles whose throttle cross-sections are simultaneously increased and decreased, respectively, by throttle control means responsive to the pressure in the transmission pump.
  • the different throttled pressures are applied to a first servo motor controlling the rotary speed of the combustion engine, and to a second servo motor controlling the transmission pump to vary the piston stroke and output of the same.
  • the transmission motor operates at different rotary speeds, and any selected rotary speed is maintained by the regulating apparatus constant and independent of the load, while the regulated hydraulic drive operates at optimal efliciency.
  • German Pat. 1,204,569 discloses a regulated hydraulic drive with a regulating apparatus which is, on the one hand controlled by the foot pedal determining the rotary speed of the prime mover combustion engine, and, on the other hand, is controlled by the pressure prevailing in the hydrostatic transmissionwhose pump is driven by the combustion engine.
  • the apparatus of the prior art permits it to operate the combustion engine and the hydrostatic transmission in a range of high efficiency.
  • a great number of regulating devices and control valves are necessary, so that the hydraulic drive of the prior art is very expensive.
  • centrifugal governors are used for regulation which are unreliable in the lower speed range.
  • pressure medium under constant pressure which is divided into two branch streams respectively fiowing through first and second throttles.
  • the first throttles are of equal and constant throttle cross-section, while the second throttles have throttle cross-sections which are variable and are simultaneously varied by control means responsive to the pressure in the hydrostatic transmission.
  • One of the branch streams controls the supply of fuel to the combustion engine, and the other controls the stroke of the transmission pump.
  • a regulating apparatus includes a source of pressure medium, such as an auxiliary pump, conduit means including a main conduit receiving the medium from the source and first and second branch conduits, first hydraulic operating means communicating with the first branch conduit and operatively connected with the first control means for operating the same, second hydraulic operating means communicating with the second branch conduit and operatively connected with the second control means for operating the same, a first throttle means communicating with the first branch conduit, a second throttle means communicating with the second branch conduit, a throttle control means for varying the throttle cross-sections of the first and second throttle means, and throttle operating means operatively connected with the throttle control means and hydraulically connected with the hydrostatic transmission for operating the throttle control means in response to the pressure in the hydrostatic transmission.
  • a source of pressure medium such as an auxiliary pump
  • conduit means including a main conduit receiving the medium from the source and first and second branch conduits, first hydraulic operating means communicating with the first branch conduit and operatively connected with the first control means for operating the same, second hydraulic operating means communicating with the second branch conduit and operatively connected with the
  • Operator-controlled means preferably including a pressure-regulating valve in the main conduit, are provided for producing selected pressures in the main conduit so that in every position of the operator-controlled means, a different rotary speed is maintained constant and independent of the load variations of the hydraulic motor, while the engine and hydraulic transmission operate at optimal efiiciency.
  • FIG. 1 is a schematic view illustrating a regulated by draulic drive according to the invention
  • FIG. 2 is a fragmentary schematic view illustrating a regulating apparatus used in the drive of FIG. 1;
  • FIG. 3 is a fragmentary schematic view illustrating a modified throttle control means
  • FIG. 4 is a diagram graphically illustrating speed variations of the prime mover engine over the ratio of the hydrostatic transmission.
  • a diesel motor 1 serves as prime mover and has a first control means 2 which can be adjusted to vary the speed of the output shaft of the combustion engine 1 which is schematically indicated by the number of revolutions n of the output shaft of the combustion engine 1.
  • the output shaft is connected with the input shaft of a hydraulic pump 3 which consequently also rotates at the rotary speed in.
  • Hydraulic pump 3 which is preferably an axial piston pump with a Wobble plate, drives a corresponding hydraulic motor 4 whose output shaft has n revolutions.
  • the Wheels of the vehicle, not shown, are driven by hydraulic motor 4 at n revolutions per minute.
  • a regulating apparatus which is illustrated in detail in FIG.
  • the regulating ap- 3 paratus is connected with the first control means) O f 'thecor'nbu's'tion en'gine'l for" varying the rotary speed In and also connected with second control means 7 for varying the length of the piston stroke and the output of the pump 3 which drives hydraulic motor 4 accordingly.
  • FIG. 2 which illustrates schematical ly the regulating apparatus 5
  • an auxiliary pump 8 is provided as part of the regulating apparatus, and pumps a pressure medium into a main conduit 9, 12 which is connected with a conduit 10 in which a pressure regulating valve 11 is located which is controlled by the foot pedal 6, or other adjusting means controlled by the driver of 'the vehicle.
  • Auxiliary pump 8 pumps the pressure medium 'out of container means 35 into which also conduit 10 discharges,
  • the pressure medium flows from main conduit 12 into two branch conduits 13 and 13" in which throttles 14 and 14 are provided which have the same throttle cross-section F.
  • Branch conduit 13 communicates with a conduit 20 leading to a first hydraulic operating means shown to be a servo motor having a cylinder 21, a piston 23, and a spring 22 urging piston 23 -to oppose the pressure medium'flowing from conduit 20 into cylinder 21.
  • Piston 23 is mechanically connected with the first control means 2, see FIG. 1, by which the speed "inder 16.
  • Piston 18 is connected with second control means 7 by which the stroke of I output, is adjusted.
  • conduit 20 remote from cylinder 21 is pump 3, and thereby its shown in axial section, and has a throttle opening 24.
  • the end of conduit remote from cylinder 16 is shown -'in axial section and has a throttle opening '19confronting throttle opening 24 and being aligned with the same.
  • a throttle control member 25 has a central cylindrical portion guided in a guideway 26 for longitudinal movement, and has two conical end portions 27 and 28 WhlCh respectively project into throttle openings 24 and 19, forming annular throttle cross-sections F and F in i the same.
  • throttle control member 25 i displaced in guideway 26 into throttle opening 24, the'thro'ttle crosssection F is decreased, and the throttle cross-section F is increased.
  • throttle cross-section F is decreased, and" throttle cross-section F is increased so that the two throttles are always simultaneously operated and adjusted.
  • An arm 30 passes through a cut-out in the guideway 26 to throttle control member 25. Arm 30 is fixedly secured .snthat th.. .il11:9 .1 openin s 2.4 and 12ers, heat d. in?
  • a throttle control member 36 has the form of a non-circular plate whose peripheral edge crosses throttle openings 24 and 19, reducing the free throttle cross-sections F and F Throttle-co n'tr'ol member 36 is turned about a shaft 38 by'throttle-operating means including a cylinder 37, corresponding to cylinder 33 a piston 37a connected with throttle-control member 36.
  • the pressure medium is supplied throughconduits 35'. frornth pump 3 into cylinder 37.
  • throttle-control member 36 is turned to increase the free flow cross-section F when the free flow cross-section F is reduced, and vice versa.
  • the operator or driver of a vehicle displaces the adjusting means 6, suchas' a foot pedal, so that the pressureregulating'valve 11 determines apressure p in conduit 12 on which the speed of the vehicle depends whose wheels are driven by'the hydraulic motor' 4.
  • the displacement of the foot pedal 6 is proportional to the vehicle speed V and to the number of revolutions n of hydraulic ,motor 4. For each position of the foot pedal, a different constant pressure p and a different number of revolut ions n is obtained.
  • the regulating apparatus of FIG. 2 must also assure that, while optimal elficiency is maintained, the selected vehicle speed V remains constant even if the vehicle encounters resistance, and the .load on the hydraulic motor 4 ,varies. This can be'obtained when the regulating graph has the shape .of a hyperbola. I I t As shown in FIG.
  • the-abscissa represents the transmission ratio i of the hydrostatic transmission 3, 4, and the ordinate represents the number of revolutions n; of the combustion engine 1, and of the pump 3.
  • Each position s of the foot pedal 6 is associatedwith a dilfei'ent hyperbolic regulating graph some of which are shown in FIG. 4.
  • the regulation is obtained in the following manner
  • the conduits 15 and 20' are connected with the branch conduits 13 and 13 as explained above for conduits 20 and 15, but are paralleltransmissiompumps a pressure mediuminto. the main conduit 9,. 10, 12. .
  • the pressure medium inconduit 12 flows into the two branch conduits 13 and 13-",- and each of the branch streams'of the pressure medium 'fiowsthrough .the identical throttles 14, 14 having the throttle crosssection F, so that the pressure'of therespective branch streams p and p are accordingly reduced.
  • the pressure medium in .branch conduit 13 flows through conduit 20 and through the free throttle crosssection F into the container 35, and the same is .the'case with the pressure medium in branch conduit13 which flows through the free throttle cross-'sectionF intoxcontainer 35.
  • the throttle cross-sectionsF and F are increased or reduced, depending on the position-of throttle control member25 which is displaced in accordance with the pressure in the throttle-operating means'32, 33' to which pressure fluid is supplied at a pressure pi frornthe hydrostatic transmissiom-A pressure p is produced in branch conduit 13, and thepressure p' is'produ'cedrin branch conduit 13'.
  • Pressure p acts on servo motor 21, 22, 23 so that piston 23 operates the control means 2 of combustion engine 1, influencing the number of revolutions it, of the output shaft of combustion engine 1, and of the input shaft of pump 3.
  • the pressure p acts in the cylinder 16 of the servo motor 16, 17, 18 so that piston 18 is displaced accordingly, and adjusts control means 7 by which the piston stroke of the pump 3 is adjusted, for example by tilting the Wobble plate of an axial piston pump.
  • the pressure p of the fluid circulating in the hydrostatic transmission is supplied to the cylinder 33 of the throttle-operating servo motor 32, 33, 34.
  • the pressure p is proportional to the number of revolutions and to the rotaryspeed n of the combustion engine and of pump 3, while the pressure p is proportional to the transmission ratio i of the hydrostatic transmission 3, 4.
  • the speed V of the vehicle driven by hydraulic motor 4 is proportional to the product of the number of revolutions of combustion engine 11 and the transmission ratio i of the hydrostatic transmission 3, 4. It follows that V is proportional to p -p This means that for a selected speed of the vehicle, which should be constant, and in the event of variations of the pressure p and p during regulation, the system of coordinates shown in FIG. 4 will show a hyperbolic graph.
  • F F i- 1 35+ 1 which represents a hyperbola with p and p as variables while K is a constant factor.
  • the vehicle speed V varies with the pressure 12;; which is obtained by displacing foot pedal 6 and adjusting pressure-regulating valve 11.
  • F is the throttle cross-section of throttles 14 and 14
  • F is the annular throttle cross-section of throttle 24, 27, and
  • F is the throttle cross-section of throttle 19,28.
  • the peripheral shape of the throttle control member 36 is selected so that the throttle cross-sections F and F are determined in accordance with the required'mathematical conditions.
  • the throttle control member 25 has conical end portions slanted at different angles for obtaining the required relationship between the throttle cross-sections F and F
  • the pressure p and p depend on the free area of the throttle cross-sections.
  • conduits are shown in FIG. 2 in a schematic manner, and it will be understood that the conduits can be constructed as channels and bores in the walls of a regulator casing, in which the throttles and the pressure-regulating valve 11 are provided.
  • hydraulic motor 4 cannot be adjusted. If hydraulic motor 4 is adjustable, and has a tiltable wobble plate, for example, a hydraulic servo motor operating the wobble plate is hydraulically connected with the main conduit 12 in which a constant selected pressure prevails.
  • Regulated hydraulic drive comprising a prime mover engine having first control means for varying the speed of said engine; a hydrostatic transmission including a hydraulic pump driven by said engine, and a hydraulic motor driven by said pump, said transmission having second control means for varying the output of said pump whereby the speed of said hydraulic motor is varied; a regulating apparatus including a source of a pressure medium, conduit means including a main conduit receiving said medium from said source and first and second branch conduits.
  • first hydraulic operating means communicating with said rfirst branch conduit and operatively connected with said first control means for operating the same
  • second hydraulic operating means communicating with said second branch conduit and operatively connected with said second control means for operating the same
  • a first throttle means communicating with said first branch conduit
  • 21 second throttle means communicating with said second branch conduit
  • a throttle control means for varying the throttle cross-section of said first and second throttle means
  • throttle operating means operatively connected with said throttle control means and hydraulically connect-' ed with said hydrostatic transmission for operating said throttle control means in response to the pressure in said hydrostatic transmission whereby the pressure in saidifirst' and second branch conduits are proportional to the speed of said engine and to theratio of said transmission, respectively
  • operator controlled means in said maincon duit for producing selected pressures in said main conduit so that in every position of said operator controlled means a diiferent rotary speed of said hydraulic motor is maintained constant and independent of the load variations of said hydraulic motor while said engine andhydraulic transmission operate at optimal efiiciency.
  • first and second hydraulic operating means include first and second hydraulic servo motors, respectively, said first servo motor including a first cylinder communicating with said first branch conduit and a first piston connected with said first control means, and said second servo motor including a second cylinder communicating with said second branch conduit and a second piston connected with said second control means.
  • said operator controlled means includes a pressure-regulating valve communicating with said main conduit, and an adjusting meahs adapted to be operated by an operator for setting said pressure-regulating valve to maintain a selected pressure in said main conduit.
  • Regulated hydraulic drive as claimed in claim 12 wherein said pump is, a rotary piston pump; wherein said second control means adjusts the length of the piston stroke of said pump; wherein said throttle operating means is hydraulically connected with said pump and responds to the pressure in the same; and wherein said throttle control means include a throttle control member increasing the throttling cross section of said first throttle means when decreasing the throttling cross section of said second throttle means, and vice versa.
  • said operator controlled means includes a pressure-regulating valve communicating with said main conduit, and an adjusting means adapted to be operated'by an operator for setting said pressure-regulating valve to maintain a selected pressure in said main conduit means; wherein said regulating apparatus includes first and second throttles having the same throttling cross-section and connecting said main conduit with said first and second branch conduits, respectively; wherein said engine is a combustion engine; wherein said first control means controls the admission of a fuel mixture into said com-' bustion engine; wherein said pump is a pistonpump;
  • said second control means adjusts the length responds to the pressure in the same; wherein said source of pressure medium is an auxiliary pump; wherein said first and second throttle means have outlets for discharging said pressure medium; wherein said throttle con trol means include a throttle control member increasing the throttling cross section of said first throttle means when decreasing the throttling cross section of said second throttle means, and vice versa; and wherein said first and second hydraulic operating means include first and second hydraulic servo motors, respectively, said first servo motor including a first cylinder communicating with said first branch conduit and a first piston connected with said first control means, and said second servo motor including a second cylinder communicating with said second branch conduit and a second piston connected with said second control means.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Fluid Gearings (AREA)
  • Control Of Transmission Device (AREA)
  • Control Of Driving Devices And Active Controlling Of Vehicle (AREA)
  • Fluid-Pressure Circuits (AREA)
US28424A 1969-04-24 1970-04-14 Regulated hydraulic drive Expired - Lifetime US3609964A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19691920859 DE1920859C3 (de) 1969-04-24 Regelvorrichtung für ein hydrostatisches Getriebe und die dieses antreibende Brennkraftmaschine für Fahrzeuge

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US3609964A true US3609964A (en) 1971-10-05

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US28424A Expired - Lifetime US3609964A (en) 1969-04-24 1970-04-14 Regulated hydraulic drive

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US (1) US3609964A (de)
JP (1) JPS4936297B1 (de)
CH (1) CH508498A (de)
FR (1) FR2039090A5 (de)
GB (1) GB1312004A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3841795A (en) * 1972-07-17 1974-10-15 Caterpillar Tractor Co Combined engine speed and pressure responsive control for variable displacement pumps
US3937597A (en) * 1973-10-03 1976-02-10 Poclain Pressurized fluid feed apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3841795A (en) * 1972-07-17 1974-10-15 Caterpillar Tractor Co Combined engine speed and pressure responsive control for variable displacement pumps
US3937597A (en) * 1973-10-03 1976-02-10 Poclain Pressurized fluid feed apparatus

Also Published As

Publication number Publication date
DE1920859B2 (de) 1976-04-15
JPS4936297B1 (de) 1974-09-28
CH508498A (de) 1971-06-15
FR2039090A5 (de) 1971-01-08
GB1312004A (en) 1973-04-04
DE1920859A1 (de) 1970-11-12

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