DE102016000186A1 - Device for the controllable hydraulic supply of differently regulated hydraulic consumers as well as hydraulic system and working machine - Google Patents

Abstract

The invention relates to a device for controllable hydraulic supply of at least two connectable hydraulic consumers, of which at least one pressure-controlled and at least one volume-controlled operation, wherein the device comprises a variable displacement pump for the common pressure supply of at least two consumers and a control arrangement for controlling the variable displacement is provided comprising a pressure control of the variable displacement pump and a volume control of the variable displacement override pressure control with a corresponding amount request.

Description

The invention relates to a device for controllable hydraulic supply of at least two connectable hydraulic consumers, of which at least one is pressure-controlled and at least one volume-controlled operable. Moreover, the invention relates to a hydraulic system with such a device and a working machine with such a hydraulic system.

When constructing the hydraulic system, a construction machine is usually distinguished between the working hydraulics (working hydraulic circuit), whose consumers are responsible for the functions of the equipment, and the rest of the hydraulics with the secondary consumers (secondary consumer circuit). The working hydraulics are preferably operated by an adjustable hydraulic pump and include all the hydraulic components for carrying out the construction functions, that is the operation of the equipment and the implements. The secondary consumer group with the secondary consumers is usually operated by several differently regulated hydraulic pumps and provides other necessary for the operation of the construction machine functions, such as a hydraulic engine ventilation, a hydraulic steering and / or a hydraulic brake, etc ..

In view of the various functions of the secondary consumers, their regulation often takes place differently. In principle, a distinction is made between a pressure and flow control of the connected auxiliary consumers. Due to the different control concepts, the secondary consumers are therefore fed by differently regulated auxiliary consumer pumps. Ie. a pressure-controlled auxiliary consumer pump supplies a pressure-controlled consumer, while a separate volume-controlled auxiliary consumer pump operates a volume-controlled consumer. In the event that a pressure-controlled auxiliary consumer temporarily requires no hydraulic energy or claimed, but the feeding pump continues to run with the result of energy inefficiency, since the pump control always provides a constant pressure. A combination of different pump systems (eg pressure-controlled adjustable hydraulic pumps, volume-controlled adjustable hydraulic pumps ...) to a common hydraulic pump could not be done so far due to various control principles and the resulting high susceptibility to vibration or construction complexity.

From the DE 10 2014 001 369 One possible approach to the above problem is disclosed. However, the focus here is not on the adaptation of the scheme, but on the integration of a hydraulic pressure accumulator, which is filled by an adjustable and volume-controlled hydraulic pump and the hydraulic pressure to the pressure-controlled secondary consumers then and according to its volume capacity temporarily available. A disadvantage of this system is the integration of such a hydraulic pressure accumulator and the insufficient operating efficiency, which arises inter alia from friction losses in the pressure accumulator and by the constant switching on and off of the adjustable hydraulic pump.

Previous control arrangements adjustable hydraulic pumps consist predominantly of series-connected controllers, eg. B. a load-sensing controller - hereinafter called LS controller - and a power controller - hereinafter called LR controller (see. 1 ). In such an arrangement, each of the regulators connected in series 13 and 15 a direct access to the parking chamber 17 the adjustable hydraulic pump 18 , As a result, the flow rate of the hydraulic pump 18 through each regulator 13 . 15 be regulated alone. With such control arrangements, however, either only quantity-controlled or only pressure-controlled auxiliary consumers can hitherto be supplied with hydraulic energy. A merger, as described above, could not be done so far inter alia due to the operation of the pressure regulator - hereinafter called DR regulator. A DR regulator limits the maximum hydraulic pressure at the pump outlet within the control range of a pump. In a series connection of DR controller with LS controller, the adjustable hydraulic pump would be forced to swing back when reaching a defined maximum pressure, since the DR regulator relieves the line to the tank. However, the pivoting back of the adjustable hydraulic pump caused by the DR regulator would also occur if at the same time the quantity-controlled secondary consumers request more hydraulic energy through the LS regulator. For this reason, pressure- and volume-controlled consumers have previously been supplied by separate pumps.

The aim of the invention is therefore to find a suitable controller arrangement, which allows a regulation of a volume-controlled consumer and a pressure-controlled consumer by a common variable.

This object is achieved by a device according to the features of claim 1. Advantageous embodiments of the invention are the subject of the subsequent dependent on the main claim dependent claims.

According to the invention, it is proposed to provide at least two differently regulated hydraulic consumers with pressure via a common variable displacement pump. The proposed device comprises a regulator arrangement for controlling the common variable displacement pump for the at least two consumers, on the one hand provide a pressure control of the variable displacement pump to adjust the output pressure to the desired target pressure of the pressure-controlled consumer, and on the other hand comprise a volume control, the corresponding Quantity request of the consumer provide the desired volume flow at the pump outlet. The combination of both control methods is achieved by appropriate interconnection of the pressure and flow control, which ensures an override of the pressure control by the flow control with a corresponding amount request. The variable displacement pump is regulated by the pressure control to the desired setpoint pressure of the pressure-controlled consumer. If the requested quantity of the volume-controlled consumer exceeds the outgoing volume flow, the volume control of the device overrides the pressure regulation of the device so that the variable-displacement pump is operated with the desired volume flow of the volume-controlled consumer.

This procedure makes it possible for two differently regulated consumers to be fed with one and the same variable displacement pump. The previously known from the prior art approach, d. H. To feed differently regulated consumers with separate variable displacement pumps or to integrate hydraulic pressure accumulators for temporary energy storage is thereby avoided. Additional pumps or hydraulic accumulators and the associated costs in a hydraulic circuit can be saved. Also can be increased by the invention, the energy efficiency, since various gear pumps and / or hydraulic accumulator can now be replaced by a variable displacement.

According to an advantageous embodiment of the invention, the flow control provides a load-sensing input that can be connected to a volume-controlled consumer. The load-sensing signal input, also referred to below as an LS signal, characterizes, for example, the requested volume quantity of the consumer. Depending on the LS signal, the quantity control can set the corresponding volume of the variable displacement pump, possibly with override of the pressure control. If the quantity of volume provided by the pressure control is sufficient for the quantity-controlled consumer, on the other hand, there is no overload.

According to a particularly preferred embodiment of the invention, the flow control is so connected to the pressure control, so that triggered by the pressure control reduction of the displacement of the variable in case of need is overridden, thereby reducing the reduction of the displacement by the pressure control to reduce or completely prevent. Optionally, an increase in the displacement volume can be achieved contrary to the pressure control.

The pressure control and / or flow control ideally consist of continuously variable directional control valves, preferably of 3/2-way valves with two control connections, ideally one is hydraulically actuated and the counteracting control port is electrically (solenoid), pneumatic, hydraulic, mechanical or manually operable.

In this context, it is advantageous if the directional control valve of the pressure control is connected on the input side to the output of the variable displacement pump and on the output side with an adjusting means for increasing the displacement volume of the variable displacement pump.

The variable displacement pump can be hydraulically-mechanically adjustable, for example. In this case, an adjusting cylinder proves to be suitable as adjusting means. For example, the directional control valve of the pressure control is connected to a control chamber of the adjusting cylinder, the pressurization of which triggers a mechanical actuation of the variable displacement pump. In particular, an increase in pressure within the actuating chamber leads to an increase in the displacement volume. A return flow from the control chamber leads to a reduction of the displacement volume. It is conceivable in this context that the pressurization of the adjusting chamber causes an extension of the piston rod, whereby the pump is swung out and the delivery volume of the variable displacement pump is increased.

It is particularly useful if only the pressure control has a direct access to the control chamber of the adjusting cylinder. The flow control has no direct access to the control chamber, but can relieve or prevent or inhibit a backflow of hydraulic medium from the control chamber via the pressure regulator either in the hydraulic tank.

The directional control valve of the pressure control preferably comprises a pilot control for setting a desired pressure level. The precontrol can be done for example on the basis of an electromagnet, preferably an adjustable electromagnet. It is useful in this Connection, when a second control line of the directional control valve of the pressure control, which counteracts the pilot control of the directional control valve, is in communication with the output of the variable displacement pump. This interconnection of the pressure control valve with the variable displacement causes a desired set pressure to be set at the output of the variable displacement pump.

The flow control of the directional control valve may be connected, for example, on the input side to the output of the variable displacement pump and on the output side to the second input of the directional control valve of the pressure control. Also, the directional control valve of the flow control, a control pressure counteracting the adjustable second control line is provided, which is also connected to the output of the variable displacement and / or with the adjusting chamber counteracting cylinder chamber of the adjusting cylinder.

The design of the directional control valve of the pressure control comprises a first end position, in which a volume flow from the pump outlet to the control chamber and in the second end position a return flow from the control chamber to the directional control valve of the flow control is provided. The directional control valve of the flow control preferably has in a first end position a volume flow from the pump outlet to the directional control valve of the pressure control and in a second end position a return flow from the directional control valve of the pressure control into the hydraulic tank. In this case, it is possible that the return flow of the pressure control valve is braked or blocked by appropriate switching position of the flow control valve. This valve position of the flow control valve (flow from the pump outlet to the directional control valve of the pressure regulator) can be used to override the pressure control. The switching position of the quantity control valve, in particular the degree of override, is influenced by the load-sensing input as a control input, i. H. by the volume requirement of the volume-regulated consumer.

To protect the variable displacement pump, a power regulator may additionally be integrated, preferably in the form of a mechanical or electrical regulator. The capacity regulator regulates the variable displacement pump to a constant level of performance to protect against overstressing. An integration of the power controller between the pressure regulator and the variable displacement pump is preferred. Particularly preferably, this is connected in series with the pressure regulator, d. H. Both pressure regulator and power regulator provide access to the adjusting chamber of the adjusting cylinder in a switching position. If the power of the variable displacement pump exceeds the maximum power level, the power regulator relieves the adjusting chamber into the tank and the variable displacement pump is swiveled back. This reflux via the power controller is preferably not overridden by the flow regulator. The power regulator can also be designed as a 3/2-way valve.

In addition to the device according to the invention, the invention also relates to a hydraulic system with at least one volume-controlled hydraulic consumer and at least one pressure-controlled consumer, wherein the system further comprises at least one device according to the present invention for supplying pressure to the consumer. Obviously, the hydraulic system has the same advantages and properties as already explained with reference to the device according to the invention. A repetitive description is omitted for this reason.

In an advantageous embodiment of the hydraulic system, the at least two consumers via a switchable priority valve with the supply pressure output of the device, d. H. the output of the variable, be connected. The priority valve serves to prioritize the pressure supply of the individual consumers from the device. The priority valve may be a continuously switchable directional control valve, wherein a first end position of the priority valve provides an exclusive pressure supply of the volume-controlled consumer and a second end position allows a parallel pressure supply of both consumers from the device.

A load-sensing output of the quantity-controlled consumer is preferably connected to the load-sensing input of the quantity regulator of the device, said load-sensing output also continues to be applied as a control input to the priority valve. Accordingly, not only the quantity control of the device can be controlled by the quantity requirement of the quantity-controlled consumer, but also the switching position of the priority valve can be influenced in order to preferably prioritize the quantity-controlled consumer.

An increase of the delivery volume from the variable displacement pump, taking into account the load-sensing signal of the volume-controlled consumer requires at the same time an undesirable increase in power, for example, torque increase, the pressure-controlled consumer. This can be counteracted by a pressure relief valve, which is installed between priority valve and pressure-controlled consumer. The pressure relief valve limits the pressure level applied to the consumer to the desired target pressure level if the pressure regulator of the device is overridden. An optimized control of the pressure limiting valve is preferably achieved by a coupling with the pressure regulator of the device. A such coupling can be hydraulic or electrical type.

According to a preferred embodiment of the invention, the pressure-controlled consumer may be a hydraulic fan motor and the quantity-controlled consumer is a hydraulic steering system.

In addition to the hydraulic system, the present invention also relates to a work machine, in particular a hydraulic excavator, with at least one hydraulic system according to the present invention. According to a preferred embodiment, the hydraulic system is part of a secondary consumer circuit or even forms a secondary consumer circuit of the entire hydraulic system of the machine. The total hydraulic system is divided into a working hydraulic circuit and a secondary consuming circuit. The working hydraulic circuit is preferably used to control the attachments necessary for the machine work, while the secondary consuming circuit controls subcomponents of the working machine, such as a hydraulic steering system and a fan motor.

Further advantages and features of the invention will be explained in more detail below with reference to the embodiment shown in the figures.

Show it:

1 A Conventional Regulator Arrangement for Supplying Equally Regulated Hydraulic Consumers

2 the device according to the invention for supplying pressure to differently regulated hydraulic consumers,

3 a hydraulic system according to the invention with the device according to the invention according to FIG 2 and

The conventional regulator arrangement according to 1 has already been discussed in the introductory part of the description. The invention will be described below with reference to the embodiment of 2 . 3 be illustrated. An alternative proposal is subsequently facing 4 discussed.

Given is a variable displacement pump 28 for the open circle 20 with a regulator arrangement 21 , The variable pump 28 is hydraulically-mechanically adjustable by means of the adjusting cylinder. By pressurizing the control chamber 27 the piston rod of the adjusting cylinder is extended, causing the pump 28 is swung out and the displacement volume increases.

The regulator arrangement 21 includes a flow regulator 25 (LS controller), a pressure regulator 24 as well as a power regulator 23 , All controllers 23 . 24 . 25 are designed as continuously switchable 3/2 way valves. The power controller 23 is optional and may be mechanically or electrically switching, in which case a mechanical regulator is shown in the figure representation. Because the function of the power controller 23 is known, this is mentioned only briefly. For the sake of simplicity, it is assumed for the following explanation of the operation of the device that the power regulator 23 is always switched and a flow from the pressure regulator 24 to the control chamber 27 allows.

The flow regulator 25 is a load-sensing controller (LS controller) that receives an LS signal X2 from a connected volume-controlled hydraulic consumer. The flow regulator 25 has two end positions a, b, wherein the first end position a is the output line lying at the second valve inlet 3 the variable displacement pump 28 over the line 26 with the pressure regulator 24 connected. The first valve input is blocked. In the second switching position b, we return from the valve outlet, ie the line 26 from the pressure regulator 24 switched into the hydraulic tank, while the second valve input remains locked. The flow regulator 25 has due to the interconnection with the pressure regulator 24 no direct access to the control chamber 27 However, over the line 26 the DR controller 24 with an appropriate quantity requirement override and the pump 28 continue to deflect. More below.

The IR controller 23 as well as the pressure regulator 25 are connected in series, ie both have direct access to the control chamber 27 the pump. The pressure regulator 24 also includes two end positions a, b. In the first end position a there is a flow from the second input, via line 2 with the output of the variable pump 28 is connected to the power controller connected on the output side 23 or the adjusting chamber 27 , The first input remains locked. In the second end position b, the second valve input is blocked and a return flow from the output, ie the adjusting chamber 27 , to the first entrance 26 , ie to the flow regulator 25 is switched.

The desired target pressure for a pressure-controlled consumer can be controlled by a pilot control 7 of the pressure valve 24 , ie adjust the electromagnet. As a second control input 4 , the electromagnet 7 counteracts, the output of the variable is on the pressure regulator 24 created. Due to the applied control pressures, a pressure equilibrium is established at the valve, so that the variable displacement pump 28 with the desired target pressure is operated. It should be noted that the adjustment chamber 27 counteracting cylinder chamber also with the pump output line, ie the valve lines 2 . 3 connected is.

At the beginning there is the pressure regulator 24 in the end position a, the pumped volume flow of the pump 28 leads to the pressurization of the adjusting chamber 27 , the pump 28 pans completely. At the same time, however, via the control line 4 generates a back pressure, so that the valve 24 steadily towards end position b switches. If the pump pressure exceeds the set target pressure, the pressure regulator switches 24 to reflux and fluid can escape from the control chamber 27 over the pressure regulator 24 to the tank. The pump 28 pans back. It is assumed that the flow regulator 25 due to the pump pressure via the second control line 5 pushes against the bias of the spring in the end position b. However, a back pressure can be generated via the control input X2, so that the flow regulator 25 remains in the end position a. In this case, the pump pressure acts on the input line 3 the return flow from the pressure regulator 24 over the line 26 contrary, the pressure reduction of the control chamber 27 is blocked and the pump 28 hindered from swinging backwards. The flow regulator 25 can therefore the pressure regulator 24 override.

When the maximum pump power is exceeded, the power controller can switch to the end position b and the positioning chamber 27 in the tank relieve to the pump 28 to swing back.

The purpose of this controller arrangement 21 will be described below using the system according to 3 to be discribed. The system includes the device of 2 together with the variable displacement pump 20 and the regulator assembly 21 , Connected to the device are a pressure-controlled consumer (in this case a fan motor 43 ) and a volume-regulated consumer (in this case the steering with steering valve 30 and steering cylinder 31 ). Both consumers 31 . 43 are via a priority valve 41 linked together. The priority valve is also a continuously switching 3/2-way valve whose input is linked to the pump output of the device and its outputs to both consumers 31 . 43 to lead. The LS input X2 of the flow controller 25 becomes a valve pressure of the steering valve 30 fed. This valve pressure is simultaneously the priority valve 41 fed as control pressure. The valve pressure is characteristic of the currently required volume amount to perform a steering movement.

Between fans 43 and priority valve 41 is also still a pressure shut-off valve 42 integrated that the maximum pressure on the fan motor 43 limited. For the operation of the system described below, the function of the power controller 23 disregarded as its function is known. The following operating conditions are possible:
In the first state, the fan motor is in operation, the steering is not actuated. Since no LS signal X2 acts on the part of the steering, the required fan pressure of the fan motor 43 by means of the DR controller 24 set to the appropriate value and the priority valve 41 according to position 41b connected. This releases the fan duct and the fan motor 43 rotated at the required speed.

In the second state is the fan motor 43 in operation and the steering is actuated, but the steering pressure is less than the fan pressure. Due to the parallel operation of the steering 30 the LS signal acts on the priority valve 41 , making this on position 41a on. The required amount of oil for the steering now flows to the steering valve 30 ,

In the third state is the fan motor 43 in operation and the steering is actuated, but the steering pressure is greater than the fan pressure. If now the steering pressure is higher than the preset fan pressure, by means of the LS-valve 25 the pressure regulator 24 overdriven and the pump 28 prevented from swinging back or swung so far until the system is saturated or the pump 28 stands on the largest sip volume. Since the higher system pressure directly the speed of the fan motor 43 its speed is controlled by means of the pressure shut-off valve 42 limited. The pressure shut-off valve 42 can for better fan control with the pressure control valve 24 be linked, for example, hydraulically or electrically 42b ,

The pump can, as shown here, via a power regulator 23 secured or protected by a simple pressure truncation.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014001369 [0004]

Claims (15)

Device for controllable hydraulic supply of at least two connectable hydraulic consumers, of which at least one pressure-controlled and at least a volume-controlled operation, characterized in that the device comprises a variable displacement pump for the common pressure supply of at least two consumers and a regulator arrangement is provided for controlling the variable displacement comprising a pressure control of the variable displacement pump and a volume control of the variable displacement override pressure control with a corresponding amount request. Apparatus according to claim 1, characterized in that the quantity control takes place as a function of a traceable from the volume-controlled consumer LS signal. Device according to one of the preceding claims, characterized in that the flow control is connected in such a way with the pressure control, so that a triggered by the pressure control reduction of the displacement volume of the variable displacement is overridden to reduce the reduction of the displacement volume or to prevent. Device according to one of the preceding claims, characterized in that the pressure control and / or flow control comprise at least one continuously adjustable directional control valve. Apparatus according to claim 4, characterized in that the directional control valve of the pressure control is connected on the input side to the output of the variable displacement and the output side with an adjusting means for increasing the displacement volume of the variable displacement, preferably with a control chamber of an adjusting cylinder for mechanically increasing the displacement volume of the variable, wherein a adjustable control pressure counteracting second control line of the directional control valve is also connected to the output of the variable displacement pump. Apparatus according to claim 4 or 5, characterized in that the directional control valve of the flow control on the input side is connected to the output of the variable displacement pump and the output side to a second input of the directional control valve of the pressure control, wherein an adjustable control pressure counteracting second control line of the directional control valve also with the output of the variable and / or with the adjusting chamber counteracting cylinder chamber of the adjusting cylinder is connected. Device according to one of the preceding claims 4 to 6, characterized in that the directional control valve of the pressure control in a first end position provides a volume flow from the pump outlet to the control chamber and in the second end position, a return flow from the control chamber to the directional control valve of the flow control and wherein the directional control valve of the flow control in the first end position provides a flow from the pump outlet to the directional control valve of the pressure control and in the second end position, a return flow from the directional control valve of the pressure control in the hydraulic tank. Device according to one of the preceding claims, characterized in that a power regulator for power control of the variable displacement pump is connected in series with the pressure regulator, in particular between pressure control and variable displacement is connected. Hydraulic system with at least one volume-controlled hydraulic consumer and at least one pressure-controlled consumer and at least one device for supplying pressure to the consumer according to one of the preceding claims. Hydraulic system according to claim 9, characterized in that the at least two consumers are connected via a switchable priority valve to the supply pressure output of the device, wherein an end position of the priority valve provides an exclusive pressure supply of the volume controlled consumer and a second end position a parallel pressure supply of both consumers from the device. Hydraulic system according to claim 10, characterized in that an LS output of the quantity-controlled consumer communicates with the LS input of the quantity regulator, wherein the LS output of the quantity-controlled consumer preferably also applied as a control input of the priority valve. Hydraulic system according to one of claims 9 to 11, characterized in that between the priority valve and pressure-controlled consumer, a pressure shut-off valve for pressure limiting is integrated. Hydraulic system according to claim 12, characterized in that the pressure shut-off valve is coupled to the pressure control of the device, preferably electrically or hydraulically. Hydraulic system according to one of claims 9 to 13, characterized in that it is the pressure-controlled consumer to a hydraulic fan motor and the quantity-controlled Consumers are dealing with a hydraulic steering system. Work machine, in particular hydraulic excavator, with at least one hydraulic system according to one of claims 9 to 14, wherein the hydraulic system is preferably part of a secondary consumer circuit of the entire hydraulic system of the working machine.

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