Patent Application
20120171049
The present invention pertains to a lubricant pump for delivering lubricant to at least one lubricating point, as well as to a lubricating system with such a lubricant pump. The lubricant pump features, e.g., a lubricant container, a pump unit, a drive assigned to the pump unit, at least one lubricant outlet and a control unit assigned to the drive.
Some known lubricant pumps are provided with a functional monitoring system that delivers a corresponding malfunction signal to a monitoring device, e.g., if an impermissibly high pressure at the lubricant outlet indicates that the lines leading to the lubricating points are blocked. It is also known that the drive of the pump unit or the drive of an agitator blade that may be provided in the lubricant container automatically switches off at an excessively high load and, if applicable, also delivers a malfunction signal. When such a malfunction signal is registered in the monitoring device, the pump usually is completely stopped and needs to be reactivated by an operator after the cause of the malfunction is eliminated. This is a time-consuming and labor-intensive procedure.
Such an intervention by the operator in order to activate the pump is also required if no malfunction of the pump has occurred, but the viscosity of the lubricant merely has increased at low temperatures to such a degree that the function of the lubricant pump is impaired. Consequently, it has already been proposed to provide a heater that heats parts of the lubricant pump. Such heaters are usually switched on individually without realizing a demand-actuated operation of the heater.
The present invention, in contrast, is based on the objective of making available a lubricant pump and a lubricating system of the aforementioned type that are particularly suitable for use in extremely cold areas such as, e.g., in arctic environments.
According to the invention, this objective is essentially attained with the characteristics of Claim 1. According to the basic concept of the invention, the lubricant pump additionally features at least one heating element that can be actuated in a demand-based fashion by the control unit assigned to the drive and/or a separate control unit. In other words, the heater according to the present invention can always be purposefully utilized when a malfunction of the lubricant pump can be attributed to increased lubricant viscosities at low temperatures. In such instances, the pump therefore no longer needs to be completely stopped and the cause of the malfunction no longer needs to be eliminated by an operator, but the lubricant pump rather can be automatically restarted by actuating the heating element.
An increased viscosity of the lubricant at low temperatures, as can occur, e.g., in arctic environments or under harsh winter conditions, can cause different malfunctions within a lubricant pump. For example, blocking of the driving motor may occur if the resistance becomes excessively high for movement of the agitator blade in the lubricant container. It would also be possible that the flow resistance in one of the lubricant lines exceeds the permissible system pressure such that a conventionally provided pressure control valve opens. This causes the lubricant to be delivered into the open rather than to the lubricating points. Another malfunction may consist of the pump element being unable to take in lubricant of increased viscosity from the lubricant container. The utilization of a heater in the lubricant pump only makes it possible to eliminate the malfunctions in the first and the last above-cited instance. However, an excessively high flow resistance in one of the lubricant lines cannot be eliminated by using a heater within the lubricant pump. According to the invention, it is therefore proposed that the control unit activates the heating element individually and in dependence on the respective malfunction.
Independently of the above-described characteristics, the control device of a lubricant pump of the initially cited type is, according to a basic principle of the present invention, realized and designed in such a way that the above-described malfunctions caused by an increased viscosity of the lubricant at excessively low temperatures are detected by the control device and corresponding countermeasures are initiated.
According to an additional development of this inventive principle, it is proposed that the lubricant pump additionally features at least one temperature sensor that is connected to the control unit and/or another control unit in order to actuate the at least one heating element in dependence on the temperature determined by the temperature sensor. Due to this temperature sensor, the control unit is able to detect whether a malfunction can be attributed to an increased viscosity of the lubricant due to an excessively low temperature and to then individually eliminate this malfunction by switching on the heating element.
According to another embodiment of the invention, at least one pressure sensor is provided in the lubricant pump and preferably assigned to the lubricant outlet. The pressure sensor is preferably connected to the control unit or another control unit in order to actuate the at least one heating element in dependence on the lubricant pressure determined by the pressure sensor. If the flow resistance in one of the lubricant lines exceeds the permissible system pressure due to excessively low temperatures, however, the use of a heating element in the lubricant pump does not eliminate the cause of the malfunction. In this respect, an unnecessary operation of the heating element can be prevented in dependence on the lubricant pressure determined by the pressure sensor.
An agitating device such as, e.g., an agitator blade may be provided in the lubricant container. This agitating device can be actuated by the drive of the pump unit and/or by another drive. A measuring device is preferably assigned to the drive of the agitating device in order to determine the current consumption thereof and connected to the control unit and/or another control unit in order to actuate the at least one heating element in dependence on the current consumption. Consequently, the measuring device enables the control unit to determine whether the driving motor is blocked due to an excessively high resistance of the agitator blade in the lubricant container that is caused by an increased viscosity of the lubricant at low temperatures. Instead of measuring the current consumption of the drive, the measuring device may also measure another variable that is suitable for determining the state of the lubricant in the lubricant container and then evaluated by the control unit. Such a variable may consist, e.g., of the torque required for driving the agitator blade and/or the speed of the agitator blade.
It is preferred to design the control unit in such a way that it detects a state in which the drive for the agitating device is blocked due to excessively low temperatures, based on an evaluation of the data of the temperature sensor, the measuring device and/or the pressure sensor. In this respect, it is preferred that the control unit switches on the at least one heating element in this state in order to increase the temperature of the lubricant in the lubricant pump and the lubricant container, respectively. The quantity of heat can be controlled with the heating time, if applicable, in dependence on the ambient temperature. It is preferred that the heating process begins prior to a lubrication cycle, wherein the ambient temperature is initially measured and a quantity of heat that prevents the agitator blade from being blocked is subsequently supplied.
According to another embodiment of the invention, the control unit is designed in such a way that it detects a state in which the pump unit is unable to take in lubricant from the lubricant container due to excessively low temperatures, based on an evaluation of the data of the temperature sensor, the measuring device and/or the pressure sensor. In this state, the control unit preferably also switches on the heating element provided in the lubricant pump in order to supply heat to the pump system. According to another embodiment of the invention, it is proposed to design the control unit such that it detects a state in which an excessively high flow resistance exists in a line connected to the lubricant outlet due to excessively low temperatures, based on an evaluation of the data of the temperature sensor, the measuring device and/or the pressure sensor. It is preferred that the control unit switches off the drive of the pump unit and/or the drive of the agitating unit in this state because an actuation of the lubricant pump would cause the lubricant to be delivered into the open via the pressure control valve rather than to the lubricating point. This malfunction cannot be eliminated by heating the pump system because the viscosity of the lubricant increases in the lubricant lines outside the pump. Consequently, it is also unnecessary to output a malfunction signal, but rather preferred to wait until the ambient temperature increases and the resistances in the lines drop.
A particularly compact and protected construction of the inventive lubricant pump can be achieved in that the control unit, the temperature sensor, the measuring device, the pressure sensor, the at least one drive and the pump unit are accommodated in a common housing and/or arranged on a common carrier. The housing may also fulfill a certain insulating function in order to retain the heat generated by the heating element within the region of the pump through which the lubricant flows.
The invention also pertains to a lubricating system with a lubricant pump of the above-described type and a line that is connected to the lubricant outlet of the lubricant pump and to a distributor. In this case, the distributor preferably features a functional sensor that is connected to the control unit of the lubricant pump and/or another control unit in order to actuate the at least one heating element of the lubricant pump in dependence on the operability of the distributor. In other words, it is possible to refrain from the energy-intensive utilization of the heater if a malfunction of the distributor occurs, namely even if the viscosity of the lubricant increases within the lubricant pump due to excessively low temperatures.
In addition, at least one other heating element that can be actuated by the control unit and/or another control unit may also be assigned to the distributor and/or the line. This actuation preferably takes place in dependence on the data of the functional sensor, the temperature sensor, the measuring device and/or the pressure sensor. In this way, not only can temperature-related malfunctions within the lubricant pump be eliminated, but also malfunctions that are caused by the viscosity of the lubricant increasing within the distributor or in a line leading to or away from the distributor at low temperatures.
An embodiment example of the invention is described in greater detail below with reference to the figures. In this respect, all described and/or graphically illustrated characteristics form the object of the invention individually regardless of the composition thereof in the claims or the references thereof to other claims. The only FIGURE schematically shows a perspective representation of an inventive lubricant pump. In order to provide a better overview, certain components of the lubricant pump, such as the cover of the housing, are not illustrated such that the individual components are visible in the figure.
The inventive lubricant pump 1 features a lubricant container 2, in which a supply of lubricant is stored. An agitator blade or similar agitating device may be provided in the lubricant container 2 in order to thoroughly mix and maintain the free-flowing consistency of the lubricant that may consist, e.g., of lubricating grease. In the figure, a carrier 3 is provided on the lower side of the lubricant container 2, wherein the carrier can be closed with a housing cover and the components of the lubricant pump 1 are arranged on this carrier.
In order to deliver lubricant from the lubricant container 1 to a lubricant outlet, the lubricant pump features a pump unit that can be actuated by a driving motor 4. The driving motor 4 may also drive the agitating device in the lubricant container 2.
In addition, a control 5 that can individually actuate the driving motor 4 and the pump unit and/or the agitating unit is also provided on the carrier 3. In the embodiment shown, a cartridge heater 6 is also arranged on the underside of the lubricant container 2 on the carrier 3 and can be actuated by the control 5. In this case, the cartridge heater 6 is arranged in the vicinity of the pump unit such that the cartridge heater can heat the lubricant situated in the lubricant container 2, as well as the pump unit.
The inventive lubricant pump 1 is furthermore equipped with a pressure sensor 7 and a temperature sensor 8 that are also arranged on the carrier 3. The pressure sensor 7 and the temperature sensor 8 are connected to the control 5 that evaluates the data acquired by the pressure sensor 7 and the temperature sensor 8 and activates the driving motor 4 and/or the cartridge heater 6 in dependence on the data of the sensors. The temperature sensor 8 measures the ambient temperature. The pressure sensor 7 measures the lubricant pressure at the lubricant outlet or in the line connected thereto. In addition, the control 5 may also determine, e.g., the current consumption of the driving motor 4 or the torque required for driving the pump unit and/or the agitator blade with the aid of a corresponding measuring device.
In this way, the control 5 is able to detect different malfunctions of the lubricant pump 1 that are caused by an increased viscosity of the lubricant due to excessively low temperatures. An evaluation of the ambient temperature and/or the current consumption of the driving motor 4 makes it possible to determine whether the driving motor is blocked due to an excessively high resistance of the agitator blade in the lubricant container 2. In motors that are protected against blocking, the power supply is usually interrupted. The current consumption can be evaluated on motors that do not feature this protection. An evaluation of the ambient temperature and the data of the pressure sensor 7 makes it possible to determine whether the flow resistance in the lines connected to the lubricant outlet is so high that a pressure control valve is actuated and lubricant is delivered into the open. An evaluation of the ambient temperature, the current consumption of the driving motor 4 and the data of the pressure sensor 7 makes it possible to determine whether the pump unit is able to take in grease from the lubricant container 2. If applicable, the data of a functional sensor of a distributor, not shown, may also be evaluated for this purpose, wherein said distributor forms part of the lubricating system and is connected to the lubricant outlet of the lubricant pump 1.
1 Lubricant pump
2 Lubricant container
3 Carrier
4 Driving motor
5 Control
6 Cartridge heater
7 Pressure sensor
8 Temperature sensor
| Number | Date | Country | Kind |
|---|---|---|---|
| 202010016721.3 | Dec 2010 | DE | national |
