Directional valves

فهرست عناوین اصلی در این پاورپوینت

فهرست عناوین اصلی در این پاورپوینت

● Directional valves
● Electrically governed continuously adjustable valves
● Servo valves
● Continuously adjustable valves
● Accessories
● System concepts
● Constant pressure sources
● Big pictures
● Directional valves
● Servo valves
● Proportional valves
● Accessories
● System concepts
● Velocity drives
● Force drives

نوع زبان: انگلیسی حجم: 6.65 مگا بایت
نوع فایل: اسلاید پاورپوینت تعداد اسلایدها: 78 صفحه
سطح مطلب: نامشخص پسوند فایل: ppt
گروه موضوعی: زمان استخراج مطلب: 2019/05/16 03:25:45

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اسلایدهای پاورپوینت مرتبط در پایین صفحه

عبارات مهم استفاده شده در این مطلب

عبارات مهم استفاده شده در این مطلب

., valve, pressure, position, flow, control, directional, source, rate, constant, adjustable, large,

توجه: این مطلب در تاریخ 2019/05/16 03:25:45 به صورت خودکار از فضای وب آشکار توسط موتور جستجوی پاورپوینت جمع آوری شده است و در صورت اعلام عدم رضایت تهیه کننده ی آن، طبق قوانین سایت از روی وب گاه حذف خواهد شد. این مطلب از وب سایت زیر استخراج شده است و مسئولیت انتشار آن با منبع اصلی است.

http://www.hds.bme.hu/letoltesek/targyak/BMEGEVGAG11_ENG/hps_vi.ppt

در صورتی که محتوای فایل ارائه شده با عنوان مطلب سازگار نبود یا مطلب مذکور خلاف قوانین کشور بود لطفا در بخش دیدگاه (در پایین صفحه) به ما اطلاع دهید تا بعد از بررسی در کوتاه ترین زمان نسبت به حدف با اصلاح آن اقدام نماییم. جهت جستجوی پاورپوینت های بیشتر بر روی اینجا کلیک کنید.

عبارات پرتکرار و مهم در این اسلاید عبارتند از: ., valve, pressure, position, flow, control, directional, source, rate, constant, adjustable, large,

مشاهده محتوای متنیِ این اسلاید ppt

مشاهده محتوای متنیِ این اسلاید ppt

directional valves classification schemes spool valves or poppet valves switching or continuously adjustable valves number of ports and positions the kind of governing and positioning unit directional valves ۱. spool valves or poppet valves have always leakages can be totally sealed need relatively large displacements because a positive overlap is needed for sealing need smaller displacements to let fluid through preferred in all other cases because of their flexibility and lower price preferred for large flow rates need radial and axial pressure relief spool valves poppet valves directional valves ۲. switching or continuously adjustable valves directional valves work either in certain switching positions or they are continuously adjustable. latter by electrohydraulic or electric governing units. directional valves ۳. number of ports and positions two positions three positions basic symbols ۴ ۳ valve with ports operation positions and governing elements directional valves ۴. kind of governing and positioning unit by hand electrically or electrohydraulically cross section symbol electrically governed continuously adjustable valves servo valves servo valves proportional valves they are able to govern a very large output power with a very small input power. large masses have to be moved in a short time against varying forces to precise positions. these valves are very expensive because they have to be manufactured with very high accuracy. because of this their operation is also expensive because the fluid has to be very well filtered. they have usually two for very large flow rates three amplifying stages. servo valves double nozzle – impinging plate bridge circuit servo valves operation if there is no current there is no displacement the valve body is kept in the middle. if there is current the iron core is displaced and the impinging plate that is rigidly coupled with it is also displaced and a pressure drop is created. note that there is a small negative overlap the manufacturing must be very good. there must always be a flow. disadvantage it is difficult to hold the zero position because of dry friction or contamination. solution there are also three stage servo valves. they are used for very large powers. continuously adjustable valves proportional valves continuously adjustable proportional magnets are able to adjust continuously and precisely the position of a directional valve. the magnetic force is proportional to the current and nearly independent of the position. the core reaches out far from the coil. they might be connected with a position control where hysteresis effects are smaller. they are often used for flow rate control but all pressure valves can work with a proportional magnet instead of a spring. they are more precise. accessories liquid reservoir tasks storing of necessary liquid volume conducting heat away from the system de airing of the liquid large surface long stay of the liquid separation of condensed water carrying element of other system components pumps valves pipes etc. pipes steel of flexible hoses. key point sealing accessories filter surface filter volume filter – an order of magnitude better but not cleanable it can be before the pump after the pump before every sensitive elements or in the back flow line. system concepts delivering of liquid by flow sources pressure sources in case of flow sources normally for each actuator a separate source. one pressure source can deliver several actuators parallel. pressure source should not be controlled by restriction valves because the losses will be then too high. better is to control by adjusting the displacement volume of the actuator. it can happen with a hydromotor easily but for a hydraulic cylinder one needs a hydraulic transformer. this is called secondary control. → exp. on next slide system concepts cont. basically there are two main subgroups ۱. the pressure is always constant in this case the main task is to find a control system to change the flow rate for the oscillating flow rate needs of the actuators. various control mechanisms can be used here ۲. the pressure is not constant secondary control see previous page load sensing control much more complicated system concepts constant pressure sources pump with pressure relief valve not very effective – lot of lost energy. the displacement volume or the rotational speed of a pump can be controlled by measuring the pressure. in fact flow rate control but indirectly pressure control. the constant valve is for safety it limits the maximum possible flow rate through the system and prevents a breakdown of the pressure. these valves are all between the actuator and the reservoir. this has the advantage that the actuator is between two liquid columns that are both under pressure. vdr restriction valve vw direction valve all three versions have a ۴ ۳ valve all three versions have two restriction valves one constant and one adjustable position drives system concepts drives constant pressure sources position drives with the adjustable resistance the velocity can be controlled is a simple circuit. problem is drifting in the holding position since the spool valve has a leakage. solves this problem by putting a ۲ ۲ directional valve before the ۴ ۳ valve. this seals perfectly. in addition a double check valve prevents the cylinder from moving. is even better. it allows a very accurate positioning. the directional valve ۱ has the job to switch between a creeping mode and a normal speed mode. from the creeping mode it is easy to stop accurately. hold ۱ normal speed ۲ creeping speed constant pressure sources velocity drives vw directional valve ev fast forward er fast backward av working forward ar working backward vsz flow control valve vdr restriction valve simpler circuits can be derived. if for example no working backward mode is needed then vw۴ and vsz۱ can be omitted. if the working velocity is so small that the flow rate is around the leakage flow rate large errors occur. in this case spool valves may not be applied instead pilot operated check valves. directional valve positions constant pressure sources force drives holding of work pieces lifting of weights forming of materials simple circuit without adjustment of force. why is it a constant force drive because the pressure …

کلمات کلیدی پرکاربرد در این اسلاید پاورپوینت: ., valve, pressure, position, flow, control, directional, source, rate, constant, adjustable, large,

این فایل پاورپوینت شامل 78 اسلاید و به زبان انگلیسی و حجم آن 6.65 مگا بایت است. نوع قالب فایل ppt بوده که با این لینک قابل دانلود است. این مطلب برگرفته از سایت زیر است و مسئولیت انتشار آن با منبع اصلی می باشد که در تاریخ 2019/05/16 03:25:45 استخراج شده است.

http://www.hds.bme.hu/letoltesek/targyak/BMEGEVGAG11_ENG/hps_vi.ppt

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