DE102009023667A1 - Valve-controlled radial piston machine for use as radial piston pump, has piston supported at rotatable lifting arc, where lifting arc has cam sections, and cylinder piston units evenly distributed at circumference of cylinder body - Google Patents

Abstract

The machine has two cylinder-piston-units with high pressure valves electrically or electro hydraulically controlled by high pressure side output stages and/or low pressure valves (20a, 20b) electrically or electro hydraulically controlled by low pressure-lateral output stages (22). A piston (12a) is supported at a rotatable lifting arc (18), where the lifting arc has cam sections (18a, 18b). The cylinder piston units are evenly distributed at circumference of a cylinder body (1). The lifting arc is formed at an outer circumference of an eccentric shaft. The high pressure valve and/or the low pressure valve are designed as a 2/2-way valve.

Description

The The invention relates to a valve-controlled radial piston machine according to the Preamble of claim 1.

at Radial piston machines used as hydrostatic motors or pumps can be used, several cylinder-piston units are star-shaped arranged. It is between radial piston engines with inner and distinguished with outer piston support. The former have an inner eccentric shaft, on its eccentric outer circumference the pistons support themselves during radial piston engines with outer piston support an outer ring have, on whose eccentric inner circumference the pistons are supported. In both cases runs with fixed cylinders and upon rotation of the eccentric each piston end on the circumference of the eccentric along which, with each revolution of the eccentric each piston a power stroke, so a hub to the central axis of the machine and away from the central axis of the machine.

Everyone Cylinder-piston unit of a radial piston engine are a low pressure valve and associated with a high pressure valve. For radial piston pumps z. B. the low pressure valve, a check valve and the high pressure valve a pressure switching valve that exceeds a maximum pressure in the cylinder (at the beginning of the compression stroke of the piston) opens and the cylinder with the high pressure port of the radial piston pump combines.

In the publication WO 2006/109079 A1 is a radial piston machine shown with a first cam ring, which consists of several star-shaped cylinder-piston units. The machine is designed as a Digital Displacement Unit (DDU), in which the valves of the respective unit are separately electronically controllable, so that individual units of the machine can be switched powerless or ineffective.

Thereby can this be their delivery volume (in the case of a radial piston pump) or their intake volume (in the case of a radial piston engine) can be reduced.

Farther The Radialkobenmaschine has a second cam ring along the Rotary axis spaced from the first cam ring is arranged, and the The first cam ring is basically similar. The cylinders of the second cam ring are each a on and zuusteuerbaren Channel connected to a cylinder of the first cam ring. Thereby can the flow volume or the sip volume of the machine through Switching on or off the second cam ring additionally changed become. With a connection (for enlargement the delivery or intake volume) are the cylinders of the secondary cam ring via the high-pressure and low pressure valve of the connected primary cylinder and supplied via the connecting channel with pressure medium.

adversely on such valve-controlled radial piston machines (DDU's) the space required along its axis of rotation.

the In contrast, the invention is based on the object, a to create compact valve-controlled radial piston engine (DDU), whose Effort for the electrical system (for a given flow rate) is low.

These Task is solved by a valve-controlled radial piston machine or DDU according to claim 1.

Further advantageous embodiments of the invention are in the dependent Claims described.

The Radial piston engine according to the invention has at least two cylinder-piston units, those of high-pressure side power amplifiers electrically or electro-hydraulically controllable high pressure valves and / or low-pressure-side output stages controllable low-pressure valves are assigned, and further has a rotatable lift curve, at the the pistons were supported. The lift curve has at least according to the invention two cam sections. As a result, a radial piston machine is created, whose pistons per revolution of the lifting curve at least two working cycles (Up and down). Thus, this is swallowing or delivery volume with unchanged space multiplied by the number of cam sections. Each power amplifier can control several equally timed valves, whereby the number of output stages compared to the state of Technology can be reduced. Thus, the effort for the electrical system (unchanged from the prior art Flow) reduced.

there it is preferred if the cylinder-piston units are uniform on the circumference of a cylinder body and the cam sections evenly distributed around the circumference of the lift curve.

In a particularly preferred embodiment of the radial piston engine according to the invention, the number of high-pressure side end stages and / or the number of low-pressure side end stages is [number of cylinder-piston units] / [number of cam sections]. This minimizes the number of power amplifiers. For example, with six cylinder piston units and two cam sections, the number of high pressure side Amplifiers (compared to the prior art) can be halved from six to three.

at a preferred embodiment controls each High-pressure end stage [number of cylinder-piston units] / [number the high-pressure end stages] high-pressure valves, and / or each Low-pressure end stage controls [number of cylinder-piston units] / [number low-pressure end stages] Low-pressure valves. For example, controls in six cylinder-piston units and three low-pressure side Amplifiers each final stage the low pressure valves of two units.

at an alternative particularly preferred embodiment corresponds to the number of high pressure valves and / or the number the low pressure valves the number of the respective power amplifiers. there is every valve over n hydraulic lines with n cylinders where n is the number of cam sections. By the reduced compared to the prior art number of Valves and electrical lines from the power amplifiers to the valves is the device technical effort of the invention Radial piston machine further reduced.

ever According to design, it may be advantageous, the lift curve or the cam sections on the outer circumference of an eccentric shaft or on the inner circumference of a To arrange lifting ring.

at a particularly preferred embodiment is the Radial piston machine a radial piston pump with eight cylinder piston units, with two cam sections, with four high-pressure end stages and with four low-pressure-side output stages, each cylinder-piston unit a high pressure valve and a low pressure valve is associated.

at another particularly preferred embodiment the radial piston machine is a radial piston pump with eight cylinder piston units, with two cam sections, with four high-pressure end stages and with four low-pressure-side output stages, each high-pressure side Final stage, a high-pressure valve and each low-pressure side amplifier associated with a low pressure valve, and wherein each high pressure valve and each low-pressure valve via two hydraulic lines connected to two cylinders.

each High pressure valve and / or each low pressure valve can be a 2/2-way valve be, whose valve body is a spring-biased shut-off and an activated by the corresponding output stage Durchlassstellung Has.

in the Below are various embodiments with reference to the figures the invention described in detail. Show it:

1 a first embodiment of a radial piston pump (DDU) according to the invention with double cam and paired together power amplifiers in a schematic representation;

2 a second embodiment of a radial piston pump (DDU) according to the invention with double cam and paired together power amplifiers and in addition with paired together cylinders in a schematic representation;

3 a diagram of the flow rate of a low pressure valve of a radial piston pump (DDU) with single cam according to the prior art;

4 a diagram of the flow rate of a low pressure valve of a radial piston pump (DDU) according to the invention with double cam and with pairs hydraulically combined cylinders; and

5 a diagram for the flow rate of a low-pressure valve of a radial piston pump (DDU) according to the invention with double cam and pairwise hydraulically combined cylinders at (compared to a comparable radial piston machine according to the prior art 3 ) halved drive speed.

1 shows a first embodiment of a radial piston pump according to the invention in a schematic representation. It has a fixed cylinder body 1 with eight evenly distributed on the circumference radially arranged cylinders 2a . 2 B . 4a . 4b . 5a . 5b . 6a . 6b , In each cylinder is a piston 12a . 12b . 14a . 14b . 15a . 15b . 16a . 16b taken, which is displaceable in the radial direction of the radial piston pump.

In the center of the cylinder body 1 is arranged a drive shaft, which in the area of the cylinder-piston units a double cam 18 having. It has the form of an elliptical disc, whereby in its (in 1 ) shown rotational position their longer axis vertically and their shorter axis are arranged horizontally.

On the outer circumference of the double cam 18 the pistons support themselves 12a . 12b . 14a . 14b . 15a . 15b . 16a . 16b via a respective (not shown) from role.

Through the double cam 18 are each pairwise opposite cylinder-piston units in the same operating state, so are z. B. the two pistons 12a . 12b according to 1 in the retracted state or in their respective top dead center, since their roles on each of the two cam sections 18a . 18 abut while z. B. the two pistons 14a . 14b in the extended state or at bottom dead center.

According to the design of the radial piston pump as a digital displacement unit (DDU) are per cylinder 2a . 2 B . 4a . 4b . 5a . 5b . 6a . 6b each provided an electrically controllable high-pressure valve and in each case an electrically controllable low-pressure valve, wherein in 1 as an example, the low-pressure valve 20a of the cylinder 2a and the low pressure valve 20b of the cylinder 2 B are shown. The low pressure valves 20a . 20b are in the (in 1 shown) spring-biased basic positions of their valve body open. By energizing the respective low pressure valve 20a . 20b associated electromagnet is the connection from the respective cylinder 2a . 2 B shut off to the low pressure port ND of the radial piston pump. In cooperation of each low-pressure valve 20a . 20b With the associated (not shown) high-pressure valve, each cylinder-piston unit can be switched active or inactive, whereby the delivery volume of the radial piston pump can be changed gradually.

In the radial piston pump according to the invention, in each case the two high-pressure valves of two opposing cylinders and in each case the two low-pressure valves of two opposing cylinders are electronically controlled by a common output stage. This results in accordance with the radial piston pump according to the invention 1 four power amplifiers for controlling high pressure valves (not shown) and four power amplifiers for controlling the four pairs of low pressure valves, wherein 1 an example of an amplifier 22 for controlling the valve pair 20a . 20b is shown.

Here is the power amp 22 via an electrical control signal line 24a with a lifting magnet 28a of the low pressure valve 20a and with an electrical control signal line 24b with a lifting magnet 28b of the low pressure valve 20b connected.

In the following, the function of the first embodiment of the radial piston pump according to the invention according to 1 explained. The four pairs of opposing cylinder-piston units are due to the symmetry of the double-cam 18 each in the same operating states, wherein in addition to the positions of the two opposing pistons and their directions of movement (with respect to the respective cylinder) is equal. So move z. B. the piston of the piston pair 16a . 16b with a rotation of the double cam 18 according to the arrow from their shown middle positions respectively further into their cylinders 6a . 6b into it, resulting from this pair of pistons 16a . 16b Pressure medium compressed and from the cylinder pair 6a . 6b is displaced. This synchronization according to the invention of two opposite cylinder-piston units, it is possible to apply their two high-pressure valves and their two low-pressure valves at each operating time of the radial piston pump with the same control signal. Thus, according to the invention, only four low-pressure side power amplifiers 22 and four high-pressure side power amplifiers provided. This results in a halving of the total 16 Output stages, which are necessary in a comparable radial piston pump according to the prior art.

2 shows a second embodiment of a radial piston pump according to the invention in a schematic representation. The cylinder body with the cylinders and the piston guided therein including the double cam according to the invention correspond to those of the first embodiment according to 1 , The essential difference of the second embodiment from the first embodiment is to be seen in the fact that according to the invention not only the number of output stages, but also the number of valves over the prior art are halved. This reduction of the valves is exemplified by the low pressure side of the cylinder pair 2a . 2 B explained. At every cylinder 2a . 2 B is a low pressure line 126a . 126b connected to a common low pressure line 126 lead. Between the low pressure line 126 and the low pressure port ND of the radial piston pump is a common low pressure valve 120 arranged, whose operation with that of the first embodiment according to 1 essentially coincides. However, the low pressure valve 120 for (compared to the low pressure valves 20a . 20b ) doubled volume flows designed because of the low pressure valve 120 the pressure medium to both cylinders 2a . 2 B has to flow.

At the lifting magnet 128 of the low pressure valve 120 is via a control signal line 124 an amplifier 122 connected, whereby also the lifting magnet, the line 124 and the power amp 122 designed for increased performance.

at this embodiment of the invention Radial piston pump is compared to a comparable radial piston pump According to the prior art, the number of Power amplifiers reduced from 16 to 8, reducing the device-technical Effort for the electrical system is significantly reduced.

3 shows a diagram in which the flow rate V. _{Valve of} a low pressure _valve of a Radi piston pump (DDU), which according to the prior art has a cam portion over which time is shown. This low-pressure valve is open for approximately half the duration of one revolution of the drive shaft, wherein the volume flow V. _Valve simplified during this time is assumed to be constant. The illustrated thus rectangular area gives the sucked by the associated individual piston volume.

at an embodiment of the invention (not shown) Radial piston engine is the cylinder capacity to 1 / [number the cam sections] compared to a comparable machine with a cam portion (according to the prior art Technology). The delivery or intake volume remains the machine unchanged. For example, with three cam sections The displacement of the cylinder can be reduced to 1/3. This is the result Diameter of the machine and thus reduced their space.

4 shows a diagram in which the flow rate V. _{Valve of} a low pressure _valve of such a radial piston pump (DDU), their displacements over those from 3 are halved by way of example, is shown. In this case, a double cam and in pairs hydraulically combined cylinders are provided accordingly. Due to the double cam, the associated pair of pistons performs two work cycles during one revolution of the drive shaft or the double cam, wherein the volume of both cylinders must be supplied synchronously during each downstroke. This doubles, as can be seen from a comparison of 3 and 4 can take, the volume flow V. _{Valve that} flows through each low-pressure _valve . The delivery volume of this embodiment is unchanged, since the doubling of the power strokes per revolution is compensated by halving and the displacement.

at another (not shown) embodiment or Operating state is the speed of the lift curve to 1 / [number of Cam sections] compared to a comparable machine reduced with a cam portion. This also remains Delivery or absorption volume of the machine unchanged. For example, with four cam sections, the speed of the lift curve reduced to 1/4. Thereby the requirements to the Switching speed of the valves reduced.

5 shows a diagram in which the flow rate V. _{Valve of} a low pressure _valve of such a radial piston pump (DDU), whose speed compared to those 3 is halved by way of example, is shown. Accordingly, a double cam and pair hydraulically combined cylinders are provided. Thus, the halving of the supply periods, which arises in principle by the double cam, compensated, so that the supply of each individual cylinder comparable to that of the prior art according to 3 runs. By merging two low-pressure valves to form a low-pressure valve (cf. 2 ) is the volume flow V. _{Valve of} the cylinder pair, which flows through the low-pressure _valve doubles.

at a further (not shown) embodiment of the Radial piston engine according to the invention is the Number of cylinder-piston units to 1 / [number of cam sections] compared to a comparable machine with a cam portion reduced. At the same time, the delivery or absorption volume remains the machine unchanged. For example, with three cam sections the number of cylinder-piston units including valves reduced to 1/3 become. As a result, the production cost of the machine is reduced.

deviant of the embodiments shown and described can Radialkoibenmaschine invention also be a radial piston engine.

Farther the lift curve may deviate from the embodiments shown also have more than two cam sections.

The Lifting curve with more than one cam can also be on the inner circumference of a be arranged rotatable cam ring, with the Ab- or drive shaft the valve-controlled radial piston machine according to the invention connected is. Here, the standing cylinder body is corresponding arranged in the interior of the cam ring and the rollers of the piston according to directed outside.

Disclosed is a valve-controlled radial piston engine with at least two Cylinder-piston units, electronically controlled by power amplifiers High-pressure and low-pressure valves are assigned, and with a rotatable lift curve, at which the pistons were supported. The lift curve according to the invention has at least two Cam portions.

at a particularly preferred embodiment of the invention Radial piston engine is the number of high-pressure side Output stages and / or the low-pressure end stages in each case [number cylinder-piston units] / [number of cam sections].

1

cylinder body

2a, 2 B

cylinder

4a, 4b

cylinder

5a, 5b

cylinder

6a, 6b

cylinder

12a, 12b

piston

14a, 14b

piston

15a, 15b

piston

16a, 16b

piston

18

double cam

18a, 18b

cam section

20a, 20b

Low-pressure valve

22

final stage

24a, 24b

Control signal line

28a, 28b

solenoid

126a, 126b

Low-pressure line

120

Low-pressure valve

126

common Low-pressure line

124

Control signal line

122

final stage

128

solenoid

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - WO 2006/109079 A1 [0004]

Claims (10)

Radial piston machine with at least two cylinder-piston units, which from high-pressure side power amplifiers electrically or electro-hydraulically controllable high-pressure valves and / or low-pressure side power amplifiers ( 22 ; 122 ) electrically or electro-hydraulically controllable low-pressure valves ( 20a . 20b ; 122 ) and with a rotatable lift curve ( 18 ) on which the pistons are supported, characterized in that the lifting curve ( 18 ) at least two cam sections ( 18a . 18b ) Has. Radial piston machine according to claim 1, wherein the cylinder-piston units uniformly on the circumference of a cylinder body ( 1 ) and the cam sections ( 18a . 18b ) evenly at the circumference of the lift curve ( 18 ) are distributed. Radial-piston machine according to claim 1 or 2, wherein the number of high-pressure-side output stages and / or the number of low-pressure-side output stages ( 22 ; 122 ) is [number of cylinder-piston units] / [number of cam sections]. A radial piston machine according to claim 3, wherein high-pressure valves are provided through each high-pressure side output stage [number of cylinder-piston units] / [number of high-pressure-side output stages], and / or through each low-pressure side output stage ( 22 ) [Number of cylinder-piston units] / [number of low-pressure-side output stages] low-pressure valves ( 20a . 20b ) are controllable. Radial-piston machine according to claim 3, wherein the number of high-pressure valves corresponds to the number of high-pressure-side output stages, and / or wherein the number of low-pressure valves ( 120 ) the number of low-pressure end stages ( 122 ), and wherein each high-pressure valve and / or each low-pressure valve ( 120 ) over n hydraulic lines with n cylinders ( 2a . 2 B ), where n is the number of cam sections ( 18a . 18b ). Radial piston machine according to one of the preceding claims, wherein the lifting curve ( 18 ) with the cam sections ( 18a . 18b ) is formed on the outer periphery of an eccentric shaft. Radial piston machine according to one of the claims 1 to 5 , wherein the lifting cam is formed with the cam portions on the inner circumference of a cam ring. Radial piston machine according to claim 4 and 6, which is a radial piston pump with eight cylinder-piston units, two cam sections ( 18a . 18b ), four high-pressure-side output stages and four low-pressure-side output stages ( 22 ), wherein each cylinder-piston unit is a high-pressure valve and a low-pressure valve ( 20a . 20b ) assigned. Radial piston machine according to claim 5 and 6, which is a radial piston pump with eight cylinder-piston units, two cam sections ( 18a . 18b ), four high-pressure-side output stages and four low-pressure-side output stages ( 122 ), each high-pressure side end stage being a high-pressure valve and each low-pressure end stage ( 122 ) a low pressure valve ( 120 ) and wherein each high-pressure valve and each low-pressure valve ( 120 ) via two hydraulic lines ( 126a . 126b ) with two opposing cylinders ( 2a . 2 B ) connected is. Radial piston machine according to one of the preceding claims, wherein each high-pressure valve and / or each low-pressure valve, a 2/2-way valve ( 20a . 20b . 120 ), whose valve body has a spring-biased shut-off position and one of the corresponding output stage ( 22 ; 122 ) has activatable passage position.