Type curve more action within the hydraulic motor, discuss the use and maintenance of low speed high torque hydraulic motor has some attention problems.
1 the introduction
In engineering machinery, mining machinery, construction machinery, etc., often using low speed high torque hydraulic motor to drive the walking or promotion agencies. Low speed high torque hydraulic motor is a few axial plunger, majority is radial plunger, radial piston hydraulic motor as part or all of the role of the balance to the rotor under high and low pressure chamber of hydraulic forces, and this kind of motor size and quality, so it is the characteristics of the torque is big, can be operated under high power output at low speed. So, often do not need or use simple reduction gear can be connected to the work mechanism, so as to simplify the machine.
At present, the industrial and mining enterprises using the radial plunger type low speed high torque hydraulic motor many varieties and types, according to its working principle and structure form can be divided into the crankshaft connecting rod type, static balance type and inner curve of acting several more.
Curve within the role type hydraulic motor with big transmission torque, torque ripple is small, quality is small, compact structure, start the advantages of higher efficiency. Therefore, it is the most widely used low speed high torque hydraulic motor. Curve within this article, therefore, more acting hydraulic motor as the key point, to discuss the use and maintenance of the low speed high torque hydraulic motor.
2 hydraulic motor used in some attention
Low speed high torque hydraulic motor in normal use, should first ensure that there is enough oil return back pressure. Back pressure should be to guarantee the stability of hydraulic motor when no-load operation, the minimum output pressure. Usually should be with the increase of rotational speed, the corresponding increase oil return back pressure value of the motor.
Secondly, hydraulic motor due to the bad wear or seal the ageing seal leakage increase, or mechanical friction resistance is too large, hydraulic motor flow instability, torque ripple, causing the appearance of the crawling phenomenon. Don't long time under the lowest stable speed in running. Because, when entering the motor at low speed flow less, leakage for a larger proportion, causes the volumetric efficiency is reduced, leading to crawl. General type hydraulic motor curve more action within the lowest stable speed can reach 0.1 r/min - lr/min.
Again, for the continuous operation of the hydraulic motor, in order to avoid the motor shell in continuous operation in the high temperature caused by friction pair wear gap is too big, cause of large discharge, casing pressure, leakage to the outside of the shell, thus cause the reduce of volumetric efficiency, must be cooled flushing, flushing oil can take away the motor internal impurities, and the radial sealing ring has a cooling effect. Flush loop should be independent of the system (figure 1).
3 what time requirements of hydraulic motor maintenance
3.1 oil return back pressure
To motor work stability, requires a certain amount of oil return back pressure, even so is the inner curve of motor or will cause the wheel from the stator guide rail surface and impact, vibration and noise generation, serious when cause damage. Back pressure value, also cannot too big, according to the inlet and outlet of the hydraulic motor torque and the pressure difference is proportional to the relationship, when the inlet pressure for certain, when the back pressure increases will inevitably make import and export pressure of hydraulic motor is reduced, so cause hydraulic motor rotation. Normally the oil return back pressure should be 0.3 MPa to 1.0 MPa.
3.2 drain pipe line
Drainage pipe line is generally not to the system back to oil, for a motor with a flushing system, drainage pipe line can serve as flush the return pipe. When the motor shaft in the horizontal direction installation, should connect drainage tubing road to shell the drain at the top of the mouth (figure 2). If the motor shaft installed in the vertical direction, the drain pipe should be connected to the motor end cover of the optional oil drain port (figure 2), in the way of drainage pipeline when necessary to increase the appropriate back pressure, back pressure value is too big, otherwise will result in axial sealing ring damage caused by the leakage, the back pressure value should be controlled below 0.5 MPa, the work should be less than 0.8 MPa by measuring the instantaneous peak pressure motor shell), so that the motor internal always full of oil. And can reduce the running noise of the motor.
3.3 add grease on a regular basis
Because the curve more type hydraulic motor speed is low, the load is big, the internal of the rolling bearing is difficult to form oil film, so should be lubricated regularly to fatliquoring, cycles are usually for 2000 h and 3000 h.
3.4 motor installation and replacement
Replacing the motor as possible makes the motor output shaft less or not by the radial force, to ensure that the motor internal support bearing is not affected by extra force, otherwise, the long time use oil distribution institution causes deflection, affect the service life. Therefore, the motor drive shaft and other mechanical connection during installation to ensure the concentric, or adopt flexible connection. For the motor with a torque arm, when installation should connect the motor and the torque arm first, and then fixed torque arm, in case of damage to housing or valve shaft.
3.5 pay attention to capture the abnormal signal
Good at capturing the fault signal, and take timely measures. Noise, vibration and temperature small changes will mean that the motor has a problem. Motors have been used, there is internal leakage, and leakage will increase along with the rise of temperature. Due to internal leakage can make gasket and lining deformation so also external leakage may occur. For motor inside leaking judgment, the author's maintenance experience is: first the motor of the return pipe cut-off, stop system flushing and disconnect the motor and flushing pipeline connection, then the system pressure to a minimum, start the oil pump, pressure will gradually transferred to the normal range, the drainage and pressure measuring point of the motors mouth can be observed shell pressure change and leakage, may, when necessary, the direction of the positive and negative two experiment was carried out.
3.6 keep the oil clean
As far as possible to keep the hydraulic oil clean. Most hydraulic motor fault are hidden behind the drop in the quality of the hydraulic oil. Fault are mostly solid particles (particles), pollutants and overheating of jelly. Experience is summarized, with the hydraulic system of the hydraulic motor oil cleanliness, at least within NAS9 grade shall be maintained. Or hydraulic oil contains impurities, will cause friction within the motor parts surface wear and friction wear into a groove, leakage caused by increased.