EP1411245A1 - Hydraulic piston machine - Google Patents

Abstract

The hydraulic piston pump has one or more cylinders (23), each with an impeller piston (1). The cylinders have an inflow (13) and an outflow (17) valve, and a spring zone (16). A control roller (3,) to set the pumping volume, is operated by the drive shaft (8) and has an axial sliding movement. A control edge (4) is at the roller circumference with a structure so that, according to the axial position, a bypass drilling (15) in the cylinder is closed or during a pump impelling cycle it is wholly or partially cleared.

Description

The invention relates to a hydraulic piston machine comprising one or more cylinders with guided therein Delivery piston, the cylinders one on and one Have an outlet valve and an element space, comprising a flow control and a drive shaft to control the delivery pistons.

State of the art

Such hydraulic piston machines are known, for example. from DE 199 54 639 A1, which is a hydraulic piston pump discloses, in particular for common rail injection systems, the piston pump being one or more axially or radially has arranged cylinders that are ring-shaped or star-shaped are arranged and a flow control over the Piston located oblique control edges. Here is provided the pistons of all cylinders simultaneously and in to twist in the same way, the flow rate adjusting sloping control edges on the front of the Pistons are arranged. About the rotation of the pistons can then the available injection volume in the Element space can be varied. Depending on whether over the Control edge the inlet bore is closed or open, can be a zero or a full funding or each intermediate delivery rate can be set.

A disadvantage of the prior art is that the different pistons laboriously related to each other Twisting motion must be synchronized and one Twisting movement of many parts is necessary. such Systems are prone to wear.

Furthermore, US Pat. No. 5,603,609 is a Axial piston pump known in which the drive of the piston likewise as in DE 199 54 639 A1 via a Swashplate drive takes place. It is provided here controlling the amount of injection by the pistons High pressure is brought to regulate by means of sliders Passages in the individual cylinders completely or partially close or open. As with the The aforementioned prior art consists of Disadvantage that all sliders are controlled separately must, which means an increased control effort and a higher probability of error arises.

The object of the present invention is now a hydraulic piston machine of the above Provide described type in which a Demand control is easy to implement that only a little effort with regard to the to be controlled and which has moving parts.

The invention solves this problem by a hydraulic Piston machine comprising one or more cylinders conveying pistons guided therein, the cylinders being a single and have an outlet valve and an element space, comprising a flow control and a drive shaft to control the delivery piston, a control roller is provided, which is driven via the drive shaft and is displaceable in the axial direction, the Control roller has a control edge on its circumference, the has such a course that depending on the axial Position of the control roller has a bypass hole in the closes at least one cylinder or during one Delivery cycle of the delivery piston in whole or in part releases time.

Advantages of the invention

The invention has the advantage that due to a especially centered between the star or ring arranged cylinders provided individual control roller all pistons or cylinders are controlled simultaneously can. The control edge is designed so that it is enables for all assigned cylinders, in time Course over a conveying cycle, i.e. one stroke and one Suction phase of the delivery piston, which is usually one Rotation of the drive shaft corresponds to a bypass hole, the one in the cylinder next to the inlet and outlet bore is provided, completely or only during part of the funding cycle. Alternatively, the opening can also be completely released. In particular, the bypass hole is opened when only partial funding is to take place during the Piston stroke phase. Here is the remaining stroke of the delivery piston after completely closed Cross section of the bypass hole determining for itself adjusting delivery rate of the cylinder.

About the choice of the shape and the course of the control edge can the characteristic of the closing process of the bypass hole be determined, creating a low pulsation edge-controlled demand control can be realized.

In a first exemplary embodiment, that the control of the delivery pistons via a with the Swash plate connected to the drive shaft. Conceivable However, other hydraulic piston machines are also available non-rotating cylinders. I.e. the cylinders are stationary relative to the housing.

The cylinders can be aligned axially, i. H. their longitudinal extent or the longitudinal axis of the cylinders runs in the direction of the drive axis or in Direction of the control roller axis. That way is a The individual pistons are particularly easy to drive realize. Alternatively, however, is also according to the invention possible to use a radial piston pump in which the Pistons and cylinders are arranged in a star shape and radial point outwards. The individual cylinders controlled one after the other by the control edge constant axial displacement, the control with the control especially of the pistons via z. B. the Swashplate is synchronized.

In particular, it can be provided that the control edge at maximum delivery rate, i.e. full funding, the Bypass drilling during the entire production cycle, closes especially during the stroke phase of the piston.

During zero funding, i.e. H. it won't be fuel or other hydraulic fluid through the piston conveyed, the control roller is axially displaced in such a way that during the entire rotation of the control roller the Control edge fully or partially clears the bypass hole.

Finally, partial funding can be provided, whereby the control edge is designed so that it is in the course the lifting phase from a closed to an open Bypass opening can be adjusted by turning the Control roller. For this purpose, a so-called oblique can be provided Control edge to be provided so that by the rotation of the First control roller completely or partially the bypass hole is open and then in the course of the further rotation is closed in whole or in part. The control edge runs thereby around the entire circumference of the control roller.

It can in particular be provided that the Closing the bypass opening continuously done, d. that is, no sudden jumps like a sudden closure of the bypass hole made become.

About the extent and the slope that the bevel of the Has control edge, the demand control can continue can be varied.

The axial displacement of the control roller can, for example a proportional magnet or a piezo actuator. The position of the control edge can be relative to Bypass bore over the current strength of the Proportional magnets or the actuator voltage of the piezo actuator can be set. For example, a very high voltage is applied created the piezo actuator, it expands as a result of Tension off and the movement can be coupled or uncoupled and / or reinforced on the control roller be transmitted. This is done in an analogous manner via the Setting the current level for the Proportional solenoid.

It can be provided that the control roller with the Drive shaft is directly coupled, d. H. that per Revolution of the drive roller one revolution of the control roller he follows.

The control for any number of pistons over a single one Control element, namely the control roller possible. To this Way, a significant reduction in parts and thus Cost savings especially when implementing a Volume flow control with multi-cylinder pumps.

drawing

Figur 1

eine erfindungsgemäße hydraulische Kolbenmaschine in einer Stellung der Steuerwalze zur Vollförderung;

Figur 2

die Kolbenmaschine gemäß Figur 1 in einem Teilförderbetrieb;

Figur 3

die Kolbenmaschine gemäß Figur 1 in einem Nullförderbetrieb;

Figur 4

ein weiteres Ausführungsbeispiel der Erfindung in Form einer Konstantdruckpumpe.

The invention will be explained in more detail below with reference to a drawing. Show:

Figure 1

a hydraulic piston machine according to the invention in a position of the control roller for full delivery;

Figure 2

the piston machine according to Figure 1 in a partial conveyor operation;

Figure 3

the piston machine according to Figure 1 in a zero delivery mode;

Figure 4

a further embodiment of the invention in the form of a constant pressure pump.

Figure 1 shows a piston machine according to the invention in de-energized state. The piston machine includes several delivery pistons, which are designated by 1. The Delivery pistons 1 are arranged in cylinders 23 and therein rotationally fixed to the housing 2. The drive of the Delivery piston 1 takes place via a drive shaft 8, the Delivery piston 1 with the drive shaft 8 via a Swashplate 7 are connected and in axial Direction are arranged. Do the one shown Piston machine on the drive shaft 8, so the Rotation via the swash plate 7 on sliding shoes 12 transmitted, whereby an axial movement of the delivery piston 1st depending on the position of the swash plate 7 in the image direction to the right or to the left in the direction of the image. This allows a stroke and a suction movement of the piston 1 can be achieved.

At the beginning of a delivery stroke, this includes Inlet valve 13 of the piston, through which this with a Hydraulic fluid reservoir communicates, particularly with a fuel reservoir, provided the piston engine is used in a common rail system, for example. About the Rotation of the drive shaft 8 takes place Swashplate and the movement of the piston 1 is a Element space 16 pressurized. Is the final pressure reached, an outlet valve 17 opens and the Piston displaced medium is in an annular space 18r promoted from where it is connected to a Consumers, especially a common rail module is forwarded.

On the return stroke of the delivery piston 1, the outlet valve closes 17 again and via the inlet valve, new medium is expelled a reservoir, for example an engine room 18.

Centrally and also arranged in the axial direction is surrounded by the delivery piston 1 Control roller 3, which has a control edge 4. The Control roller 3 is with the drive shaft 8 via a Driving pin 5, which engages in a groove 6, with the Swash plate 7 connected and is driven thereby. This ensures that the swashplate 7 and turn the control roller 3 at the same speed and the angular position of the control edge 4 relative to the piston stroke is fixed. That is, an angular position of the control edge 4 a specific piston stroke is always assigned. The Control roller 3 can be moved axially. For this is in Area of the swash plate 7 on the swash plate supporting spring 9 is provided which the control roller 3 in axial direction - to the right in FIG. 1 - against one Tappet 10 of a fixed proportional magnet 11 suppressed.

Is now a full funding, as shown in Figure 1, so maximum delivery by the piston machine is desired, so the proportional magnet 11 remains de-energized, whereby the Control roller in the far right shown in the picture Position comes to lie. The control edge 4 is so designed that they are not in this de-energized state protrudes into the area of a bypass bore 15, which Element space 16 with the roller 3 and a roller groove 19 and connects to the engine room 18. Much more closes the control roller 3 in this position Bypass hole 15 completely. That is, everything through The medium that flows into the inlet valve is in the element space 16 compressed and through the exhaust valve into the system injected. The tax cross section 14, the Outlet opening of the bypass opening 15 in the area of Control roller 3 corresponds, remains here over the entire Delivery cycle, the one rotation of the swash plate 7th corresponds, closed.

Figure 2 shows the piston machine according to Figure 1 in one Partial funding operation. For this, the Proportional magnet 11 energized such that the plunger 10 moved to the left in the picture and onto the control roller 3 acts and this against the force of the spring 9 in the picture also shifted to the left. This will in one first position shown here of the drive shaft 8 and so that the control roller 3 released the bypass bore 15. In the illustrated embodiment, the Current intensity of the proportional magnet 11 in this way set that the control edge 4 partially on the in the left side of the bypass bore 15 in the image plane comes, whereby the bypass bore 15 is completely released becomes. Any of the current levels can Position of the roller 3 with the control edge 4 relative to Bypass bore 15 can be set. In Figure 2 the Proportional magnet 11 shown in a central position. At the start of the stroke, which is shown in FIG. 2, the Bypass hole fully opened. With increasing stroke and thus increasing rotation of the drive shaft 8 and thereby the control roller 3 closes the discharge cross section 14 of the bypass bore 15 due to the in the axial direction sloping control edge 4. This ensures that that 1 medium so during the stroke phase of the delivery piston long over the discharge cross section 14 and through the Roll groove 19 via a return bore 20 in the Engine room 18 flows back until the roller 3 over the Control edge 4, the discharge cross section 14 completely closes.

As soon as the bypass bore 15 is completely closed, the delivery phase of the piston machine begins. The Exhaust valve 17 is then opened and the rest Stroke volume from the delivery piston 1 is in the annular space 18 in promoted in the manner described above. It can be from forwarded from here to connected consumers become.

The control edge 4 is designed so that it is too a continuously increasing closure of the Bypass bore 15 during the rotation of the control roller 3 comes. This allows a particularly low-pulsation Demand control can be realized.

Finally, FIG. 3 shows the piston machine according to FIG. 1 in a zero funding mode. Here is the proportional magnet 11 is energized to the maximum, so that the Ram 10 in its maximum position in the Drawing level has moved to the left. The roller 3 will further reinforced against the spring force 9 in the Drawing layer moved to the left until it with the Driving pin 5 rests in a groove base 21 of the groove 6. The Roller 3 is so far shifted that when entire control cycle the control edge 4 always in the Image plane to the left of the bypass hole opening, namely the Discharge cross section 14 remains. Closing the Discharge cross section 14 takes place throughout Funding cycle does not take place. As a result, during the conveying stroke no pressure can be built up in element space 16, since that total displacement of the delivery piston 1 over the Bypass bore 15, the roller groove 19 and the return bore 20 flows back into the engine room 18. During the suction stroke of the Delivery piston 1, i.e. the second part of the delivery cycle, the element space 16 via the inlet valve 13 and via the above-mentioned control path, namely the Return bore, the roller groove and the bypass bore again filled with medium.

A pressure build-up does not take place in this state.

The piston machine shown in FIGS. 1-3 bounces with partial or zero funding, the discharge jet of the Medium that emerges from the discharge cross section 14 the inclined end face of the roller 3. From this results in an axial force component that acts against the Spring force of the spring 9 of the control roller 3 acts. Here is the inflow of those adjacent to the control edge 4 End face of the roller 3 via the bypass bore 15 crucial for the resulting on the roller 3 Flow forces. About the shape and location of the bypass hole 15 and flat surface of the control roller 3 can be the affect hydraulic roller forces.

To prevent wear between the rotating control roller 3 and the standing plunger 10 of the proportional magnet 11 avoid, can also be provided the control roller 3 and to produce the plunger 10 in one piece. The Ram 10 rotates with the control roller 3. Ram 10 and Armature 22 circulate in the stationary coil body. The This can reduce wear.

Finally, Figure 4 shows another alternative Design of the piston machine according to the invention FIGS. 1-3. The control roller 3 is used here shown with a constant pressure pump. In this case the proportional magnet 11, which in FIGS. 1-3 is shown, replaced by a piston assembly 28, a piston 27 directly with the control roller 3 is connected and wherein a seal Abstellraumes 30, over the zero or partial funding Fluid can flow back into the engine room 18 from a piston chamber 25 takes place. The piston 27 is over a piston seal 24 is provided as a separator. The Piston chamber 25 is a transverse bore 26 which with a Annulus 29 is connected, filled and emptied. Is lying in Annulus 29 no pressure, so the spring 9 pushes the roller 3 to the far right in the figure. This corresponds to the Roll position according to FIG. 1. The discharge cross section 14 the bypass bore 15 remains closed. The Piston machine works with full delivery. With increasing Pressure in the annular space 29, the on the transverse bore 26 the piston 27 acts, the roller 3 against the force of Spring 9 shifted to the left in the image plane, that the area of partial funding is reached. A Displacement continues until the spring force of the Spring 9 and the pressure in the piston chamber 25 against each other pick up and balance. About the vote the spring preload and the piston surface can be hereby set any pressure that is different from the Piston engine is kept constant. That way the proportional magnet or another is particularly simple Actuator to shift the roller 3 to be replaced. The Annulus 29 can communicate with annulus 18r.

Further advantages and features of the invention result from the other application documents, which are characteristics individually and in any combination with each other essential for the invention.

Claims (11)

Hydraulic piston machine, comprising one or more cylinders (23) with a delivery piston (1) guided therein, the cylinders (23) having an inlet (13) and an outlet valve (17) as well as an element chamber (16) and with a delivery rate control and Drive shaft (8) for controlling the delivery pistons (1), characterized in that a control roller (3) is provided which is driven by the drive shaft (8) and is displaceable in the axial direction, the control roller (3) having a control edge on its circumference (4), which has such a course that, depending on the axial position of the control roller (3), a bypass bore (15) is closed in the cylinders (23) or is completely or partially released in time during a delivery cycle of the delivery piston (1). Hydraulic piston machine according to claim 1, characterized in that the delivery pistons (1) are actuated via a swash plate (7) connected to the drive shaft (8). Hydraulic piston machine according to claim 1 or 2, characterized in that the cylinders (23) are arranged axially and they run radially spaced around the control roller (3), which is arranged particularly centrally. Hydraulic piston machine according to one of claims 1 to 3, characterized in that the control edge (4) closes the bypass bore (15) during the entire delivery cycle at the maximum delivery rate. Hydraulic piston machine according to one of claims 1 to 4, characterized in that the control edge (4) at least partially releases the bypass bore (15) when a partial quantity is conveyed at the beginning of the delivery cycle and in the course of a stroke phase of the delivery piston (1) in the delivery cycle depending on the delivery quantity the bypass bore (15) closes due to the rotation of the control roller (3) relative to the cylinder (23). Hydraulic piston machine according to one of claims 1 to 5, characterized in that the control edge (4) at zero delivery at least partially clears the bypass bore (15) during the entire delivery cycle. Hydraulic piston machine according to one of claims 1 to 6, characterized in that the control edge (4) has a continuous, bevelled course and the bypass bore (15) continuously closes during partial conveyance. Hydraulic piston machine according to one of claims 1 to 7, characterized in that the axial displacement of the control roller is realized via a proportional magnet or a piezo actuator. Hydraulic piston machine according to claim 8, characterized in that the position of the control edge (4) relative to the bypass bore (15) is adjustable via the current intensity of the proportional magnet (11) or the actuator voltage of the piezo actuator. Hydraulic piston machine according to one of claims 1 to 7, characterized in that the displacement of the control roller (3) takes place via a piston which is acted upon by a hydraulic medium. Hydraulic piston machine according to one of claims 1 to 10, characterized in that the control roller (3) is directly coupled to the drive shaft (8).

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