EP0681656B1 - Process for regulating the capacity of lubricant pumps and lubricant pump therefor - Google Patents

Abstract

A process is disclosed for regulating the capacity of lubricant pumps. The capacity of the pump is regulated by the pressure at the pump outlet or at a consumer site, so that when the pressure increases the pump capacity is effectively reduced. A regulatable lubricant pump, in particular a vane cell pump (1), has a pressure-controlled regulating arrangement (2). In order to obtain a process for controlling lubricant pumps and a corresponding lubricant pump which as a whole consume less energy, the feeding capacity of the pump is additionally limited in an independent manner by detecting the temperature and/or speed of rotation. As for the lubricant pump itself, it is provided with a regulating arrangement (3) having a sensor (4) for the speed of rotation and/or temperature, as well as a regulating member (5), which regulate the effective pump capacity depending on the speed of rotation or temperature, besides the pressure regulating arrangement.

Description

The present invention relates to a method for regulating the Pump performance of lubricant pumps, in which the pump performance over the prevailing at the pump outlet or at a consumption point Pressure is controlled so that the pressure increases Pump power is effectively reduced. In addition, the present concerns Invention a controllable lubricant pump with a Control device through which to limit the flow rate Pump power is effectively reduced. A corresponding procedure and a corresponding device are from DE 33 33 647 A1 known.

In the known device is a controllable lubricant pump (Vane pump) with automatic pressure control with an in described a housing on one side pivoted cam ring, whose eccentricity from the pumped medium Pressure medium area by means of a spring biased counter bracket control device is adjustable, as well as with suction and pressure openings in the housing, whereby to the radial Support the wing of said vane pump against the Hubring at least two guide rings in chambers on the two End faces of the rotor body are arranged radially movable and a channel connects the pressure side with the chambers. For customization the amount of lubricant and the pressure to the requirements and the respective state of the internal combustion engine is provided that the counter bracket biased by a compression spring a stop has and the control device on the to tap the Hubringes opposite side is a control piston, the Inside via a control line directly with the pressure side of the pump connected is.

However, the application of the present invention is not limited to vane pumps. In particular, the invention can also be applied to all controllable pumps, in particular also to those that only have a so-called loss control, i.e. which, when a predeterminable pressure is exceeded, excess lubricant over a Bypass bypass at points of consumption, only the pumped through the system Lubricant quantity (effective delivery quantity) is reduced, but not that by the pump self-funded amount. Of course, compared to such a system are adjustable Pumps preferred, in which the delivery capacity of the pumps or their Delivery volume and not only the effective delivery volume can be influenced.

The term "effective delivery volume" is the volume of the lubricant understood which per unit of time through the consumption points, the corresponding feed and Discharges and any upstream units, such as Oil filter, under pressure is pumped. Oil which e.g. via bypass lines and to a pump sump is not considered part of the effective funding volume. That too Drainage of oil via bypass lines limits the pressure at the pump outlet and in entire system, whereby however no energy saving can be achieved. A noteworthy Energy reduction is only achieved if the pump-driven pump is used from the outset Volume is adapted to the requirements as with variable vane pumps or with multi-stage Constant pumps with register control.

Lubricant pumps of this type are primarily used for supplying lubrication points on internal combustion engines, in particular for motor vehicles.

The lubricant requirement or minimum requirement of an internal combustion engine is, however, of a number different factors. The operating temperature is a key factor here the engine and / or the relevant lubrication points as well as the lubricant.

When cold, the oil generally used as a lubricant has a high viscosity and is difficult to push through narrow gaps in the lubrication points. At the same time, however, the lubricant requirement is also in the cold state of the internal combustion engine not excessively high, since the parts that move against each other in the cold state in general also have a smaller game against each other and the viscosity of the oil is large and therefore less oil can be passed through.

With this starting position, the effective delivery capacity of the Lubricant pump set so that a predetermined maximum pressure at the pump outlet was not exceeded. It is understood that in the cold state of an engine, because of the in this temperature range of highly viscous oil when starting the engine and thus directly coupled lubricant pump, the pressure at the outlet of the lubricant pump is initially relative increases steeply since the flow resistance of the oil through the lubricant points is relatively large. Here there is a risk that individual components in the lubricant system, e.g. an oil filter, are damaged or destroyed by the application of excessive pressure. Out for this reason a pressure limitation is usually provided, which is either too much derives pumped lubricant via a bypass or the pump delivery rate immediately limited, so that the delivered lubricant at the predetermined limit pressure can be conveyed through the lubricant system. With increasing temperature however, the flow resistance in the lubricant system decreases, so that the delivery rate gradually can be increased, which happens, among other things, that the pressure is slightly below of the limit pressure drops, as a result of which the effective delivery rate or the pump output is increased accordingly. The control characteristic of the known controllable pumps is included generally set so that the outlet pressure remains approximately constant and only the delivery rate varies depending on the flow resistance in the lubricant system.

In the past, it was believed that such a regulation meant that different lubricant requirements of an internal combustion engine in the cold and in the warm Condition is sufficiently taken into account. For cost reasons, lubricating oil pumps are for Internal combustion engines are generally designed to operate at the maximum operating temperature and an oil of the lowest permissible viscosity (= most critical lubrication state) with a certain Reserve still reliably cover the engine's oil requirement, at any speed. Of the The design point for the pump capacity is the oil requirement of the engine at idling speed when hot and with a correspondingly low-viscosity oil. Even in this condition Provide the pump with a certain minimum flow rate and thus a certain minimum oil pressure, the pump shaft generally being directly coupled to the motor, as previously mentioned.

Another critical condition is high engine speeds when the engine is hot. Here one becomes significant higher oil pressure is required than at low engine speeds. The known pressure control is therefore set to this operating state with an appropriate safety reserve.

Because in the state of the art the pressure is kept constant at this high level, the only exceptionally at low temperatures and at the same time at low speeds becomes clear, it is clear that an essential over a wide range of normal operating conditions Pumped higher amount of oil through the system and maintained a much higher oil pressure is considered to correspond to the actual demand (minimum oil requirement or minimum oil pressure). You stop the pressure constant, the so-called result for different temperatures Swallowing curves of internal combustion engines as a function of the speed, as shown in FIG. 1 are shown schematically.

As a rule, the volumetric efficiency of the oil pumps decreases with decreasing temperature due to lower leakage losses. At the same time, the oil consumption of the Motors with falling temperature. As a result, at temperatures lower than that maximum operating temperature of the oil pumps in every operating state, i.e. at any Engine speed, more oil is pumped than the engine needs. The engine throughputs of the Figure 1 does not reflect the amount of oil the engine actually has at the specified Speed and temperature as a minimum amount of lubricant, but only what he needs at constant pressure and the specified temperatures and speeds of lubricant records. The conveyance of lubricant that is not actually required in this quantity under pressure naturally costs energy.

In contrast, it is an object of the present invention to provide a method for controlling To create lubricant pumps and a corresponding lubricant pump which overall have a lower energy requirement.

With regard to the above-mentioned method, this object is achieved in that a temperature and / or a speed detection an additional one from any pressure-dependent regulation independent regulation or limitation of the effective delivery volume takes place.

In the method according to the invention it is further provided that the temperature control permitted flow rate increases with temperature.

With regard to the above-mentioned, preferably controllable, lubricant pump, the The object underlying the invention is achieved in that a control device is provided, which has a temperature sensor and / or a speed sensor and an actuator which regardless of any pressure control, the effective delivery rate depending on the Temperature and / or speed reduced.

The statement: "independent of any pressure control" means in the sense of the present Invention does not necessarily mean that the temperature or speed control without any influence to the pressure control or from any pressure control in any operating condition remains unaffected, but only that temperature and / or speed as an additional, independent parameters for the setting of an oil flow and the resulting Oil pressure can be used.

This means that the delivery rate is not only set so that at the points of consumption or any upstream or downstream aggregates, a specifiable maximum pressure is not exceeded, Instead, depending on the temperature and / or the speed, an additional further limitation of the flow rate can be adjusted so that the pressure at the outlet of the Pump or at the pressure measuring points provided for pump control still clearly remains below the predefinable maximum pressure, namely when the system z. B. at the suitable points measured temperature or in the low speed range has correspondingly lower lubricant requirements, so that the lubricant is not below the in particularly critical operating conditions require higher pressure or in a corresponding smaller amount must be provided (see Figure 2).

In a preferred embodiment of the invention, the lubricant pump according to the invention is an adjustable vane pump. Adjustable vane pumps have the advantage that the mechanical adjustment of their cam ring in a relatively simple way Delivery volume can be adjusted. This has the advantage that the pump shaft directly with the Motor can be coupled and still a regulation of the delivery volume independent of the motor is possible. Of course, other control devices are also conceivable, with which For example, the speed at which a lubricant pump is driven via pressure and / or temperature-related actuators is regulated. However, this requires one independent drive for the pump.

In a preferred embodiment of the invention, a wedge with a Thermostats, such as a bimetallic strip, are provided, the one of which has a wedge flank the cam ring engages so that the cam ring is adjusted when the wedge is displaced.

A bimetal strip, for example, can be part of the actuator or as an actuator itself are provided, such a bimetallic strip also being designed and can be arranged that, if desired, it engages directly with the cam ring and this is adjusted depending on the temperature of the bimetal strip.

Other measuring sensors and control methods are also familiar to the person skilled in the art. Measurement and control can also take place, for example, via electrical elements, such as temperature-dependent electrical components, especially resistors, in an electrical Control loop are measured and emit an electrical signal as an output variable, the one adjustment of an actuator corresponding to the electrical signal.

A special case of such a system is e.g. a stepped piston, one part of the surface for Pressure control from the outlet pressure of the pump or the pressure at a point of consumption is applied. Another surface of the stepped piston can optionally be pressurized depending on the speed or temperature via a temperature or speed-controlled valve. At low temperature or speed, for example Valve must be open so that pressure is also applied to the second partial surface of the stepped piston is, which leads to a stronger adjustment of the stepped piston, so that the cam ring is set that there is a smaller delivery volume and thus a relatively small operating pressure sets. At a higher temperature or speed, the valve is switched over the temperature or Speed control closed, so that only a smaller area of the piston of Pressure is applied so that the pump to a higher outlet pressure and a higher Delivery rate is set.

The corresponding control and activation elements should be as simple as possible, so that the pump as a whole does not become much more complicated. This is especially true for the Use of the pump in standard situations, e.g. in internal combustion engines. In case of Motors or generally systems with a need for lubricants that change very strongly Operating conditions are exposed, but can also be a more complex temperature control the amount of lubricant appropriate and reasonable, provided that this additional effort correspondingly large energy savings due to the possible reduction in the amount of lubricant delivered.

Figur 1

die Motordurchsatzmengen eines Motors in Abhängigkeit von der Drehzahl eines Motors bei verschiedenen Temperaturen,

Figur 2

den erforderlichen Mindestöldruck eines Motors in Abhängigkeit von der Drehzahl,

Figur 3

die Motordurchsatzmengen in Verbindung mit der Mindestdruckkurve gemäß Fig. 2,

Figur 4

das Prinzip einer Temperaturansteuerung des Hubringes einer Flügelzellenpumpe mittels eines Keils,

Figur 5

die Temperaturansteuerung des Hubringes über ein Bimetallelement,

Figur 6

die Temperaturansteuerung der Hubringverstellung über ein elektrisch gesteuertes Element und

Figur 7

eine Flügelzellenpumpe mit einem Stufenkolben als gleichzeitig druck- und temperaturabhängiges Regelelement.

Further advantages, features and possible uses of the present invention result from the following description of preferred embodiments with reference to the associated figures. Show it:

Figure 1

the engine throughput quantities of an engine as a function of the speed of an engine at different temperatures,

Figure 2

the required minimum oil pressure of an engine depending on the speed,

Figure 3

the engine throughput quantities in connection with the minimum pressure curve according to FIG. 2,

Figure 4

the principle of a temperature control of the lifting ring of a vane pump by means of a wedge,

Figure 5

the temperature control of the cam ring via a bimetal element,

Figure 6

the temperature control of the cam ring adjustment via an electrically controlled element and

Figure 7

a vane pump with a stepped piston as a pressure and temperature-dependent control element.

A total of four so-called engine throughput quantities of an engine can be seen in FIG Temperatures T1 = 25 ° C, T2 = 50 ° C, T3 = 90 ° C and T4 = 130 ° C. It is applied Oil flow rate or the amount absorbed by the engine in liters per minute compared to Engine speed. The course of the individual curves shows that the pressure is constant The amount of lubricant passed increases with increasing speed, although this Increase is not proportional to the speed.

At the same time, however, one can recognize the different curve shape for different ones Temperatures that at a given speed the engine at low temperature significantly uses less oil than at high temperature.

In the engine throughput quantities shown in FIG. 1, the pressure in the feed lines to the engine has always the same value (e.g. 5 bar).

This pressure is designed so that in the most critical state, i.e. with the greatest oil demand, So at the highest temperature and the highest speed, with an oil of the lowest permissible viscosity the oil requirement of the engine is still covered.

From Figure 2 it can be seen that the minimum oil pressure typically with the speed up to a value of about 5 bar in the lubricant system increases. Of course they hang exact values and the curve shape very much on the type and size of the engine and the concrete design of the lubricant system, so that the numbers given only as Example values are to be understood and are not intended to restrict the subject matter of the invention. The Prior art pumps have therefore generally been designed to regardless of the temperature and essentially also independent of the speed Always keep the pressure at the value for the lubricant system in question as the minimum oil pressure was intended under critical operating conditions (e.g. the 5 bar mentioned). The Vane pumps that are typically used also easily reach much higher ones Outlet pressures. In practice, pressure limits have so far only been used provided that the pressure was kept constant, only a limit pressure was selected, the with a certain safety reserve above the highest minimum oil pressure in critical Operating conditions was and which is already achieved at relatively low speeds ..

In particular at low temperatures, the one provided by the pressure limitation Maximum pressure is reached very quickly and an uncontrolled pump delivers especially in low speed range much more oil than it meets the needs of the engine.

Conventional, regulated pumps only ever pump as much oil as the one set Corresponds to the maximum pressure, but this pressure is only required at high speeds Minimum oil pressure. In all other operating states, pressure and flow rate can be changed without further be less. This results primarily for low speeds and at low speeds Operating temperatures a considerable saving potential, for example by using a Speed and temperature dependent control of the engine oil pressure well below the limit value conventional systems is reduced, on which the control system otherwise to Protection of pressure-sensitive components is set. This results in delivery quantities or Engine throughputs for the engine, which are shown in dashed lines in Figure 3, where recognizes that even at high operating temperatures and low engine speeds there is considerable potential for savings. Such operating states occur, for example in city traffic with motor vehicle engines frequently. Due to the reduced amount of oil that the Engine is supplied in this operating state, which, however, completely for the lubrication requirement is sufficient, you reduce the energy consumption of the lubricant pump and thus the Total energy requirement of the engine. This is one of the main goals of the present Invention achieved. The combination of pressure control and temperature control means that in the oil flow only brought in as much energy as to ensure sufficient Oil supply to the engine is necessary. Examples of technical realizations are in the Figures 4 to 7 shown.

A vane pump 1 with an adjustable lifting ring 2 is shown schematically in FIG. A temperature controller for the eccentricity of the cam ring 2 is also shown schematically with respect to the pump shaft 6. The temperature controller 3 consists of a temperature sensor or a thermosensitive element 4, a wedge 5 and a spring 7, which are in a row next to the Cam ring are arranged. The temperature controller 3 is located inside, for example Pump housing and is in direct contact with the oil to be pumped, which by radial Openings penetrate into the cam ring and through axial openings in the pump housing again can leak. So that the thermosensitive element 4 is essentially at the temperature of the lubricant held. In the simplest case, element 4 could be, for example Be an element whose thermal expansion is relative in the temperature range of interest is large (for example, element 4 could contain a gas volume). When the temperature rises would then expand the element 4 and thereby the wedge 5 against the effect move the spring 7 to the right so that the cam ring 2 around the axis 8 upwards could swing. For this purpose, a compression spring 9 is provided, for example, which on a Actuating pin 10 of the cam ring 2 acts and this up against a flank of the wedge presses. In order to obtain the desired setting characteristic of the pump, i.e. an increase in Flow rate with increasing temperature, the cam ring 2 is relative to the pump shaft 6 so arranged that the cam ring eccentricity with respect to the shaft 6 by pivoting the Hubringes 2 upward about the axis 8, so when the wedge 5 moves to the right. Conversely, when the temperature decreases, the cam ring 2 is flanked by one edge of the wedge 5 pressed down against the action of the spring 9 when the temperature of the lubricant system decreases or is lower, the wedge 5 shifting from right to left. By Suitable guides can ensure that the wedge 5 is not in the transverse direction to his can shift the intended travel range.

In Figure 5, the vane pump can be essentially identical to the vane pump 4, only the control direction 3 is by a leaf spring or a bimetallic strip 4 ' replaced, which simultaneously the function of a temperature sensor and an actuator takes over. As the temperature increases, the two are firmly connected Metal strips of the bimetallic strip 4 'differ, so that depending on the relative arrangement of these two metal elements, the curvature of the leaf spring 4 'increases or decreases and the Eccentricity of the cam ring 2 with respect to the pump shaft is reduced accordingly or is enlarged.

In Figure 6, an electrically controllable temperature controller is shown as an actuator 5, the measured by a temperature sensor and measured in a corresponding Control signal is implemented, which adjusts the cam ring in the desired direction, i.e. so, that its eccentricity increases with the temperature of the lubricant. The remaining Details of the preload of the cam ring 2 by a spring 9 and the relative arrangement of lifting ring 2, bearing axis 8 and pump shaft 6 can with the embodiment of Figure 4 in be essentially identical.

FIG. 7 shows a further variant of the adjustment of the lifting ring of a vane pump shown. Here are the pressure-dependent control, the temperature-dependent control and possibly also a speed-dependent control on one and the same actuator 5 realized, which is a step piston in this case. For example, a first partial area 11 of the step piston 5 constantly acted upon by the outlet pressure P2 of the pump, so that this provides a maximum pressure limitation. In addition, a second stage of the Piston 5 on a surface 12 to which a pressure P1 can be applied, which is the simplest Case is identical to pressure P2 and comes from the same source. In a supply line to the Pressure space from which surface 12 can be pressurized is a controllable valve 13 is provided, which switches depending on the temperature and / or speed. At Low speeds and / or low temperatures, for example, the valve 13 can be opened be so that both surfaces 11 and 12 are pressurized and thereby a larger Total force against the spring 9 acts as if only the surface 11 were pressurized. The cam ring and shaft of the vane pump are arranged so that the eccentricity of the Lift ring by moving the actuator or step piston 5 down in Figure 7 is reduced. With increasing temperature and / or speed, the valve 13 is closed, see above that only the surface 11 is pressurized and the cam ring under the effect of Spring 9 again in the direction of greater eccentricity and thus a higher delivery rate Vane pump is adjusted. As already mentioned, the valve can not only be temperature-dependent, but can also be switched depending on the speed. You have in addition to the pure Maximum pressure limitation and delivery volume control an additional limitation of the Delivery volume depending on the temperature and / or the speed of the motor.

The structure of the pump is somewhat reduced by the additional control elements provided more complicated, but the energy savings that can be achieved with the pump outweigh these small ones Disadvantage without further ado, especially since the embodiment according to FIG. 5 is a very simple implementation of the additional control according to the invention shows.

Claims (2)

1. A method of controlling the pump output of a lubricant pump, in which the effective pump output is reduced by pressure-dependent control via the pressure prevailing at the pump outlet or at a consumer point, characterised in that the delivery rate is additionally and independently restricted via ascertainment of the temperature and/or rotary speed, the delivery rate allowed by temperature control in comparison with the delivery quantity allowed by the pressure-dependent control being limited with increasing temperature and/or rotary speed.
2. A regulable lubricant pump, particularly a cell pump (1) with a pressure-controlled control means (2), characterised in that a control means (3) is provided, which has a rotary speed sensor and/or a temperature sensor (4) and a positioning member (5), which, alongside the pressure control means, control the effective delivery quantity as a function of the rotary speed and/or temperature, the control element of the lubricant pump being electrically operable while the positioning member (5) is a differential piston, to at least one part of which pressure can be applied via a valve (13) which can be operated as a function of temperature.

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