JP4191857B2 - Uniaxial eccentric screw pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single-shaft eccentric screw pump that transfers a transfer object by rotating an externally threaded rotor eccentrically in an internally threaded stator.
[0002]
[Prior art]
As is well known, the single-shaft eccentric screw pump is eccentrically rotated by inserting a male screw rotor connected to the drive shaft of a drive motor provided at one end of the pump casing via a connecting rod so as to be rotatable in the female screw stator. It is comprised so that a transfer thing may be transferred. And since the stator which is a main part is formed with rubber, idle operation is strictly prohibited.
[0003]
For this reason, various methods have been devised in the past for detecting or preventing the idling of the pump. For example, as shown in FIGS. 5 and 6, through-holes 101b and 201b are provided in the thick rubber portions 101a and 201a of the stators 101 and 201, and the temperatures at which the temperatures of the stators 101 and 201 are detected in the through-holes 101b and 201b. A detection sensor 102 is attached, and the temperature detection sensor 102 is connected to the control means 103 as shown in FIG.
[0004]
Then, the control means 103 determines that the engine is idling when the temperature detected by the temperature detection sensor 102 exceeds the set temperature (the temperature at the time of normal operation in which the transferred object is transferred + approximately 5 ° C. as a guide). By outputting an alarm command signal to the alarm means 104, the alarm means 104 is operated to issue an alarm and alert the user to prevent idling. As described above, the method of detecting based on the temperatures of the stators 101 and 201 is the most versatile and can be realized at a relatively low cost, so that it is actually used.
[0005]
In addition, various methods have been proposed to detect idling, such as detection of the liquid level of a liquid transfer material or detection of a decrease in flow rate, but they are reliable and versatile. The range of use is limited.
[0006]
[Problems to be solved by the invention]
By the way, in the method of detecting the idling operation based on the temperature of the stators 101 and 201 described above, the through holes 101b and 201b are provided in the thick portions 101a and 201a of the stators 101 and 201 in order to attach the temperature detection sensor 102. For this reason, it is difficult to be affected by the heat generation inside the stator, but the heat transfer through the through holes 101b and 201b is large, and the temperature rise during idling is slow. For this reason, the set temperature cannot be made higher than the temperature during normal operation, so that it is difficult to cope with changes in the temperature of the transferred material, and when the set temperature is increased, detection when an idle operation occurs is delayed. In particular, the stator varies depending on the size, rubber material, etc., but it is a fairly expensive part.If it is burned in the idling operation, it causes a large loss and must be detected reliably. It is necessary to avoid stopping as much as possible.
[0007]
Further, if the through holes 101b and 201b are provided, they are essentially not suitable for so-called CIP (cleaning in plant) cleaning.
[0008]
Furthermore, it has been confirmed from the test data that the temperature increase of the stator during non-through operation is greater in the non-through hole than in the through hole, and this is considered to be due to the influence of heat generation inside the stator. .
[0009]
Accordingly, an object of the present invention is to provide a single-shaft eccentric screw pump capable of accurately detecting idling operation by using a non-through hole instead of a through hole as a hole for attaching a temperature sensor for detecting the temperature of the stator. And
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, in the uniaxial eccentric screw pump for transferring the object to be transferred, the male screw rotor that is rotationally driven by the driving means is rotatably inserted in the female screw stator and rotated eccentrically. A non-through hole in which the inner peripheral surface side of the stator is closed, a temperature detection sensor that is fitted and inserted into the non-through hole, detects the temperature of the stator, receives a signal from the temperature detection sensor, When the temperature exceeds the set temperature, the first idling operation determining means for judging that the idling operation is performed and a signal from the temperature detection sensor, the gradient of the temperature rise of the stator exceeds the set temperature gradient. Sometimes, a second idling determination unit that determines idling is provided. Here, the gradient of temperature rise means the rate of change in the temperature rise of the stator per unit time.
[0011]
According to the first aspect of the present invention, since the temperature detection sensor is provided in the non-through hole of the stator as described above, in the low rotation / low discharge pressure region, the transferred object is present during normal operation. The temperature of the stator and the temperature of the transferred object do not change much at the same time, while the temperature rise of the stator becomes gradual and large during idle operation where there is no transferred object. The temperature can be set large enough with a sufficient margin of about 15 to 20 ° C. than the temperature during normal operation. Therefore, in the low rotation / low discharge pressure region, the first idling determination means accurately determines that idling is performed when the stator temperature exceeds the set temperature.
[0012]
On the other hand, in the high rotation / high discharge pressure region, the stator temperature exceeds the set temperature because the temperature of the stator becomes considerably higher than the temperature of the transferred object even during normal operation due to the heat generated inside the stator. However, the idling operation cannot be detected, but the idling temperature rises more than the normal operation due to the heat generated inside the stator. Since it can be determined that the engine is idling when the temperature exceeds, the second idling determination means accurately determines that the idling operation is performed when the gradient of the temperature rise of the stator exceeds the set temperature gradient. Thus, it is possible to reliably detect idling regardless of the operation region. When it is determined that the engine is idling as described above, the warning means may be driven to issue an alarm, thereby alerting the operator, or to the driving means that rotationally drives the rotor. The power supply may be cut off and the pump may be stopped immediately.
[0013]
By the way, for reasons such as eliminating erroneous determinations, only one of the first and second idling determination means operates properly in the low rotation / low discharge pressure region and the high rotation / high discharge pressure region. It is also possible to do so, but if they are idling only by using them together, depending on the driving area, any idling determination means will determine idling, so it is necessary to use them separately Absent.
[0014]
According to a second aspect of the present invention, in the uniaxial eccentric screw pump according to the first aspect, the second idling determination unit sequentially calculates a gradient of temperature rise based on the temperature of the stator detected at a constant cycle, and the calculation is performed. When the gradient of the temperature rise exceeds the set temperature gradient, it is determined that the idling operation is performed.
[0015]
According to the invention of claim 2, the temperature of the stator is sequentially detected at a constant period, the gradient of the temperature rise is calculated based on the detected temperature, the gradient of the temperature rise is compared with the set temperature gradient, When the detected gradient of temperature rise exceeds the set temperature gradient, it is determined by the second idling operation determining means that the idling operation is being performed.
[0016]
According to a third aspect of the present invention, in the uniaxial eccentric screw pump according to the first or second aspect, the first and second idle operation determination means include a set value changing unit capable of changing the set temperature and the set temperature gradient, respectively. It is to be prepared.
[0017]
According to the invention of claim 3, the set temperature and the set temperature gradient are changed in the set value changing units of the first and second idling determination means by operating, for example, a setting switch on the operation panel.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
FIG. 1 is a sectional view of a mounting portion of a temperature detection sensor which is a part of a uniaxial eccentric screw pump according to the present invention.
[0020]
The single-shaft eccentric screw pump is configured to transfer an object by rotating a male screw rotor that is rotationally driven by a driving means (for example, a drive motor) into a female screw stator 1 made of rubber so as to rotate eccentrically. As shown in FIG. 1, an attachment hole 2 is formed in the thick part 1 a of the stator 1, and the temperature detection sensor 3 is fitted into the attachment hole 2 and attached. The mounting hole 2 is a non-through hole in which the inner peripheral surface side is closed and the stator outer cylinder 4 side is opened.
[0021]
The temperature detection sensor 3 is attached by a fixture 5 so that a part of the temperature detection sensor 3 protrudes to the outside of the stator outer cylinder 4, and a connector 8A on the cable 7 side for sending a signal to the controller 6 (see FIG. 2). A connection receptacle 8B is provided for detachable connection.
[0022]
The controller 6 receives a signal from the temperature detection sensor 3, and when the temperature of the stator 1 exceeds a set temperature, the controller 6 determines first idle operation determination means 6A and the temperature detection. And a second idling determination unit 6B that determines that idling is performed when the temperature rise gradient exceeds the set temperature gradient upon receiving a signal from the sensor 3; Here, the set temperature and the set temperature gradient are determined by the first idling operation determining means 6A mainly judging idling operation in the low rotation / low discharge pressure region, and the second idling operation judging means 6B mainly judging high rotation / high. It is set so that idling is determined in the discharge pressure region.
[0023]
In the low rotation / low discharge pressure region, when the temperature of the stator 1 exceeds the set temperature, the first idling operation determining unit 6A determines that the idling operation is performed, and the alarm unit 10 is activated. Output a signal. As a result, the warning means 10 issues a warning notifying the worker that the vehicle is idling, and alerts the user.
[0024]
In the high rotation / high discharge pressure region, the second idling determination means 6B determines that idling is in effect when the temperature rise gradient exceeds the set temperature gradient, and the alarm means 10 is activated. Output a signal. As a result, an alarm is issued in the same manner as described above, and the user's attention is drawn. Here, in the high rotation / high discharge pressure region, the gradient of temperature rise is sequentially calculated at a constant cycle, and if the calculated temperature rise gradient exceeds the set temperature gradient even once, it is determined to be idling. However, the second idling determination unit 6B may perform idling when the gradient of the temperature rise sequentially detected at a constant cycle exceeds the preset temperature gradient by the set number of times. Therefore, the determination accuracy of the idling operation is increased, so that erroneous determination does not occur. It is also possible to further improve the determination accuracy by combining other conditions (pump rotation speed, measured temperature, etc.) with the determination, or accumulating the temperature gradient value and detecting the accumulated value.
[0025]
That is, the determination of the idling operation by the second idling determination means 6B is as follows. As shown in FIG. 3, the temperature of the stator is read at a constant cycle, and based on the temperature of the stator 1, the present and past (one The temperature gradient before the cycle) is divided by the time corresponding to the cycle, and the temperature gradient is sequentially calculated, and the calculated temperature gradient is compared with the preset temperature gradient. When it is determined that the gradient of the temperature rise exceeds the set temperature gradient for the set number of times, an operation signal is output to the alarm means 10, and the alarm means 10 generates an alarm such as an alarm buzzer or an alarm lamp. By calling out, it is designed to alert the operator.
[0026]
In addition, when the alarm is not held by a switch (not shown), the alarm is released when the calculated temperature rise gradient is less than the set temperature gradient. On the other hand, when holding of the alarm is selected, the alarm is maintained until the power is turned off.
[0027]
Each of the first and second idling determination means 6A and 6B includes a set value changing unit (not shown) that can change the set temperature and the set temperature gradient, and according to the operating conditions, The preset temperature and preset temperature gradient can be changed.
[0028]
If comprised as mentioned above, since the temperature detection sensor 3 which detects the temperature of the stator 1 is attached by being inserted in the attachment hole 2 which is a non-through hole formed in the thick part 1a of the stator 1, The inside of the stator 1 (portion to which the transferred material is transferred) is not open to the outside, and it is possible to cope with CIP cleaning and the like.
[0029]
In the low rotation / low discharge pressure region, the first idling determination means 6A reaches the set temperature, and in the high rotation / high discharge pressure range, the second idling determination means 6B causes a temperature increase gradient. When the set temperature gradient is exceeded, it is determined that the engine is idling, and the idling of the pump can be accurately detected in any operation region. In other words, in the case of idling, since any idling determination means 6A, 6B is judged to be idling according to the operating region, idling is determined by any idling determination means 6A, 6B. When it is determined that, for example, by issuing an alarm, it is possible to alert the operator and prevent the stator from being burned in the idling operation, and to avoid stopping the operation due to false detection It becomes.
[0030]
In the above embodiment, the idle operation of the pump is detected based only on the stator temperature and the temperature rise gradient, but a separate sensor for detecting the temperature of the transferred material is also provided to detect the temperature of the transferred material. If this is done, especially when the transferred material is 80 ° C or higher, which is considerably higher than the ambient temperature, the temperature inside the pump will not increase if it is idling. It can also be increased.
[0031]
In the above embodiment, the attachment 5 of the temperature detection sensor 3 is positioned outside the stator outer cylinder 4, but the attachment 5 is connected to the stator outer cylinder 4 and the stator as shown in FIG. It is also possible to position it in a recess formed in one thick portion 1a, and the manner of attaching the temperature detection sensor 3 is not limited.
[0032]
【The invention's effect】
The present invention is implemented in the form as described above, and has the following effects.
[0033]
According to the first aspect of the present invention, the temperature of the stator is detected by the temperature detection sensor, and when the temperature of the stator exceeds the set temperature by the first idling operation determination means, the idling operation is determined. When the gradient of the temperature rise of the stator exceeds the set temperature gradient, it is determined that the idle operation is performed. Thus, it is possible to accurately detect the idling operation even in the low rotation / low discharge pressure region or in the high rotation / high discharge pressure region.
[0034]
The invention according to claim 2 sequentially calculates the temperature increase gradient based on the stator temperature detected at a constant period, and determines that the calculated temperature increase gradient exceeds the set temperature gradient is idling. Thus, the determination accuracy of the idling operation by the second idling determination means is increased. Therefore, the determination accuracy in the high rotation / high discharge pressure region in which the idling is mainly determined by the second idling determination means is increased.
[0035]
In the invention of claim 3, since the set temperature and the set temperature gradient can be changed according to the operating conditions in the set value changing units of the first and second idling determination means, it is optimal according to the operating conditions. Can be controlled.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a mounting portion of a temperature detection sensor of a uniaxial eccentric screw pump according to the present invention.
FIG. 2 is a block diagram of a control system of the pump.
FIG. 3 is an explanatory diagram of determination of idling based on a temperature rise gradient of a second idling determination unit of the pump according to the present invention.
FIG. 4 is a view similar to FIG. 1 for another embodiment.
FIG. 5 is a view similar to FIG. 1 showing a conventional example.
6 is a view similar to FIG. 4 showing a conventional example.
FIG. 7 is a view similar to FIG. 2 showing a conventional example.
[Explanation of symbols]
1 Stator 1a Thick part 2 Mounting hole (non-through hole)
3 Temperature detection sensor 4 Stator outer cylinder 6 Controller 6A First idle operation determination means 6B Second idle operation determination means 10 Alarm means

Claims (3)

In a single-shaft eccentric screw pump that transfers a transfer object by inserting a male screw rotor that is rotationally driven by a drive means into a female screw stator so as to be rotatable and eccentrically rotating,
A non-through hole formed in the stator and closed on the inner peripheral surface side of the stator;
A temperature detection sensor that is fitted into the non-through hole and detects the temperature of the stator;
Receiving a signal from the temperature detection sensor, and when the temperature of the stator exceeds a set temperature, a first idling determination unit that determines idling;
And a second idling operation determining unit that receives a signal from the temperature detection sensor and determines idling when the gradient of the temperature rise of the stator exceeds a set temperature gradient. Eccentric screw pump. The second idling determination means sequentially calculates a temperature rise gradient based on the temperature of the stator detected at a constant cycle, and when the calculated temperature rise gradient exceeds the set temperature gradient, the idling operation is performed. The single-shaft eccentric screw pump according to claim 1, wherein the single-shaft eccentric screw pump is determined to be. 3. The single-shaft eccentric screw pump according to claim 1, wherein each of the first and second idling determination means includes a set value changing unit capable of changing the set temperature and the set temperature gradient.

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