US20130202452A1 - Hydraulic fan drive - Google Patents

Hydraulic fan drive Download PDF

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Publication number
US20130202452A1
US20130202452A1 US13/638,016 US201113638016A US2013202452A1 US 20130202452 A1 US20130202452 A1 US 20130202452A1 US 201113638016 A US201113638016 A US 201113638016A US 2013202452 A1 US2013202452 A1 US 2013202452A1
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Prior art keywords
pressure
hydraulic
hydraulic motor
port
control
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US13/638,016
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English (en)
Inventor
Michael Schuette
Tobias Pfruender
Martin Fassbender
Egon Rill
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Robert Bosch GmbH
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Robert Bosch GmbH
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Assigned to ROBERT BOSCH GMBH reassignment ROBERT BOSCH GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: FASSBENDER, MARTIN, SCHUETTE, MICHAEL, RILL, EGON, PFRUENDER, TOBIAS
Publication of US20130202452A1 publication Critical patent/US20130202452A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D13/00—Pumping installations or systems
    • F04D13/02—Units comprising pumps and their driving means
    • F04D13/04—Units comprising pumps and their driving means the pump being fluid driven
    • F04D13/046—Units comprising pumps and their driving means the pump being fluid driven the fluid driving means being a hydraulic motor of the positive displacement type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P7/00—Controlling of coolant flow
    • F01P7/02—Controlling of coolant flow the coolant being cooling-air
    • F01P7/04—Controlling of coolant flow the coolant being cooling-air by varying pump speed, e.g. by changing pump-drive gear ratio
    • F01P7/044—Controlling of coolant flow the coolant being cooling-air by varying pump speed, e.g. by changing pump-drive gear ratio using hydraulic drives

Definitions

  • the invention starts from a hydraulic fan drive, which has a hydraulic pump of adjustable swept volume, which is assigned a pressure control valve arrangement for regulating a pump pressure by adjustment of the swept volume, a hydraulic motor for driving a fan impeller, and a pressure line, which is connected to a pressure inlet of the hydraulic motor and into which pressure medium can be delivered by the hydraulic pump.
  • Fan drives of this kind can be used especially in construction machines, agricultural and forestry machines, in conveying applications, in trucks and buses and in rail vehicles.
  • a fan drive of this kind is known from DE 43 21 637 A1, for example.
  • the pressure-regulated hydraulic pump is operated with a hydraulic motor of constant displacement in an open hydraulic circuit.
  • the pressure control valve arrangement consists essentially of a control valve having a pressure port, which is connected to the pressure outlet of the hydraulic pump and at which therefore the pump pressure is available, a tank port connected to a tank, and a control port connected to the adjusting chamber at an adjusting piston, of a directly controlled pressure limiting valve that can be adjusted by electroproportional means, and of a nozzle, which is arranged between the pressure outlet of the hydraulic pump and the inlet of the pressure limiting valve.
  • the control piston of the control valve is acted upon by the pump pressure so as to produce a fluidic connection of the pressure outlet of the hydraulic pump and so as to reduce the swept volume (delivery volume per revolution) of the hydraulic pump with the control port and is acted upon by a spring and by the pressure prevailing at the inlet of the pressure limiting valve so as to produce a fluidic connection of the control port to the tank port and so as to increase the displacement.
  • a particular setting of the pressure limiting valve thus gives a particular pump pressure and therefore a particular torque at the hydraulic motor and hence a particular speed of the fan impeller.
  • this object is achieved by virtue of the fact that, in the hydraulic fan drive having the features from the preamble of patent claim 1, a hydraulic accumulator is connected to the pressure line, and the hydraulic motor has an adjustable displacement.
  • connecting the hydraulic accumulator to the pressure line makes it possible to buffer-store energy by feeding in pressure medium beyond the amount which is displaced by the hydraulic motor, this energy being released in other operations on the machine, for example during a braking operation or during the lowering of a load.
  • the pressure changes in the pressure line which are associated with the buffer storage and the output of energy can be compensated for in such a way by a change in the displacement of the hydraulic motor that the torque which is output by the hydraulic motor corresponds to the desired fan speed.
  • the hydraulic accumulator is preferably connected directly to the pressure line without valves, which require actuation.
  • Additional energy can be fed in directly by the hydraulic pump, for example, if, in accordance with patent claim 2 , the setting of the pressure control valve arrangement can be varied by remote control. In normal operation, it is advantageous if the pressure control valve arrangement is set to a pressure which lies midway between the maximum and the minimum accumulator operating pressure. If the pressure control valve arrangement is then set to a higher pressure, additional pressure medium can be fed into the hydraulic accumulator in the event of a braking operation or a sudden relief of the load on a diesel engine driving the hydraulic pump, for example, in order to provide a speed safety feature for said engine. The increased pressure level is compensated for by a reduction in the displacement of the hydraulic motor, ensuring that there is no change in the fan speed.
  • a check valve which closes toward the hydraulic pump, is arranged between the hydraulic pump and a section of the pressure line to which the hydraulic accumulator is connected, pressure medium can be fed into the pressure line independently of the hydraulic pump and independently of the pressure setting thereof to a higher pressure level.
  • the buffer-stored energy can be used to drive the hydraulic motor and, where there is a check valve at the pump outlet, an adjustable pressure control valve arrangement can be set to the original value again immediately after the feeding in of an additional volume of pressure medium. Without a check valve, it may be advantageous if the pressure control valve arrangement is in each case set to a somewhat higher pressure than the instantaneous accumulator pressure. This can also be achieved by means of a slow time-dependent withdrawal of the control signal for the pressure control valve arrangement.
  • the hydraulic pump can also be operated as a hydraulic motor while retaining the direction of rotation.
  • this is already possible with the aid of a directional control valve, by means of which the high-pressure port and the low-pressure port of the hydraulic pump can be interchanged.
  • the pump is a hydraulic pump that can be adjusted via zero, and it can therefore also be operated as a hydraulic motor with the same pressure port and the same direction of rotation.
  • the power output by the diesel engine can be smoothed out or held constant.
  • the pressure control valve arrangement can also be set to values below the normal pressure level, thus making available a particularly large amount of energy to support the diesel engine or, more generally, an internal combustion engine or even an electric motor (primary unit).
  • the hydraulic motor can even be set to a displacement of zero so that, although the fan impeller is not driven for a brief period, all the energy stored is available to support the primary unit.
  • the primary unit is subject to less stress by virtue of more uniform loading and, as a result, has a more advantageous consumption of primary energy.
  • the hydraulic motor is assigned a torque control valve arrangement for regulating a motor torque by adjusting the displacement. Given a particular control signal, the hydraulic motor is then in each case set to the displacement which gives the torque corresponding to the desired speed of the fan impeller at the pressure currently prevailing in the pressure line and in the hydraulic accumulator. This is automatically compensated in the case of pressure fluctuations. By changing a hydraulic control pressure or an electric control signal, the torque characteristic can be shifted in parallel. A particularly simple parallel arrangement of a plurality of torque-regulated fan motors to drive a plurality of fan impellers is also possible.
  • the torque control valve arrangement is preferably designed in accordance with patent claim 9 .
  • the hydraulic motor can also be assigned a control valve arrangement, by means of which the displacement of the hydraulic motor can be varied proportionally to a control signal, wherein the control signal is dependent, on the one hand, on a setpoint speed value of the hydraulic motor and, on the other hand, on a detected speed of the hydraulic motor or on the detected pressure in the pressure line. From the detected speed, it is possible to ascertain directly, by comparison with the setpoint speed, whether the displacement has to be increased or reduced. From the detected pressure and the setpoint speed, the setpoint displacement can be calculated and specified.
  • FIG. 1 shows the first illustrative embodiment, in which the hydraulic pump has a remote controllable pressure control valve arrangement for varying the pressure level in a hydraulic accumulator and has a swept volume that can be adjusted via zero,
  • FIG. 2 shows the second illustrative embodiment, in which the hydraulic pump has a pressure control valve arrangement set to a fixed value and the pressure level in the hydraulic accumulator can be raised by means of an external pressure medium source and the hydraulic motor is torque-controlled, and
  • FIG. 3 shows the third illustrative embodiment, in which, as in the first illustrative embodiment, the hydraulic pump has a remote controllable pressure control valve arrangement for varying the pressure level in a hydraulic accumulator and has a swept volume that can be adjusted via zero and in which, as in the second illustrative embodiment, the hydraulic motor is torque-controlled.
  • the hydraulic fan drive comprises a first hydraulic machine 10 , which is so called because it can be operated both as a hydraulic pump and as a hydraulic motor.
  • the hydraulic machine 10 is connected mechanically to a diesel engine 11 . It has a high-pressure port (pressure port) 12 and a low-pressure port (tank port) 13 , which is continuously connected to a tank 9 .
  • a pressure line 14 leads to a hydraulic motor 15 , by which a fan impeller 16 can be driven.
  • a hydraulic accumulator 17 Connected directly to the pressure line is a hydraulic accumulator 17 , which can be operated in a pressure range of between 100 bar and 300 bar, for example, and is charged to 200 bar in normal operation.
  • the hydraulic machine is, for example, an axial piston machine of swashplate construction, the swept volume of which can be adjusted via zero between a maximum positive value and a maximum negative value.
  • the hydraulic machine 10 delivers pressure medium into the pressure line 14 as a hydraulic pump.
  • the hydraulic machine operates as a hydraulic motor in the same direction of rotation and is supplied with pressure medium from the pressure line 14 .
  • adjusting piston 18 For adjustment of the swept volume, there are two adjusting pistons and a spring, of which one adjusting piston 18 , which has a larger effective area than the other adjusting piston, delimits an adjusting chamber 19 , to which pressure medium can be fed and from which pressure medium can be released.
  • This feeding and discharge of pressure medium is controlled by a pressure control valve arrangement 20 mounted on the hydraulic machine 10 .
  • This arrangement includes a continuously adjustable control valve 21 with a zero overlap or a small positive overlap between the control edges and with a pressure port 22 , which is connected fluidically to the pressure port 12 of the hydraulic machine 10 , a tank port 23 , which is connected to a leakage oil port 30 via the interior of the housing of the hydraulic machine 10 , and a control port 24 , which is connected via a damping nozzle 25 to the adjusting chamber 19 .
  • the valve piston of the control valve is acted upon by the pump pressure so as to connect the control port 24 to the pressure port 22 and so as to reduce the swept volume of the hydraulic machine 12 as far as negative values and by a spring 26 and a variable control pressure so as to connect the control port 24 to the tank port 23 and so as to increase the swept volume, said control pressure being picked off between a control oil nozzle 27 and a pressure limiting valve 28 that can be adjusted proportionally by an electromagnet 29 , i.e. corresponding to the set value of the pressure limiting valve.
  • the control oil flow is always the same, irrespective of the pressure level, since the pressure in the pressure port of the hydraulic machine is then always higher by the pressure equivalent of the spring 26 than the control pressure, and hence the pressure difference across the nozzle 27 is always the same.
  • the pressure limiting valve 28 has a falling characteristic, i.e. the pressure at the inlet thereof is all the lower, the greater the level of energization of the electromagnet 29 . As a consequence, the pressure limiting valve has its maximum set value if the electric system fails, and the pressure at the pressure port of the hydraulic machine 12 accordingly rises to a maximum.
  • the hydraulic motor 15 is preferably one of axial piston construction, in particular of oblique axis construction, and can be adjusted between a displacement of zero and a maximum displacement. It is connected to the pressure line 14 by a pressure port 35 and to tank 9 by a tank port 36 .
  • the hydraulic motor 15 has an adjusting piston 37 , which is provided on one side with a piston rod 38 and thus separates an annular space 39 on the piston rod side and an adjusting chamber 40 on the opposite side from the piston rod.
  • the inflow and outflow of pressure medium to and from the adjusting chamber 40 is controlled by a control valve 42 , which can be acted upon in a proportional manner by an electromagnet 41 , is mounted on the hydraulic motor 15 and has a pressure port 43 , which is connected to pressure port 35 , a tank port 44 , which is connected to tank 9 via the interior of the housing of the hydraulic motor and a leakage port (not designated specifically), and a control port 45 , which is connected to the adjusting chamber 40 .
  • the annular space 39 has a continuous fluidic connection to pressure port 35 via the housing (not designated specifically) of the control valve 42 .
  • the electromagnet 41 acts on a control piston of the control valve 42 so as to connect the control port 45 to pressure port 43 and so as to reduce the displacement of the hydraulic motor 15 .
  • the control piston So as to connect the control port to the tank port 44 , the control piston is acted upon by a first spring 46 , which is supported in a fixed location relative to the housing and by means of which the start of control can be set, and by a second spring 47 , which is arranged between the control piston and the piston rod 38 , i.e. the adjusting piston 37 .
  • This construction has the effect that the position of the adjusting piston and hence the displacement of the hydraulic motor 15 depends directly on the force of the electromagnet 41 , i.e. on the level of current flowing through the coil of the electromagnet.
  • the adjusting piston In a compensated state, the adjusting piston must namely, on the one hand, be at rest and, on the other hand, there must be an equilibrium of forces on the control piston of the control valve, which is in the control position thereof, irrespective of the position of the adjusting piston.
  • the sum of the forces exerted by the two springs 46 and 47 must therefore be equal to the force of the electromagnet 41 .
  • the force of the spring In the control position of the control piston, the force of the spring is always the same. Therefore, the force of the spring 47 must differ according to the magnetic force. This differing force of the spring 47 results from the differing positions of the adjusting piston 37 , depending on the magnetic force. This kind of adjustment is also known as electroproportional adjustment.
  • the speed of the hydraulic motor 15 and hence that of the fan impeller 16 is detected by a speed sensor 50 , which sends a corresponding signal to an electric control unit 51 .
  • the latter is furthermore supplied with a setpoint speed value, which is determined from the temperature of a medium to be cooled.
  • the control unit 51 then controls the electromagnet 41 in such a way that the desired speed is achieved on the basis of the displacement that is established.
  • a pressure sensor 52 by means of which the pressure in the pressure line 14 is detected.
  • the pressure can thus be used to calculate the displacement that is necessary to produce the driving torque required to reach or maintain the desired speed, and the electromagnet can be controlled accordingly.
  • the hydraulic machine 10 In pure fan mode, the hydraulic machine 10 operates as a hydraulic pump and is set to a pressure value of 150 bar, for example. This pressure prevails in the pressure line 14 and in the hydraulic accumulator 17 . The displacement of the hydraulic motor 15 is then set in such a way that, at the pressure of 150 bar, the driving torque required to drive the fan impeller at the desired speed is obtained. If the electric system fails, the hydraulic machine is set to maximum pressure and the hydraulic motor is set to maximum displacement, thus ensuring adequate cooling of the medium to be cooled in all cases.
  • the setting of the pressure value at the hydraulic machine 10 and hence the state of charge of the hydraulic accumulator 17 can be varied in order, for example, to enable the hydraulic motor 15 to be operated predominantly with a large displacement or to smooth the power to be output by the diesel engine 11 . If the diesel engine is underused at any particular time, the pressure level can be raised briefly while, if it is overloaded, the pressure level can be lowered briefly. By raising the pressure level, it is possible to protect the diesel engine from overspeeding.
  • the braking energy can be used to enable the hydraulic machine 10 to be driven as a hydraulic pump by the vehicle itself.
  • the pressure can be set to a maximum value, with the result that the hydraulic machine 10 adjusts to a maximum swivel angle and the braking effect is the product of the maximum swept volume and the instantaneous pressure in the hydraulic accumulator.
  • Braking energy previously stored in the hydraulic accumulator can thus be used to boost the diesel engine. However, it can also be used to supply the hydraulic motor 15 and hence to drive the fan impeller. In that case, the pressure set at the hydraulic machine should be lowered sufficiently slowly, taking into account the quantity of pressure medium consumed by the hydraulic motor 15 , that the set pressure is not lower than the accumulator pressure.
  • the hydraulic fan drive shown in FIG. 2 includes a hydraulic pump 60 , which can be connected mechanically to a primary unit 61 by a clutch and can be driven by said unit. No motor mode is provided for the machine 60 in this case. Accordingly, the swept volume of the hydraulic pump can be adjusted only between a minimum value close to or equal to zero and a maximum value.
  • the hydraulic pump has a pressure port 62 and a suction port 63 , which is continuously connected to a tank 9 .
  • a pressure line 14 leads from the pressure port 62 to a hydraulic motor 65 , by which a fan impeller 16 can be driven.
  • a hydraulic accumulator 17 is connected to the pressure line and can be operated in a pressure range between 100 bar and 300 bar, for example.
  • There is a check valve 66 in the pressure line 14 between the hydraulic accumulator and the pressure port 62 said check valve blocking flow toward the hydraulic pump 60 .
  • the hydraulic pump 60 is an axial piston pump of swashplate construction, for example.
  • two adjusting pistons of which one adjusting piston 18 , which has a larger effective area than the other adjusting piston, delimits an adjusting chamber 19 , to which pressure medium can be fed and from which pressure medium can be released.
  • This feeding and discharge of pressure medium is controlled by a pressure control valve arrangement 70 mounted on the hydraulic pump 60 .
  • This arrangement includes a continuously adjustable control valve 71 with a zero overlap or a small positive overlap between the control edges and with a pressure port 72 , which is connected fluidically to the pressure port 62 of the hydraulic pump 60 , a tank port 73 , which is connected to a leakage oil port 67 via the interior of the housing of the hydraulic pump 60 , and a control port 74 , which is connected to the adjusting chamber 19 .
  • the valve piston of the control valve is acted upon by the pump pressure so as to connect the control port 74 to the pressure port 62 and so as to reduce the swept volume of the hydraulic pump 60 and exclusively by a spring 75 so as to connect the control port 74 to the tank port 73 and so as to increase the swept volume.
  • the pressure established at the pressure port 62 of the hydraulic pump 60 is in each case the pressure equivalent of the spring 75 , e.g. a pressure of 100 bar.
  • remote adjustment of this pressure is not provided.
  • the setting of the spring 75 can be changed in the course of commissioning or during servicing work.
  • the hydraulic motor 65 is preferably one of axial piston construction, in particular of oblique axis construction, and, like the hydraulic motor 15 in the illustrative embodiment shown in FIG. 1 , can be adjusted between a displacement of zero and a maximum displacement. It is connected to the pressure line 14 by a pressure port 76 and to tank 9 by a tank port 77 .
  • the hydraulic motor 15 has an adjusting piston 78 , which is provided on one side with a piston rod 79 and thus separates an annular space 80 on the piston rod side and an adjusting chamber 81 on the opposite side from the piston rod.
  • the inflow and outflow of pressure medium to and from the adjusting chamber 81 is controlled by a torque control valve arrangement 69 having a control valve 82 , which is mounted on the hydraulic motor 65 and has a pressure port 83 , which is connected to pressure port 76 , a tank port 84 , which is connected to tank 9 via the interior of the housing of the hydraulic motor and a leakage port (not designated specifically), and a control port 85 , which is connected to the adjusting chamber 81 .
  • the annular space 80 has a continuous fluidic connection to pressure port 76 .
  • a control piston of the control valve 82 is acted upon by a spring 86 supported in a fixed location relative to the housing so as to connect the control port 85 to the tank port 84 and so as to increase the displacement of the hydraulic motor 65 , and is acted upon via a control line 87 by a variable control pressure, by means of which a force that can be varied by remote control can thus be exerted on the control piston.
  • the control pressure is advantageously at a maximum if the electric system fails. So as to connect the control port to the pressure port 83 , the control piston is acted upon by a force which depends on the position of the adjusting piston 78 and hence on the displacement of the hydraulic motor 65 and on the pressure in the pressure line 14 .
  • control piston is initially supported on a lever 88 at a distance which is constant in the control position from an axis of rotation of said lever 88 , said axis being fixed relative to the housing.
  • lever 88 is acted upon by way of a rod 89 , which is inserted in a movable manner in the adjusting piston 78 and on which the pressure prevailing in the pressure line 14 acts.
  • the torque produced at the lever 88 by way of the rod thus represents the product of the pressure prevailing at the hydraulic motor 65 and the displacement of the hydraulic motor and hence the output torque of the hydraulic motor.
  • An opposing torque on the lever 88 is produced by the sum of the forces exerted by the spring 86 and the control pressure on the control piston of the control valve 82 .
  • the sum of the torques acting on the lever 88 must be zero. If the pressure in the pressure line 14 rises, for example, the torque exerted on the lever 88 by way of the rod 89 becomes greater than the torque exerted by way of the control piston. The lever is turned and the control piston is moved, thus connecting the control port 85 to the pressure port 83 of the control valve 82 . Pressure medium flows to the adjusting chamber 81 , and the adjusting piston moves in a direction corresponding to a reduction in the displacement. The rod 89 moves with the adjusting piston along the lever 88 , with the result that the lever arm for the pressure force acting via the rod becomes smaller until there is once again an equilibrium between the torques.
  • the hydraulic accumulator 17 makes it possible for the quantity fed in to be larger than the instantaneous quantity being consumed by the hydraulic motor 65 , without the excess quantity being ejected via a pressure limiting valve.
  • FIG. 2 Two possibilities for an additional infeed are shown in FIG. 2 .
  • another hydraulic pump 90 said pump being adjustable in an electroproportional manner, for example, and being able to be coupled to the drive train of the vehicle by means of a clutch 91 .
  • the clutch is closed, and the hydraulic pump 90 is driven by the vehicle and delivers pressure medium into the pressure line 14 via a check valve 92 , which closes in the direction of said pump.
  • the advantage here is that it is always possible to feed in pressure medium, irrespective of the pressure in the fan circuit.
  • the second possibility shown is that of feeding in pressure medium when a load is being lowered, said load being indicated here by a hydraulic cylinder 95 .
  • a flow control valve 96 with a proportionally adjustable metering orifice (not shown specifically) and a pressure compensator arranged in series therewith is provided.
  • a check valve 97 In a branch line 94 between the flow control valve and the pressure line 14 there is a check valve 97 , which blocks flow toward the flow control valve.
  • a 2/2-way valve 98 by means of which a flow to the tank can be opened, is connected to the fluidic connection between the flow control valve 96 and the check valve 97 .
  • pressure medium displaced from the hydraulic cylinder can be fed into the pressure line 14 if the load pressure is higher than the pressure in the pressure line 14 and in the hydraulic accumulator 17 by the pressure drop across the metering orifice of the flow control valve 96 . It may be that this is the situation at the beginning of a lowering movement but that it does not continue since the pressure in the hydraulic accumulator 17 rises.
  • the valve 98 must then be opened. Whether it is still possible to feed in pressure medium can be determined with the aid of pressure sensors which detect the load pressure and the accumulator pressure. Position monitoring of the pressure compensator is also possible. When the pressure compensator is fully open, it is no longer possible to feed in pressure medium.
  • the additional quantity of pressure medium fed in it is possible to distinguish between two cases. If the quantity of pressure medium fed in is less than the consumption of the hydraulic motor 65 , the residual quantity is delivered by the hydraulic pump 60 , and the pressure level in the system remains at the level set at the hydraulic pump 60 . In this case too, an energy saving is achieved since the hydraulic pump 60 swivels to a smaller swept volume.
  • the pressure in the fan circuit rises beyond the level set at the hydraulic pump 60 .
  • the hydraulic pump is adjusted back to zero stroke by cutting off the pressure.
  • the pressure level can then assume a significantly higher value, e.g. 300 bar, until it is limited by a pressure limiting valve 99 connected to the pressure line 14 . If no more or only a smaller quantity is fed in than the hydraulic motor 65 is consuming, the hydraulic accumulator 17 initially takes over the supply of the fan circuit completely or partially until the hydraulic pump 60 swivels back out at a pressure level of 100 bar.
  • an anti-cavitation valve 100 that opens from the tank port to the pressure port 76 is depicted between the pressure port 76 and the tank port 77 .
  • an anti-cavitation valve 100 that opens from the tank port to the pressure port 76 is depicted between the pressure port 76 and the tank port 77 .
  • the fan drive shown in FIG. 3 thus includes a first hydraulic machine 10 , which is so called because it can be operated both as a hydraulic pump and as a hydraulic motor.
  • the hydraulic machine 10 is connected mechanically to a diesel engine 11 . It has a high-pressure port (pressure port) 12 and a low-pressure port (tank port) 13 , which is continuously connected to a tank 9 .
  • a pressure line 14 leads to a hydraulic motor 65 , by which a fan impeller can be driven.
  • a hydraulic accumulator 17 Connected directly to the pressure line is a hydraulic accumulator 17 , which can be operated in a pressure range of between 100 bar and 300 bar, for example, and is charged to 200 bar in normal operation.
  • a pressure limiting valve 99 is also connected to the pressure line 14 .
  • the hydraulic machine 10 is, for example, an axial piston machine of swashplate construction, the swept volume of which can be adjusted via zero between a maximum positive value and a maximum negative value.
  • the hydraulic machine 10 delivers pressure medium into the pressure line 14 as a hydraulic pump.
  • the hydraulic machine operates as a hydraulic motor in the same direction of rotation and is supplied with pressure medium from the pressure line 14 .
  • adjusting piston 18 For adjustment of the swept volume, there are two adjusting pistons and a spring, of which one adjusting piston 18 , which has a larger effective area than the other adjusting piston, delimits an adjusting chamber 19 , to which pressure medium can be fed and from which pressure medium can be released.
  • This feeding and discharge of pressure medium is controlled by a pressure control valve arrangement 20 mounted on the hydraulic machine 10 .
  • This arrangement includes a continuously adjustable control valve 21 with a zero overlap or a small positive overlap between the control edges and with a pressure port 22 , which is connected fluidically to the pressure port 12 of the hydraulic machine 10 , a tank port 23 , which is connected to a leakage oil port 30 via the interior of the housing of the hydraulic machine 10 , and a control port 24 , which is connected via a damping nozzle 25 to the adjusting chamber 19 .
  • the valve piston of the control valve is acted upon by the pump pressure so as to connect the control port 24 to the pressure port 22 and so as to reduce the swept volume of the hydraulic machine 12 as far as negative values and by a spring 26 and a variable control pressure so as to connect the control port 24 to the tank port 23 and so as to increase the swept volume, said control pressure being picked off between a control oil nozzle 27 and a pressure limiting valve 28 that can be adjusted proportionally by an electromagnet 29 , i.e. corresponding to the set value of the pressure limiting valve.
  • the control oil flow is always the same, irrespective of the pressure level, since the pressure in the pressure port of the hydraulic machine is then always higher by the pressure equivalent of the spring 26 than the control pressure, and hence the pressure difference across the nozzle 27 is always the same.
  • the pressure limiting valve 28 has a falling characteristic, i.e. the pressure at the inlet thereof is all the lower, the greater the level of energization of the electromagnet 29 . As a consequence, the pressure limiting valve has its maximum set value if the electric system fails, and the pressure at the pressure port of the hydraulic machine 12 accordingly rises to a maximum.
  • the hydraulic motor 65 in the illustrative embodiment shown in FIG. 3 is preferably one of axial piston construction, in particular of oblique axis construction, and, like the hydraulic motor 15 in the illustrative embodiment shown in FIG. 1 , can be adjusted between a displacement of zero and a maximum displacement. It is connected to the pressure line 14 by a pressure port 76 and to tank 9 by a tank port 77 .
  • the hydraulic motor 15 has an adjusting piston 78 , which is provided on one side with a piston rod 79 and thus separates an annular space 80 on the piston rod side and an adjusting chamber 81 on the opposite side from the piston rod.
  • the inflow and outflow of pressure medium to and from the adjusting chamber 81 is controlled by a torque control valve arrangement 69 having a control valve 82 , which is mounted on the hydraulic motor 65 and has a pressure port 83 , which is connected to pressure port 76 , a tank port 84 , which is connected to tank 9 via the interior of the housing of the hydraulic motor and a leakage port (not designated specifically), and a control port 85 , which is connected to the adjusting chamber 81 .
  • the annular space 80 has a continuous fluidic connection to pressure port 76 .
  • a control piston of the control valve 82 is acted upon by a spring 86 supported in a fixed location relative to the housing so as to connect the control port 85 to the tank port 84 and so as to increase the displacement of the hydraulic motor 65 , and is acted upon via a control line 87 by a variable control pressure, by means of which a force that can be varied by remote control can thus be exerted on the control piston.
  • the control pressure is advantageously at a maximum if the electric system fails. So as to connect the control port to the pressure port 83 , the control piston is acted upon by a force which depends on the position of the adjusting piston 78 and hence on the displacement of the hydraulic motor 65 and on the pressure in the pressure line 14 .
  • control piston is initially supported on a lever 88 at a distance which is constant in the control position from an axis of rotation of said lever 88 , said axis being fixed relative to the housing.
  • lever 88 is acted upon by way of a rod 89 , which is inserted in a movable manner in the adjusting piston 78 and on which the pressure prevailing in the pressure line 14 acts.
  • the torque produced at the lever 88 by way of the rod thus represents the product of the pressure prevailing at the hydraulic motor 65 and the displacement of the hydraulic motor and hence the output torque of the hydraulic motor.
  • An opposing torque on the lever 88 is produced by the sum of the forces exerted by the spring 86 and the control pressure on the control piston of the control valve 82 .
  • the sum of the torques acting on the lever 88 must be zero. If the pressure in the pressure line 14 rises, for example, the torque exerted on the lever 88 by way of the rod 89 becomes greater than the torque exerted by way of the control piston. The lever is turned and the control piston is moved, thus connecting the control port 85 to the pressure port 83 of the control valve 82 . Pressure medium flows to the adjusting chamber 81 , and the adjusting piston moves in a direction corresponding to a reduction in the displacement. The rod 89 moves with the adjusting piston along the lever 88 , with the result that the lever arm for the pressure force acting via the rod becomes smaller until there is once again an equilibrium between the torques.
  • the hydraulic accumulator 17 makes it possible for the quantity fed in to be larger than the instantaneous quantity being consumed by the hydraulic motor 65 , without the excess quantity being ejected via a pressure limiting valve.
  • FIG. 3 the feeding of pressure medium into the pressure line and into the hydraulic accumulator 17 when a load is being lowered is shown, said load being indicated here by a hydraulic cylinder 95 .
  • a flow control valve 96 with a proportionally adjustable metering orifice (not shown specifically) and a pressure compensator arranged in series therewith is provided.
  • a check valve 97 In a branch line 94 between the flow control valve and the pressure line 14 there is a check valve 97 , which blocks flow toward the flow control valve.
  • a 2/2-way valve 98 by means of which a flow to the tank can be opened, is connected to the fluidic connection between the flow control valve 96 and the check valve 97 .
  • pressure medium displaced from the hydraulic cylinder can be fed into the pressure line 14 if the load pressure is higher than the pressure in the pressure line 14 and in the hydraulic accumulator 17 by the pressure drop across the metering orifice of the flow control valve 96 . It may be that this is the situation at the beginning of a lowering movement but that it does not continue since the pressure in the hydraulic accumulator 17 rises.
  • the valve 98 must then be opened. Whether it is still possible to feed in pressure medium can be determined with the aid of pressure sensors which detect the load pressure and the accumulator pressure. Position monitoring of the pressure compensator is also possible. When the pressure compensator is fully open, it is no longer possible to feed in pressure medium.
  • the additional quantity of pressure medium fed in it is possible to distinguish between two cases. If the quantity of pressure medium fed in is less than the consumption of the hydraulic motor 65 , the residual quantity is delivered by the hydraulic pump 60 , and the pressure level in the system remains at the level set at the hydraulic pump 60 . In this case too, an energy saving is achieved since the hydraulic pump 60 swivels to a smaller swept volume.
  • the pressure in the fan circuit rises beyond the level set at the hydraulic pump 60 .
  • the hydraulic pump is adjusted back to zero stroke by cutting off the pressure, it being possible here in addition to employ a swivel angle sensor, by means of which the swivel angle is sensed.
  • the valve 28 would then be set in each case in such a way that the swivel angle is zero or just above zero.
  • the pressure level can then assume a significantly higher value, e.g. 300 bar, until it is limited by a pressure limiting valve 99 connected to the pressure line 14 . If no more or only a smaller quantity is fed in than the hydraulic motor 65 is consuming, the hydraulic accumulator 17 initially takes over the supply of the fan circuit completely or partially until the hydraulic pump 60 swivels back out at a pressure level of 100 bar.
  • an anti-cavitation valve 100 that opens from the tank port to the pressure port 76 is arranged between the pressure port 76 and the tank port 77 of the hydraulic motor 65 .
  • an external energy source e.g. a lifting cylinder in a lowering operation or an additional hydraulic pump to drive the fan impeller.
  • an additional hydraulic pump to drive the fan impeller.
  • brief support of the diesel engine is possible by means of the hydraulic machine 10 .
  • a fan drive according to the invention in particular in a fan drive with EP adjustment of the hydraulic motor in accordance with the illustrative embodiment shown in FIG. 1 or electric adjustment with swivel angle restoration with the aid of an electric swivel angle sensor, it is also possible to use a hydraulic motor that can be swiveled via zero. In this case, the direction of rotation of the fan impeller can be reversed without an additional valve in order to blow the radiator clean. This is advantageous particularly in the case of forestry and construction machines.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Servomotors (AREA)
US13/638,016 2010-03-30 2011-03-03 Hydraulic fan drive Abandoned US20130202452A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102010013453.8 2010-03-30
DE102010013453 2010-03-30
PCT/DE2011/000217 WO2011120486A2 (de) 2010-03-30 2011-03-03 Hydraulischer lüfterantrieb

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US20130202452A1 true US20130202452A1 (en) 2013-08-08

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US13/638,016 Abandoned US20130202452A1 (en) 2010-03-30 2011-03-03 Hydraulic fan drive

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US (1) US20130202452A1 (ko)
EP (1) EP2553231B1 (ko)
JP (1) JP5599504B2 (ko)
KR (1) KR20130018253A (ko)
CN (1) CN102812218B (ko)
DE (1) DE102011012905A1 (ko)
WO (1) WO2011120486A2 (ko)

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US20130227939A1 (en) * 2012-03-05 2013-09-05 Claas Selbstfahrende Erntemaschinen Gmbh Hydraulic system for a self-propelled working machine
CN105650044A (zh) * 2016-03-15 2016-06-08 雷沃重工股份有限公司 收获机用紧急制动系统及其制动方法
CN106013315A (zh) * 2016-06-30 2016-10-12 徐州徐工挖掘机械有限公司 一种挖掘机回收能量利用系统
CN106715925A (zh) * 2014-09-15 2017-05-24 罗伯特·博世有限公司 流体静力的驱动装置
US20170233080A1 (en) * 2016-02-16 2017-08-17 Rolls-Royce Plc Cabin blower system
US10330126B2 (en) * 2016-12-16 2019-06-25 Caterpillar Inc. Fan control system with electro-hydraulic valve providing three fan motor operational positions
CN114233704A (zh) * 2021-11-05 2022-03-25 江苏柳工机械有限公司 臂架式高空作业平台的工作液压系统及其控制方法

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CN108194388A (zh) * 2016-05-04 2018-06-22 何春晖 一种风扇
CN105971053B (zh) * 2016-06-30 2018-02-13 徐州徐工挖掘机械有限公司 一种挖掘机节能系统
DE102017011905A1 (de) * 2017-12-21 2019-06-27 Wabco Gmbh Verfahren und Einrichtung zum Betreiben eines pneumatischen Systems mit einer Druckluftversorgungsanlage und einer Luftfederanlage und pneumatisches System mit einer Druckluftversorgungsanlage und einer Luftfederanlage sowie Fahrzeug
CN108644001B (zh) * 2018-07-13 2024-02-09 安徽合力股份有限公司 一种液压马达驱动的智能散热系统及其散热方法
DE102019215885A1 (de) * 2019-10-16 2021-04-22 Robert Bosch Gmbh Verstelleinrichtung und Hydromaschine
DE102020200958A1 (de) 2020-01-28 2021-07-29 Robert Bosch Gesellschaft mit beschränkter Haftung Hydraulisches Antriebssystem mit nach unten begrenztem Förderdruck der Pumpe
CN112942480B (zh) * 2021-01-29 2022-05-24 徐州徐工挖掘机械有限公司 混合动力工程机械液压系统以及混合动力工程机械
CN113847297A (zh) * 2021-10-19 2021-12-28 徐工消防安全装备有限公司 一种电负载敏感系统及其控制方法

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US20130008246A1 (en) * 2011-07-08 2013-01-10 Caterpillar Inc. Hydraulic accumulator fluid charge estimation system and method
US8984872B2 (en) * 2011-07-08 2015-03-24 Caterpillar Inc. Hydraulic accumulator fluid charge estimation system and method
US20130227939A1 (en) * 2012-03-05 2013-09-05 Claas Selbstfahrende Erntemaschinen Gmbh Hydraulic system for a self-propelled working machine
CN106715925A (zh) * 2014-09-15 2017-05-24 罗伯特·博世有限公司 流体静力的驱动装置
US20170233080A1 (en) * 2016-02-16 2017-08-17 Rolls-Royce Plc Cabin blower system
US10494105B2 (en) * 2016-02-16 2019-12-03 Rolls-Royce Plc Cabin blower system
CN105650044A (zh) * 2016-03-15 2016-06-08 雷沃重工股份有限公司 收获机用紧急制动系统及其制动方法
CN106013315A (zh) * 2016-06-30 2016-10-12 徐州徐工挖掘机械有限公司 一种挖掘机回收能量利用系统
US10330126B2 (en) * 2016-12-16 2019-06-25 Caterpillar Inc. Fan control system with electro-hydraulic valve providing three fan motor operational positions
CN110050113A (zh) * 2016-12-16 2019-07-23 卡特彼勒公司 具有提供三个风扇电动机操作位置的电动液压阀的风扇控制系统
CN114233704A (zh) * 2021-11-05 2022-03-25 江苏柳工机械有限公司 臂架式高空作业平台的工作液压系统及其控制方法

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JP2013524107A (ja) 2013-06-17
EP2553231B1 (de) 2014-01-01
KR20130018253A (ko) 2013-02-20
WO2011120486A2 (de) 2011-10-06
CN102812218A (zh) 2012-12-05
EP2553231A2 (de) 2013-02-06
CN102812218B (zh) 2015-07-22
DE102011012905A1 (de) 2011-10-06
JP5599504B2 (ja) 2014-10-01
WO2011120486A3 (de) 2012-01-05

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