DE1908931C3 - Device for adjusting the delivery rate of a radial piston pump - Google Patents

Description

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The invention relates to a device for adjusting the delivery rate of a drive shaft Drivable radial piston pump with an annular, circumferential pump piston actuating the pump piston Eccentric, which is radially displaceable depending on the with respect to its direction of rotation Piston of a rotating servomotor acting pump delivery pressure in a concentric and dependent manner a spring force acting on the piston can be adjusted into an eccentric end position.

A pump with pistons arranged in a star shape in a cylinder block has already become known (DT-AS 1 101 961), the cylinder block around a stationary, the piston actuating and for purposes the change in stroke of the pistons as a function of the pump pressure on the pressure side and an adjustable one Spring adjustable eccentric pin revolves. The fixed eccentric pin is only to change the eccentricity radially movable in such a way that the resultant of all piston forces is perpendicular acts on the direction of adjustment and therefore the movable

chen eccentric cannot be adjusted.

In another known piston pump (CH-PS 204 332) with a delivery rate that depends on the delivery pressure and the final pressure is adjustable via a spring when the working piston has finished its idle travel and the .feed pressure begins to rise that of the Pump piston triggered moment overcome the moment of the spring and the eccentric in its concentric Turn back position. Apart from the fact that no special reset device is provided here is and so no precisely determinable feedback is possible, the pump piston resistance is not to Used to return to the eccentric position.

Finally, in the case of the setting device (US Pat. No. 2,404,175) on which the invention is based, an adjustable Ultimate pressure cannot be achieved because the annular eccentric is arranged on the drive shaft via springs is and returned to its concentric position via the piston which is displaceable in the drive shaft can be. The overall structure is complex due to the arrangement of the eccentric via springs and an exact and controlled adjustment of the eccentric cannot be achieved.

Which the object underlying the invention is seen to provide an apparatus of the initially named \ t to create \ in which the eccentric is mounted on the drive shaft such that the drag forces caused by the pump piston move the eccentric in its eccentric position. This object has been achieved in that the drive shaft is provided with a shaft connector which is arranged eccentrically on its central axis and which accommodates the annular eccentric rotatably eccentrically to its longitudinal central axis, the eccentric being provided with a centrally arranged pin on which the piston of the servomotor attacks. In this way, in addition to the spring moment, the moments occurring on the pump piston can contribute to shifting the eccentric into its position of greatest eccentricity. As a result, a smaller dimensioned spring can be used, so that a better dosage is possible. Overall, a structurally simple servomotor is created for such pumps, which can be pressurized from the pressure side of the pump and whose embodiment allows a non-rotating adjustment option for the rotating spring to be created with simple means.

So that the servomotor can be driven from the drive shaft, the shaft connector engages a hole provided in the servomotor.

As far as the adjustment option for the spring is concerned, the connection between the piston and the is centric on the eccentric pin provided a rod connected to the piston is provided with an opening, which runs inclined with respect to the servomotor axis of rotation and a correspondingly designed, manually and receives her movable sleeve which in turn slidably receives the pin.

The piston on its side remote from the rod with the delivery pressure of the pump is advantageous and on its side facing the rod can be acted upon by the spring force, the sleeve via a adjusting screw resting against one of its radial sides and arranged in the axis of rotation of the servomotor is axially adjustable against the action of a spring.

in the drawing is an embodiment of the explained in more detail in the following description

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Subject of the invention shown It shows F i g. 1 the pump in longitudinal section,

F i g. 2 shows a section along the line 2-2 in FIG. 1.

F i g. 3 the eccentric in cross section

In Fig. 1 of the drawing, 2 denotes a pump with a pump housing 3 and a cover 4 A The pump room 5 provided in the pump housing is through the ceiling! 4 locked. A cylinder arranged radially 6 is incorporated into the pump housing 3

Seal 29 prevents leakage oil losses. Another channel 31 in the housing 14 is used to connect the Pressure chamber 30 with the closed end of the bore 22. Thus, pressure fluid can from the Dnjckseite the pump reach the piston 23 and move the rod against the action of the spring 26.

The rod 24 itself has an opening 32 which is angled with respect to the axis of rotation of the housing 14 and a sleeve 33 slidably on-

and open to the pump chamber 5. The drawing shows io, the surface of which is similarly angled

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only a single cylinder is shown, although several distributed on the circumference cylinders are provided. The latter have not drawn suction and Pressure valves open. A piston 7 is axial in the cylinder 6

The sleeve 33 is provided with a central bore 34, which runs parallel to the axis of rotation of the housing 14 and receives the pin 19. This one is like already was carried out, provided on the eccentric and

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displaceably guided. A spring 8 rests against the outer 15 through an opening provided in the bore 22

ßere closed end of the cylinder 6 and guided against the assumption that the shaft inner end of the piston 7 at. A drive shaft 9 is
stored in the pump housing 3 via a bearing »0, whose

mel 19 is arranged in the sleeve 33, the eccentric 17 can about the nercs u .. _uc UU..M v ...... ^ ... ". κ, <". . "," ,,. ^ "« U. Shaft connector 12 in the area between its eccentric

provided annular flange 11 is limited. See at last ao and adjusted its concentric end position

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inner end through a also in the pump housing h Riflh 11 bt it A ltt

A shaft connector 12 (FIG. 2) with reference to FIG Drive shaft 9 arranged eccentrically. This extends after seen from the annular flange 11 front to a hole 13, which in turn in a

Servomotor housing 14 is incorporated. The servomotor 35 would have to be.

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will. By axial displacement of the sleeve 33 in and out of the opening 32, the effective force of the spring 26 can be varied. The spring can be tensioned or relaxed without changing the position of the eccentric

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housing 14 in turn has a bearing shaft 15 which is mounted in the pump cover 4 via a bearing 16 so that the housing with the drive shaft 9 rotate can.

Em eccentric 17 is on the shaft connector 12 between the annular flange 11 and the housing 14 eccentrically arranged and for this purpose provided with a bore 18 (FIG. 3). The latter is off-center with respect to the central axis of the eccentric arranged so that the

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As far as the construction for adjusting the sleeve 33 is concerned, an adjusting screw 36 is provided which concentrically to the axis of rotation of the housing 14 can be screwed into the pump housing 3 and continues through the Pressure chamber 30 is guided into a bore 37 of smaller diameter, which the pressure chamber 30 with the bore 22 connects and a pin 38 were slidable. The latter rests against the adjusting screw 36 at one end and is at the other end with a disk-like end

Ex / enter, when it rotates around the shaft stub 12, provided from ₃₅ 39, which in turn rests against the sleeve 33 in order to achieve a position which, with respect to the drive shaft, makes it move in one direction ^ 8 ^Γεηζεη ; ® ™ 9 is concentric, can be pivoted into an eccentric end position with respect to the drive shaft

can. A pin 19 engaging in the center of the eccentric

disc shaped end 39 is intended to maintain contact with the sleeve when the rod 24 is in the bore

can, tin miuig am nxs.ciucr angicucuuci «μκ-ι, _i3 22 is axially displaced. The sleeve 33 extends forward from the eccentric to ₄₀ opening 32 against the end of the pin 38 via a into the housing 14 and an outer race 21, and against the housing 33 via a spring 41, against which in turn the inner ends of the KoI- is pressed. This is in a pre-set in the eccentric 17 7 applied. This reduces wear. The bore 42 shown is arranged and is located at one end. A bore ₄₅ is also machined into the servomotor housing 14 against the plunger 40 and at the other end against a 22 which is attached to the spring-receiving cap 43 from the periphery. If the adjusting the central axis is now screwed out of the cover 4 to a point in the vicinity of the screw 36, the opposite periphery extends and the provided spring 41 acts together with the adjusting piston 23 and accommodates it in a displaceable manner Pin 38 of the position of a rod 24 engaging at its inner end with ₅₀ screw 36 follow. If the adjusting screw is screwed in in the Dekrectangular cross-section and an annular angle 4, the spring 41 is tensioned because the end part 25 opens. The latter is provided at the end where the piston is held down, the sleeve 33 pushes the plunger 40 into the pin 19 and rests against the cylinder. Since the adjusting screw is provided in the axis of rotation of the drapery of the bore around the rod in the rear housing 14, the sleeve can be guided during working and forward movement. The piston 23 itself 55 of the pump or also before the pump is actuated.

is pressed by a spring 26 in the direction of the closed end of the bore 22. The spring is there at one end against the annular end part 25, at the other end against a plug 27, which the open The end of the bore 22 closes

A line, not shown in the drawing for the sake of simplicity, also connects the pressure side a channel 28. The latter is incorporated in the pump cover 4 and opens into a small pressure chamber 30,

adjusted.

When using the pump described above and provided that internal forces and Neglecting friction, there are three essential- o before torques that contribute to the eccentric to adjust the shaft connector 12. The first of these torques is from the spring 26 Moment that acts on the pin 19 and helps to increase the eccentricity of the eccentric 17.

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65 This torque is inversely proportional to the

angle 4 and in the bearing shaft 15 of the servomotor housing value of the eccentricity of the eccentric 17, and if the

14 was formed. The pressure chamber 30 is coaxial with the maximum eccentricity of the eccentric 17 at a relative

The axis of rotation of the housing 14 is arranged whereby a tiv small value is limited, this torque is

essentially linear to the value of the eccentricity of the Eccentric run.

The second torque tends to rotate the eccentric 17 also around the shaft connector 12 and is a torque resulting from the pressure diverted from the pressure side and on the trunnion 19 is transmitted via the piston 23. This torque tends to decrease the eccentricity of the eccentric 17, and when the maximum eccentricity of the eccentric 17 is limited to a relatively small value, this torque is essentially be directly proportional to the pressure on the pressure side.

The third torque depends on the load and is determined by the pressure on the pressure side of the pump and opposes the outward movement of the piston 7. This torque is directly proportional to the product of the pump pressure on the pressure side and the value of the eccentricity of the Eccentric 17. When the pump now rotates counterclockwise, with reference to F i g. 2. rotates, ao this torque contributes to increasing the eccentricity of the eccentric 17.

The usable torque, which tends to rotate the eccentric 17 around the shaft connector 12, is the algebraic sum of the torques which are dependent on the spring, the pressure and the load. If now the spring force is chosen so that. when the amount of eccentricity of the eccentric changes, the torque from the spring increases or decreases in direct proportion to and to the same extent as the increase or decrease in the torque of the load, and when the initial torque from the spring is about corresponds to the torque of the pressure side, the usable torque, which tends to rotate the eccentric 17 about the shaft connector 12, will be approximately zero when the pump is operating at the intended pressure. If, however, the pump works at a lower pressure than the previously determined pressure, the usable torque tends to increase the eccentricity of the eccentric 17. If the pressure is greater than the previously determined pump pressure, the usable torque causes a reduction in the eccentricity of the eccentric 17.

In order to be able to imagine the mode of operation more simply, the torque originating from the spring and the torque originating from the load are combined into a single torque which tends to move the eccentric 17 into its end position, in which it has the greatest eccentricity. And if one assumes that this single torque comes from the force exerted by the spring 26 on the pin 19, then the operation of the pump described above can be summarized as follows:

Before the pump is activated, the spring 26 will force the rod 24 ir. Moved to the position shown in the drawing, in which the eccentric is in its end position with the greatest eccentricity. During use, the drive shaft 9 is now driven by a motor or the like. A rotation of the shaft, however, causes a rotation of the housing 14 and the eccentric 17 at the same time, so that the eccentric pushes the piston 7 radially outwards move the pump housing 3. The resulting suction stroke of the piston causes pressure fluid to be sucked through the suction valve into the cylinder. If the eccentric now continues to rotate, it will in turn cause a radially outward movement of the piston 7, and the pressure medium located in the cylinder 6 is pressed through the pressure valve into the pressure line. Thus, a pressure will build up on the pressure side of the pump, which via the line or the channel that connects the pressure side with the channel 28, the channel 28, the pressure chamber 30 and the channel 31 to the closed end of the bore 22 will propagate where it acts on the piston 23. The pressure then acting on the piston 23 moves it together with the rod 24 against the action of the spring 26, the latter being tensioned and the eccentric being adjusted around the shaft connector 12 into its end position, in which it is arranged concentrically to the drive shaft. If, however, the eccentric 17 is moved into its concentric end position, the stroke of the piston 7 is reduced, since the eccentric can no longer move the piston radially outward as far and the pistons can no longer enter the pump housing as far inward as it was possible with greater eccentricity. The shortened piston stroke in turn results in a lower fluid throughput on the pressure side.

As soon as the liquid pressure on the pressure side has reached a previously determined maximum value. the pressure prevailing on the pressure side will have displaced the rod 24 so far that the eccentric has been displaced into a position which is concentric with respect to the drive shaft 12. If the eccentric is now in its concentric end position, the pistons 7 stand still and no additional liquid can be conveyed into the pressure line, even if the eccentric continues to rotate. The pump will remain in this state until the pressure on the pressure side drops again.

If the hydraulic system, which is supplied with pressure medium from the pump, also requires pressure fluid, the pressure on the pressure side will drop to a value below the previously determined value. At the same time , however, the liquid pressure which acts on the piston 23 will also drop. A drop in this pressure in turn causes the spring 26 to displace the rod so that the eccentric can now move the shaft seal 12 into its end position with the greatest eccentricity. The movement of the rod and the eccentricity of the piston, which are just allowed by the eccentric, depend on the size of the pressure drop on the pressure side. If, however, the eccentric is again in its end position with the greatest eccentricity, the piston stroke becomes larger and more liquid reaches the pressure line, whereby the liquid pressure in the pressure line again rises to the previously determined maximum value.

For the sake of completeness, it must be pointed out that the above description of the mode of operation only applies if the eccentric rotates counterclockwise, with reference to F 1 g. 2. Is swiveled If the pump is clockwise / counterclockwise. namely also with reference to aul F i g. 2, the position of the eccentric 17 is rotated under the control of the torques, as was explained above, since the torque resulting from the load then does not contribute to reducing the eccentricity of the eccentric 17.

If, on the other hand, it is desired to use the previously determined maximum value for the liquid pressure ar

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to change the pressure ropes, it is only necessary adjust the adjusting screw 36. The adjustment of the adjusting screw causes the effective force of the Spring 26 is changed, via which in turn the value of the pressure that is necessary can be changed. so that the Piston 23 moves the eccentric into its concentric hand position can move.

1 sheet of drawings

Claims (4)

Patent claims: 1. Device for adjusting the delivery rate of a radial piston pump that can be driven via a drive shaft with an annular, rotating eccentric which actuates the pump piston and which is in Depending on the piston which is radially displaceable with respect to its direction of rotation rotating servomotor acting pump delivery pressure in a concentric and dependent manner a spring force acting on the cylinder can be adjusted into an eccentric end position, characterized in that the drive shaft (9) is provided with a shaft connector (12) which is eccentrically disordered with respect to its central axis and which the annular eccentric (17) eccentrically to its longitudinal center axis rotatably receives, wherein the The eccentric is provided with a centrally arranged pin (19) on which the piston (23) of the servomotor (14,15) attacks. 2. Apparatus according to claim 1, characterized in that the shaft connector (12) in an im Servomotor (14, 15) provided bore (13) engages. 3. Apparatus according to claim 1, characterized in that for connecting the piston (23) with the pin (19) provided centrally on the eccentric (17) has a rod connected to the piston (24) is provided with an opening (32) which is inclined with respect to the servomotor axis of rotation and a correspondingly designed, manually reciprocating sleeve (33) receives, which in turn slidably receives the pin. 4. Apparatus according to claim 3, characterized in that the piston (23) on its the rod (24) remote side with the delivery pressure of the pump and on its side close to the rod can be acted upon by the spring force, the sleeve (33) via one against one of its radial sides abutting and in the axis of rotation of the servomotor (14, 15) arranged adjusting screw (36) against the Effect of a spring (41) is axially adjustable.