EP0712997B1 - Suction regulated internal gear pump - Google Patents

Description

The invention relates to an internal gear pump according to the Preamble of claim 1.

As the development in automotive engineering progresses, the requirements increase of engine power all the time. The engines are said to have a wide speed range can be optimally controlled. To meet this requirement in both the bottom and Valve controls are in the upper speed range of the engine have been developed with which the overlap times of intake and exhaust valves can be changed depending on the speed. For controls to adjust the Valve overlap times, known as so-called VTC (valve timing control) controls become the camshafts for the intake valves and the exhaust valves, respectively adjusted against each other, so that the cams of the two camshafts one Experience phase shift.

In addition to this camshaft adjustment by turning the The cam strokes can also be changed. Doing so will be great Valve strokes with correspondingly longer overlap times in the upper speed range and shorter valve lifts with short or no overlap times in the lower engine speed range. Furthermore, an adjustment of the Valve strokes and / or the overlap times from warm-up to normal operation desirable.

A multi-phase valve timing mechanism is from the "Motortechnische Zeitschrift" 55 (1994) 6, page 342. The cam set used for a six-cylinder engine has two rocker arms. T-waves control depending on the speed simultaneously the two intake and exhaust valves per cylinder. At high speed hydraulic pistons connect the corresponding rocker arms to the T-shafts. At The T-shafts with the levers for low speed become low speed connected. In addition, with this mechanism there is a cylinder deactivation possible. To do this, the T-shafts of the rocker arms for the high speeds disengaged so that only three of the six cylinders are still working.

Ordinary pumps for pumping motor oil, for example vane pumps or conventional gear pumps, convey their working medium with one with the Pump speed constantly increasing delivery pressure or delivery volume flow. The Pumps are usually mechanically driven directly from the motor via a corresponding one Toothed belt drive or another suitable gear driven, so that delivery pressure or volume flow increase with the engine speed. To the required valve control operations even at low engine speeds To be able to perform, the usable pumps must be in the lower speed range of the motor have a steep increase in their volume flow. The known pumps are therefore large with a correspondingly high power consumption executed. As the engine speed increases, they therefore pump more engine oil than is required by the actuating means of the valve control, so that the excess must be returned directly from the pump outlet to a sump.

A pump designed as an internal gear pump is e.g. from DE 39 33 978 known. The drive is usually carried out by the shaft carrying the pinion. The Delivery of such pumps, e.g. the lubrication pump of a motor vehicle engine is only in the lower part of the operating range proportional to the speed. At the top The lubricant or working fluid requirement increases much lower in the speed range than the speed of the engine. This is a suction control of the pump necessary.

The cavitation that occurs is disadvantageous in such a suction control. The through the increase in speed expected linear pressure increase can be in the pressure range such pumps are not held, rather the pressure rises from one certain speed not linear with a lower slope. When falling short the full geometric delivery rate in the work area above the proportionality area cavitation occurs which leads to implosions of the gaseous components of the cell contents leads, so that unwanted noise and damage to the Cell walls are the result. Furthermore, such pumps have higher Speed ranges relatively low efficiencies.

From US-A-2,509,321 an internal gear pump with the features is the generic term of claim 1 known. The feed regulation for the Working fluid is carried out manually via a handle, as well as via a socket and bars.

The invention has set itself the task an internal gear pump with minimal cavitation and high efficiency To make available, in particular for valve control can be used.

This object is solved by the subject matter of claim 1.

Preferred embodiments are described by the subclaims.

The decisive advantage of the new internal gear pump according to the invention lies in that by the controlled supply of working fluid from the outlet mouth into an inlet mouth and the simultaneous interruption of the supply a working cell from working fluid from the inlet channel into this inlet mouth, in which pressure drop and thus cavitation occur with increasing speed would be brought to the higher outlet pressure. This will Cavitation in this delivery cell avoided. Another big advantage is that that because no cavity, i.e. there is no negative pressure in this feed cell, but this is pressurized, this pressure has a positive torque generated on the pinion. This feed cell, which is under higher pressure, is working thus like a hydraulic motor, whereby a very high efficiency can be achieved can.

The pump according to the invention connects by means of a device with increasing pressure in the pressure range sequentially the upstream at these adjacent inlet ports with the pressure area. As a result, as the speed increases, it is ensured that that delivery cell, in which pressure drop and thus cavitation could occur in time with Pressure is applied so that noise and damage are avoided can be.

The above-mentioned device advantageously has one with the outlet mouth connected transfer channel, which via a valve device in at least one feed channel opens, which in turn has an inlet opening communicates. The valve device can thus the regulated supply of Working fluid from the outlet mouth, i.e. the pressure area, into the Control inlet mouth and at the same time the supply of working fluid from the First throttle the inlet channel into this inlet mouth and interrupt it later. For this purpose, such a valve device preferably has a valve piston which by means of a spring supported in the housing against the pressure of the working fluid stored in the transfer channel and access by means of a heel locks or releases the working fluid into the supply channels. The spring offers, at different choice of their stiffness, a way to control the Operating behavior of the valve device, while the head of the valve piston can be designed so that the pressurized working fluid counter the spring force presses against one of its surfaces while it is with its Side surfaces of the feed channels for the working fluid depending on the position of the Valve piston locks or releases.

The valve piston can be in the depressurized state of the transfer channel or up to one predetermined pressure in this against the force of the spring by a stop on Housing in a position where no working fluid from the Transfer channel flows into a feed channel. This state corresponds to the starting position the valve device at low speed or when the Pump. The opposite stop point of the valve piston can thereby be determined that the valve piston in the position where working fluid from flows into all feed channels in its movement against the Direction of the spring force is stopped because the spring is locked.

The inlet mouth for those not to be connected to the transition duct The size of the conveyor cells is preferably limited to the area in which these funding cells extend. This ensures that those Conveying cells with increasing speed with pressure from the high pressure chamber should be applied, can be completely cut off from the suction chamber. In contrast, the outlet mouth can be approximately over the entire area of Extend conveyor cells, which in the conveying direction downstream of the conveyor cells lie, which can be connected to the transition channel. This Formation of the outlet mouth is suitable because of the connection with it standing conveyor cells under high pressure practically during the entire operation stand.

In a preferred embodiment, the end facing away from the head heel forms of the valve piston together with the housing a spring chamber, which for Damping the piston movement is filled with working fluid and over a The bore is in fluid communication with the working fluid in the inlet duct.

The valve device advantageously acts simultaneously as a safety valve in Form of a bypass valve. If the head is at maximum pressure in the pressure range has exceeded the last supply channel to such an extent that decompression occurs a short circuit flow of the working fluid from the pressure area in the Intake channel occurs, the spring therefore only goes to block when an sufficient discharge cross-section is created.

In a further advantageous embodiment of the present invention the pinion of the internal gear pump has two teeth less than the toothed ring, and in the place of disengagement of the teeth is a crescent moon Filler piece fixed to the housing. Here the teeth of the toothed ring be made sufficiently pointed so that the feed cells in the suction area over the Tooth mesh are sealed against each other.

Furthermore, the internal gear pump according to the invention can be characterized in that that the head of the valve piston from a heel base and a lengthways to this subsequent paragraph flag with the same outer diameter, the Guide and the sealing function of the valve piston in the housing bore on the Heels on the exterior of the heel base and heel tab occur.

An internal gear pump according to the invention can advantageously be a suction-controlled one Pump used for valve control according to this invention become.

Figur 1

eine Querschnittsansicht einer erfindungsgemäßen Innenzahnradpumpe, bei der die Stellung der Ventileinrichtung im Anlaufzustand der Pumpe wiedergegeben ist;

Figur 2

eine Querschnittsansicht der erfindungsgemäßen Innenzahnradpumpe in einem Zustand mit gegenüber der Figur 9 erhöhter Drehzahl;

Figur. 3

eine Querschnittsansicht der erfindungsgemäßen Innenzahnradpumpe, wobei die Drehzahl soweit angestiegen ist, daß die Ventileinrichtung bereits eine von der Zufuhr durch ihre Einlaßmündung abgetrennte Förderzelle zur Druckbeaufschlagung vom Druckbereich her freigibt;

Figur 4

eine Querschnittsansicht der erfindungsgemäßen Innenzahnradpumpe, bei der die Ventilvorrichtung eine Stellung eingenommen hat, in welcher alle Einlaßmündungen und Zufuhrkanäle die mit ihnen verbundenen Förderzellen mit unter Hochdruck stehender Arbeitsflüssigkeit versorgen; und

Figur 5

eine weitere Ausführungsform der erfindungsgemäßen Innenzahnradpumpe, wobei das Ritzel zwei Zähne weniger aufweist als der Zahnring und an der Stelle des Außereingriffkommens der Zähne ein mondsichelförmiges, gehäusefestes Füllstück vorgesehen ist.

The invention is explained in more detail below on the basis of exemplary embodiments illustrated in the figures. Show it:

Figure 1

a cross-sectional view of an internal gear pump according to the invention, in which the position of the valve device is shown in the starting state of the pump;

Figure 2

a cross-sectional view of the internal gear pump according to the invention in a state with increased speed compared to Figure 9;

Figure. 3rd

a cross-sectional view of the internal gear pump according to the invention, wherein the speed has risen so much that the valve device already releases a feed cell, separated from the supply through its inlet mouth, for pressurizing from the pressure area;

Figure 4

a cross-sectional view of the internal gear pump according to the invention, in which the valve device has assumed a position in which all inlet openings and supply channels supply the feed cells connected to them with working fluid under high pressure; and

Figure 5

a further embodiment of the internal gear pump according to the invention, wherein the pinion has two teeth less than the toothed ring and a crescent-shaped, housing-fixed filler is provided at the point of disengagement of the teeth.

In Figure 1 is a cross-sectional view of an embodiment of an inventive Internal gear pump shown. The pump has a housing 201 which encloses a gear chamber 206 with a gear ring 202. With the gear ring 202 meshes a pinion 203, which has one tooth less than the toothed ring 202. The pinion 203 forms with the toothed ring 202 successive against each other through the meshing sealing conveyor cells 210, 211, 212, 213, 214, 215 and 216. An inlet channel 204 opens into an inlet opening designed as an inlet kidney 207, which is shown in dashed lines. Furthermore, the inlet duct 204 is in the position shown in Figure 9 via a housing bore 217 with housing shoulders 217a, 217b, 217c and 217d with the feed channels 222a, 222b and 222c connected, which leak into the inlet ports 208a, 208b and 208c.

On the outlet side, the housing has an outlet channel 205 which is in line with that in the gear chamber 206 arranged outlet kidney 209, which is also dashed is shown, is connected. Next is the outlet kidney 209 on their the Outlet opening 205 facing away from the side is connected to a transfer duct 220, which on the side of the housing bore opposite the inlet channel 204 217 opens into the housing shoulder 217a. At the bottom of the case 201 a valve device is provided. A valve piston 221 is located in this position of the valve device in the housing bore 217, a Head shoulder 224 of this valve piston 221 with its front end in the transfer channel 220 strikes against the housing and with its side surfaces the Housing bore 217 on the housing shoulder 217a against the liquid in the transfer channel 220 seals. The valve piston 221 is at its rear end his rear paragraph 229 in a spring chamber 225, in which in a Spring 223 in the direction of the attachment point on the housing (in the left direction in Figure 9) against the pressure in the transfer duct 220 or against the stop of the head heel 224 on the housing 201. The spring chamber 225 is on the right Tightly closed with an unspecified screw plug. A Bore 226 in the valve piston 221 connects its surroundings with that Working fluid filled spring chamber 225, creating a damping effect entry.

Starting from this figure 1, which designates all the components, the Operation of the internal gear pump according to the invention with the help of the others Figures described. The same components are in all figures with corresponding Provide reference numerals. In Figures 2 to 5, however, the better For the sake of clarity, not all, but only the relevant components designated.

In the state shown in Figure 1, the pinion 203 is rotated in the direction indicated by the arrow n. Liquid is sucked in via the inlet channel 204 and, on the one hand, fed to the delivery cells 210 and 211 via the inlet kidney 207. On the other hand, working fluid is also supplied via the housing bore 217 in the space between the valve piston 221 and this housing bore to the feed channels 222a, 222b and 222c and via these to the inlet ports 208a, 208b and 208c, which supply the feed cells 212 and 213 with working fluid. In the state shown in FIG. 1, the pump delivers in the proportional range, ie the delivery volume increases linearly with an increase in the speed n. Since the head shoulder 224 seals the housing bore 217 on the housing shoulder 217a against the liquid in the transfer channel 220, only the delivery cells 214, 215 and 216 are under pressure. The spring force F0 exerts a greater or equal pressure on the valve piston 221 as the pressure P ₀ against the surface of the head heel 224 labeled AK.

In the following functional description it is assumed that a consumer is connected to the outlet channel 205, the hydraulic resistance of which R = ΔP ΔQ is about constant.

The regulation begins when the force exerted by the working fluid in the transfer channel 220 on the head heel 224 becomes greater than the spring force. In Figure 2, the pinion 203 rotates at the speed n1, which is already higher than the limit speed in the proportionality range of the pump. The pressure of the working fluid in the pressure range would increase linearly to a pressure P _{1 '} , so that the valve piston 221 is moved to the right. As a result, the suction angle α _s is reduced from α _{s max} (see FIG. 1) to α _s1 (see FIG. 2). However, the pressure P _{1 '} that could be achieved linearly cannot hold, but drops to P ₁ . This means that the flow rate also drops linearly. At the increased speed n _1, a new delivery rate and a new pressure P _{1 occur} , which is lower than P _{1 '} , but higher than P ₀ . The setting of a pressure P ₁ , which is higher than the pressure P ₀ , is also structurally dependent on the design of the valve device and the pump. If this pressure were not higher than P ₀ , the valve piston 221 would be pushed back into the original position (FIG. 1) by the spring 223, and the process would start again because the speed is increased compared to the initial position. If the pressure P _{1 had} remained at the value P ₁ 'in the pressure range, the throttling effect of the piston 221 moving to the right would have been ineffective on the filling of the feed cell 212 through the head shoulder 224 penetrating the feed channel 222a. Thus, the pressure P ₁ must be between P ₀ and P ₁ '.

A summary of FIGS. 2 and 3 shows what happens when the speed is increased further, here to the speed n ₂ in FIG. 3. The process described above for increasing the speed continues, so that the valve piston 221 is pushed further and further to the right by the pressure increase until, for example, as shown in FIG. 3, a state is reached where the valve piston 221 with its head shoulder 224 reaches Seals the housing bore 217 on the housing shoulder 217c, so that the feed cell designated here 212 is not supplied with suctioned working fluid via the inlet channel 204, but rather via the transition channel 220 and the channels 222a and 208a with working fluid under pressure. The working fluid in the delivery cell 212 is at an increased pressure P ₂ with the downstream delivery cells, so that no cavity is created in it and no negative pressure can develop even in spite of the increase in space. On the contrary, this pressure cell 212 generates a positive torque on the pinion 203 by the application of pressure P ₂ , because its space expands under high pressure and works like a hydraulic motor. This internal differential control thus works with high efficiency. The working fluid under pressure P ₂ is not decompressed to atmospheric pressure, but instead returns its potential energy as mechanical power to the pump drive shaft with a certain loss of flow through the channels. The suction angle in this position is designated α _s2 .

In the state shown in FIG. 4, the speed n ₃ is now increased to such an extent that the valve piston 221 has moved so far to the right that it seals the entire housing bore 217 with its head shoulder 224 against the working fluid in the inlet channel 204 on the housing shoulder 217d. The delivery chamber designated 212 and all of the downstream delivery chambers from it are now supplied with pressurized working fluid either via the outlet kidney 209 or via the transfer channel 220 and the supply and inlet channels 222a, 222b, 208a and 208b crossing them. The spring 223 is pressed onto the block. Half of the feed cells used in the initial stage for suction are separated from the inlet channel 204 and at the same time connected to the high pressure P ₃ , so that they act as a hydraulic motor, as described above. Above all, the pump works practically without cavitation in the entire regulated area, so that no noise is generated. In the speed range from n ₀ to n ₃ , no orifice or other throttle is necessary in the inlet channel 204 because of the internal control just described.

If, as in FIG. 4, the valve piston 221 is pressed to the right up to the spring block, no further internal regulation can take place. With further speed increases the flow rate with reduced slope increases proportionally to the speed rise until in the remaining remaining suction tooth chambers in the area of the short suction kidney 207 cavitation occurs.

The pump described above is mainly suitable for the supply of automatic transmissions with a pressure level up to 25 bar or higher. The The stiffness of the spring 223 determines the steepness of the conveyor line in the regulated one Range and must be adapted to the hydraulic resistance of the consumer become.

FIG. 5 shows a further embodiment of the invention Internal gear pump in two further aspects of the present invention emerge. A first aspect relates to the design of the pump with a Pinion 203, which has two teeth less than the toothed ring 202.

At the point where the teeth of the pinion 203 with the ring gear 202 except Intervention, here is a crescent-shaped, housing-fixed filler 227 intended. The teeth 228 of the toothed ring 202 are designed to be sufficiently pointed, to ensure that the feed cells are sufficiently counter to each other in the suction area for meshing to seal.

The operation of the internal gear pump shown in Figure 5 and the function of the Valve device correspond to that shown in FIGS. 1 to 4.

Another aspect of the invention, which is clear from FIG. 5, relates to the safety valve effect of the valve device. This works as a bypass valve, if at maximum pressure in the pressure area the head attachment 224 the last feed channel 222c has exceeded so far that, under decompression, short circuit from the pressure area enters the inlet channel 204. The spring 223 may only block go if there is a sufficient discharge cross-section at this point is reached. For the function of the valve piston 221 as a safety valve, the Head attachment 224 may be longer than the width of the cutout 230. In FIG Head attachment 224 designed accordingly. If the head base is too short, it loses Pistons his lead.

As further shown in FIG. 5, there is the head shoulder 224 of the valve piston 221 here from a sales base 224a and a sales flag adjoining it longitudinally 224b with the same outside diameter. The leadership and sealing function of the Find valve piston 221 in the housing bore 217 on the housing shoulders the outer surfaces of the heel base 224a and the heel tab 224b. Although the Heel base 224a itself is made narrow, in particular narrower than the width of the feed channels 222 can be a good one through the milled out shoulder 224b Guidance and sealing are guaranteed.

Claims (12)

1. An internal gear pump comprising

   a) a housing (201) with a gear chamber (206),

   b) an annular gear (202) in the housing (201),

   c) a pinion (203) arranged in the annular gear (202) and meshing therewith, which pinion (203) comprises at least one less tooth than the annular gear (202) and forms, together with the latter, successive delivering cells (210, 211, 212, 213, 214, 215, 216), sealed relative to one another by tooth engagement, for the working fluid, and

   d) at least one inlet duct (204) and at least one outlet duct (205) for the working fluid in the housing (201),

   e) the working fluid being fed from the inlet duct via at least one inlet orifice (207, 208a, 208b, 208c) into the intake area of the gear chamber (206) and removed from the pressure area of the gear chamber (206) via at least one outlet orifice (209) into the outlet duct (205), together with

   f) a means (220, 221, 222), which feeds a controlled amount of working fluid from the outlet orifice (209) into at least one inlet orifice (208a, 208b, 208c), while it simultaneously interrupts the feed of working fluid from the inlet duct (204) into this inlet orifice (208a, 208b, 208c),

   characterised in that, as the pressure increases in the pressure area, the means (220, 221, 222) connects the inlet orifices (208a, 208b, 208c) successively adjoining said pressure area in the upstream direction with said pressure area.
2. An internal gear pump according to claim 1, characterised in that the means (220, 221, 222) comprises an overflow duct (220) connected with the outlet orifice (209), which overflow duct (220) discharges via a valve device (221, 222, 223) into at least one feed duct (222a, 222b, 222c), which is in turn connected with an inlet orifice (208a, 208b, 208c).
3. An internal gear pump according to claim 2, characterised in that the valve device (221, 223, 224) comprises a valve piston (221), which is mounted in such a manner as to be adjusted by means of a spring (223) supported in the housing (201) against the pressure of the working fluid in the overflow duct (220) and blocks or releases access of the working fluid to the feed ducts (222a, 222b, 222c) by means of a stepped head portion (224).
4. An internal gear pump according to claim 3, characterised in that, when the overflow duct (220) is in the depressurised state or until a predetermined pressure is reached therein, the valve piston (221) is held in a position against the force of the spring (223) by a limit stop on the housing (201), in which no working fluid flows from the overflow duct (220) into a feed duct (222).
5. An internal gear pump according to either one of claims 3 or 4, characterised in that the valve piston (221), when in the position in which working fluid flows out of the overflow duct (220) into all feed ducts (222), is arrested in its movement counter to the direction of the spring force in that the spring (223) is blocked.
6. An internal gear pump according to any one of claims 1 to 5, characterised in that the inlet orifice (207) for the delivering cells (210, 211) not to be connected with the overflow duct (220) is restricted in size to approximately the area over which these delivering cells extend.
7. An internal gear pump according to any one of claims 1 to 6, characterised in that the outlet orifice (209) extends approximately over the entire area of the delivering cells (214, 215, 216) which lie downstream in the delivering direction of the delivering cells (212, 213) which may be connected with the overflow duct (220).
8. An internal gear pump according to any one of claims 1 to 7, characterised in that the end of the valve piston (221) remote from the stepped head portion (224) forms, together with the housing (201), a spring chamber (225) which is filled with working fluid to damp the piston movement and is in fluid connection with the working fluid in the inlet duct (204) via a bore (226).
9. An internal gear pump according to any one of claims 1 to 8, characterised in that the valve device (221, 223, 224) simultaneously acts as a safety valve in the form of a bypass valve if, when the highest pressure prevails in the pressure area, the stepped head portion (224) has moved so far beyond the last feed duct (222c) that, under decompression, a short-circuit stream of working fluid is formed from the pressure area into the inlet duct (204).
10. An internal gear pump according to any one of claims 1 to 9, characterised in that the pinion (203) comprises two less teeth than the annular gear (202) and a crescent-shaped filler member integral with the housing is provided at the disengagement point of the teeth.
11. An internal gear pump according to clam 10, characterised in that the teeth on the annular gear are sufficiently sharp for the delivering cells (210, 211, 212) to be sealed relative to one another by tooth engagement in the suction area.
12. An internal gear pump according to any one of claims 3 to 11, characterised in that the stepped head portion (224) of the valve piston (221) consists of a step base (224a) and an adjacent step lug (224b) along said base (224a) with the same external diameter, wherein guidance and the sealing function of the valve piston (221) in the housing bore (217) at the stepped housing portions (217a, 217b, 217c, 217d) take place at the outer surfaces of the step base (224a) and the step lug (224b).

Images