EP1544474B1 - Radial pump - Google Patents

Abstract

The radial pump, especially a cooling medium pump for an internal combustion engine has at least one first group (5) of impeller blades (6) pivotable around axes (9) parallel to the impeller axis. The group of pivotable impeller blades is located in the region of the flow outlet (22). The group of pivotable impeller blades are automatically pivotable in dependence upon the rotational speed. The pivotable blades are pivot-mounted in the region of the flow outlet side ends of fixed impeller blades (4).

Description

The invention relates to a radial pump, in particular coolant pump for an internal combustion engine, with at least a first group of rotating about axes parallel to the impeller rotor blades, wherein the group of pivotable blades in the region of the flow outlet of the impeller is arranged, wherein the group of pivotable blades a group the impeller rigidly connected rigid blades is preceded, wherein the group of pivotable blades are automatically pivotable in response to the speed.

When cooling internal combustion engines mainly engine speed-dependent radial pumps are used. With coolant pumps larger vehicle internal combustion engines, there is often the requirement to deliver a significant flow rate even at low speeds. But this is associated with a very large flow rate at maximum speed, which in turn leads to unacceptably high pressures in the coolant circuit. Short circuits to reduce the quantities flowing through the engine circuit must be made with large cross-sections and are always associated with power dissipation. When designed for maximum speed, however, there is a risk that the pressure increase in idle not sufficient to maintain sufficient cooling.

From EP 1 310 678 A1 a radial pump with impeller blades elastically deformable by Coriolis forces of the coolant flow is known, wherein the exit angle defined between blades and an impeller tangential plane decreases with increasing rotational speed. Depending on Coriolis forces, the entire rotor blades are elastically deformed or deflected. A small deformation or deflection already has a relatively large impact on the flow rate and efficiency. Therefore, this construction is very sensitive to tolerances, which requires high production requirements. The blades are either made of an elastically yielding material or are each hinged about an axis per blade and articulated against the force of return springs, with simultaneous adjustment of the blades is ensured by a synchronizer ring. However, moving blades made of elastic material have the disadvantage that vibrations can lead to material fatigue and premature failures.

US 2,946,288 A describes a centrifugal pump with a constant speed rotating impeller with sliding blades, all Blades are synchronized and experienced not only a rotational, but also a translatory movement. The adjustment is made by a pressure-controlled, separate mechanism from the outside. The blades are connected by bolts to a control disc, which can be adjusted via a twisting mechanism relative to the pump rotation. By adjusting the blades, the characteristic of the radial pump can be moved depending on the adjustment of the adjustment to set a desired operating point can. The disadvantage is that a considerable effort is required for the external control.

GB 1 159 371 A discloses a centrifugal pump impeller with rotatably mounted blades, which adjust themselves according to the flow conditions, whereby shock losses at the blade tips are to be avoided. Furthermore, radial pumps with pivoting blades are known from the publications US Pat. No. 3,033,015 A, US Pat. No. 3,510,229 A and EP 0 166 104 A1, wherein the rotor blades collapse when the direction of rotation is changed. DE 1 119 671 B shows a wastewater centrifugal pump with flexible channel hinged tape, which releases a larger channel when coarser body passes and then moves back to the starting position. A synchronizer for simultaneous movement of all blades is not provided.

Radial pumps with pivotable blades, which are connected to the impeller rigidly connected rigid blades, and which are automatically or positively controlled movable, are known from the publications US 3,090,543, DE 14 03 504 A and DE 296 06 296 U1. Uncoordinated oscillating movements of the pivotable blades can not be ruled out, which adversely affects the efficiency.

The object of the invention is to increase the efficiency of a radial pump in the simplest possible way.

According to the invention this is achieved in that the pivotable Laufschaufein are simultaneously adjustable by a synchronizing ring. By synchronizing a simultaneous blade adjustment is achieved.

The blade adjustment is not done externally depending on certain variables, but automatically depending on the pump speed, and it is particularly advantageous if the blades are loaded by at least one spring element in the direction of a maximum exit angle defining basic position. At low speeds, there is thus no or only a slight adjustment, whereas the adjustment increases more and more up to the maximum speed. The reset mechanism reduces the adjustment again automatically, if the forces are reduced again by reducing the speed.

The blades are thus not adjustable in their entirety, but only the rotatably mounted ends of the blades. These have the greatest influence on the characteristic curve position in the map, specifically on the pressure reduction in the upper rpm range. An adjustment of the inlet areas of the blades is not required and not desired, the rigid blades can thus be designed for optimal conditions.

Flow separation and turbulence are avoided when the pivotable blades are articulated in the exit area of the rigid blades.

The adjustment of the wings leads to a shift in the efficiency and performance characteristics over the entire speed range. The power loss generated with rigid design of the wings in the upper speed range is significantly reduced by means of the combination of rigid and pivotable blades.

The blades may be at least partially made of sheet steel or plastic.

Fig. 1

ein Laufrad einer erfindungsgemäßen Radialpumpe;

Fig. 2

die Vorderseite des Grundkörper des Laufrades mit den starren Laufschaufeln;

Fig. 3

die Rückseite des Grundkörpers des Laufrades;

Fig. 4

einen Synchronring des Laufrades;

Fig. 5

eine schwenkbare Laufschaufel in einer Schrägansicht; und

Fig. 6

ein Pumpenkennfeld.

The invention will be explained in more detail below with reference to FIGS. Show it

Fig. 1

an impeller of a radial pump according to the invention;

Fig. 2

the front of the main body of the impeller with the rigid blades;

Fig. 3

the back of the main body of the impeller;

Fig. 4

a synchronizer ring of the impeller;

Fig. 5

a pivotable blade in an oblique view; and

Fig. 6

a pump map.

The impeller 1 consists of a base body 2 with a group 3 of fixed blades 4 and a group 5 of pivoting blades 6. The pivoting blades 6 are in the region of the flow outlet 22 of the impeller 1, in the region of the flow outlet side ends 8 of the rigid blades 4 via bearing pins 10, 11 in holes 12 of the base body 2 and a dashed line in Fig. 1 indicated cover 7 rotatably mounted about axes 9 parallel to impeller axis 1a, wherein the pivotable blades 6 are arranged between the base body 3 and the cover 7.

For synchronization of all pivotable blades 6, each pivotable blade 6 on an attack pin 13 for a synchronizing ring 14, wherein the synchronizing ring 14 is guided over sliding surfaces 17 on running surfaces 15 of the cover plate 7. With reference numeral 16 recesses in the base body 2 for receiving return springs 18 are referred to, which engage projections 19 of the synchronizing ring 14. The engagement pins 13 are guided in slots 20, 21 of the base body 2 and the synchronizing ring 14.

At low speeds, the pressures on the pivotable blades 6 are small, the flow rate Q and the pressure difference Δ _p are unchanged compared with a designed in one piece impeller with rigid blades. As is apparent from Fig. 1, take the pivoting blades 6 their maximum circulation diameter, wherein the exit angle α ₁ sets, which is measured between the pivotable blades 6 and a tangent plane ε. At high speeds, the Coriolis forces cause the coolant flow to deflect the pivotable blades 6 counter to the return springs 18 arranged in the recess 16 between the base body 2 and the synchronizer ring 14 in the direction of smaller exit angles α ₂ . This causes a lowering of the pressure difference Δ _p . Although the centrifugal forces counteract the reduction of the exit angles α ₁ , α ₂ , with a suitable design of the return springs 18, the desired effect arises. The fact that no throttling is required at higher speeds, eliminating the throttle losses.

Fig. 6 shows a pump characteristic diagram for the radial pump, is in each case the pressure difference Δ _p with the flow rate Q applied. I and II are the engine throttle curves of a conventional radial pump with rigid impeller blades. In contrast, the dashed line III shows a motor displacement curve of the radial pump described with a group 3 of rigid blades 4 and a Group 5 6 out of turnable impeller vanes can clearly be seen that for the curve III at low speeds, a sufficiently high pressure difference Δ _p for maintaining the cooling capacity is guaranteed and that on the other hand Inadmissible high pressures in the coolant circuit can be avoided at high engine speeds.

Claims (5)

1. A radial-flow pump, particularly a coolant pump for an internal combustion engine, with at least one first group (5) of impeller vanes (6) turnable about axles (9) parallel to the impeller axle (1a), said group (5) of turnable impeller vanes (6) being positioned in the outlet area (22) of the impeller (1), and with a group (3) of rigid impeller vanes (4) fixedly attached to the impeller (1) being placed before the group (5) of turnable impeller vanes (6), the turnable impeller vanes (6) of group (5) moving automatically depending on the rotary speed of the impeller (1), characterised in that the turnable impeller vanes (6) can be simultaneously adjusted by a synchronizing ring (14).
2. A radial-flow pump according to claim 1, characterised in that the turnable impeller vanes (6) are pivotably mounted in the area of the ends (8) of the rigid impeller vanes (4) on the outlet side.
3. A radial-flow pump according to claim 1 or 2, characterised in that the turnable impeller vanes (6) can be elastically adjusted by Coriolis forces of the coolant flow, with the exiting angles (α₁, α₂) defined between the turnable impeller vanes (6) and the tangential planes (ε) of the impeller (1) preferably decreasing as the impeller speed increases.
4. A radial-flow pump according to claim 3, characterised in that the turnable impeller vanes (6) are loaded by at least one spring element (18) in the direction of an initial position defining a maximum exit angle (α₁).
5. A radial-flow pump according to any of claims 1 to 4, characterised in that the impeller vanes (4, 6) are made at least partly of sheet steel or some plastic material.

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