[go: up one dir, main page]

CN2044054U - Multi-function solar energy temp. collecting room - Google Patents

Multi-function solar energy temp. collecting room Download PDF

Info

Publication number
CN2044054U
CN2044054U CN88221546U CN88221546U CN2044054U CN 2044054 U CN2044054 U CN 2044054U CN 88221546 U CN88221546 U CN 88221546U CN 88221546 U CN88221546 U CN 88221546U CN 2044054 U CN2044054 U CN 2044054U
Authority
CN
China
Prior art keywords
temperature collecting
heat
incubator
collection
temperature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
CN88221546U
Other languages
Chinese (zh)
Inventor
那玉恒
那继山
那任远
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to CN88221546U priority Critical patent/CN2044054U/en
Publication of CN2044054U publication Critical patent/CN2044054U/en
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/40Solar thermal energy, e.g. solar towers

Landscapes

  • Building Environments (AREA)

Abstract

The utility model discloses a multi-function solar energy temperature collecting room belonging to the construction work making use of solar facilities. The multi-function solar energy temperature collecting room integrally combines a temperature collecting box, a reflection of light heated board and temperature collecting devices which are three solar facilities Transparent covers of insulating wall of heat retaining bottom form the main work of the multi-function solar energy temperature collecting room-the temperature protection room type temperature collecting box. The outside of the southern wall of the temperature collecting box is provided with the temperature collecting devices which are serrate and are connected in parallel. The reflection of light heated board is arranged on the transparent cover. Temperature protection facilities used for heating, cooling and storing heat are arranged in the temperature collecting box. The multi-function solar energy temperature collecting room is widely used by drying rooms with high and low temperature and is used for heating bitumen, obtaining heat, etc. The maximum temperature can reach more than 200 DEG C.

Description

Multi-function solar energy temp. collecting room
Multifuctional solar temperature collecting chamber belongs to the construction work that utilizes solar facilities.
Domestic applied solar energy equipment is existing historical for many years.Reduce three class formations substantially: 1, being used for aspect drying rooms such as timber, Chinese medicine, pottery, vermicelli, is by adorning a large amount of corrugated heat collectors in the front of common nonadiabatic property house outside and the left and right sides.Monolithic becomes the row floor space big, and the big efficient of heat waste is low, and interior temperature is up to 78 ℃ and sees " solar energy " quarterly; 2, pitch heating aspect is as solar facilities with the collection incubator, earlier asphalt temperature is elevated to 70~80 ℃, and then utilize the far infrared reheat to the temperature that construction needs, see " Heilungkiang science and technology newspaper 1985,11,29 " and " Liaoning science and technology newspaper 1986,4,21 "; 3, method of caustic heating asphalt temperature can reach 110 ℃, residual oil temperature raising to 120 ℃, and the invention people rears people for Ezhou, Hubei highway division Shao.Then volume increase is produced in expansion but output is little, and the expensive difficulty of cost is big.
Only utilize a certain solar facilities to reach a kind of function in order to overcome above-mentioned situation, and production efficiency is low, the narrow not enough spy who brings of temperature range has invented multifuctional solar temperature collecting chamber.
Design of the present invention is: will collect incubator, reflective warming plate and three kinds of solar facilities of heat collector from the solar energy theory in conjunction with the experience of construction work and realize multi-functional in conjunction with forming one.Constitute major project by insulation end adiabatic wall, transparent housing--the collection incubator of insulated building formula, in the collection incubator, be provided with and heat cooling, heat-storage heat-preserving facility, four sides wall and ground are adiabatic heat-insulation formula structure, 1 meter on ground is with upper part brushing reflectorised paint or sticking reflecting material around the inwall, form on wall reflector, the collection incubator and push up the plane housing that is provided with the gradient about 15% to the south, housing adopts two-layer light transmittance to be not less than 0.8 transparent heat insulating material manufacturing, directly absorbs solar radiation; Thing both sides and north at housing equal housing area 1-2 doubly by adorning the gross area.The reflective warming plate of adjustable angle, it can be refracted to solar radiation heat on the transparent housing of collection incubator, makes the heat of collection incubator increase the temperature rising, plays insulation effect when close night; The plate combination heat collector in parallel of the adjustable serration type in the elevation angle is installed in wall outside, collection incubator south.Its lower end is provided with collecting incubator and communicates, and the upper end all communicates with collection incubator and atmosphere and has the pipeline of valve, and ground low air is sent in the collection incubator after the heat collector heating again.When if the temperature height does not need to continue to heat up in the collection incubator, the pipeline valve that leads to the collection incubator up and down can be closed, open the valve that the upper end leads to atmosphere; On the wall of collection incubator, establish several ventilation openings (ventilation opening is provided with insulation cover in the wall outer end) as required.In the collection incubator blower fan is arranged, lower the temperature, dehumidify, open ventilation opening when removing vaporize water, start blower fan when needs.If when needing to increase humidity in the collection incubator, can be in the east side of heat collector or the west side by adorning a solar water heater, delivering hot water in the collection incubator, wherein one section hot-water line in the collection incubator is drilled to several water spray apertures, just forms high temperature wet fog shape when hot water sprays; Will be more than 30 ℃ the time when " multifuctional solar temperature collecting chamber " serviceability temperature, then the end at the collection incubator is provided with the control room.With the blower fan start stop switch, the water service pipe valve is located in the control room, grasps temperature, the humidity that collects incubator from control room and the observation window on the wall wall that collects incubator, utilizes the start and stop of blower fan to be controlled; When " multifuctional solar temperature collecting chamber " does storehouse, vegetable greenhouse or can in the collection incubator, be provided with the heat accumulation built-in wardrobe when holding pouity dwelling place.Its radiating tube communicates with heat collector, the dragon pipe of cut-off footpath 28-40 millimeter also is drilled with several apertures of 2 millimeters, can realize solar radiation that every square metre of heat collector was collected 6 hours can make 5 cubic metres collection incubator temperature keep 15 ℃ for up to 60~70 hours.Because " multifuctional solar temperature collecting chamber " even have heat, cooling, heat accumulation, lagging facility be the shortest in " Winter Solstice " light application time, temperature still can be more than 80 ℃ in the collection incubator, spring and summer temperature in autumn can reach more than 200 ℃.
Application of the present invention will produce following good effect: 1, a kind of structure multiple use of a kind of profile.For example can be used as various high low temperature drying rooms, pitch heating, heating, culturing vegetable, hold pouity dwelling place raising etc.2, improve production capacity, because the volume of collection incubator can be according to using needs to decide.The desiccated wood one-period can reach tens meters, and the pitch heating can reach tens tons, and the pitch storage capacity can reach the hundreds of ton.3, temperature range wide (0 ℃~200 ℃) user can control temperature, humidity as required voluntarily.
Description of drawings:
Fig. 1: multifuctional solar temperature collecting chamber appearance structure schematic diagram
Fig. 2: multifuctional solar temperature collecting chamber internal construction schematic diagram
Fig. 3: collection incubator bottom surface underground structure schematic diagram
Fig. 4: the plate combination heat collector structural representation in parallel of serration type
Fig. 5: heat accumulation built-in wardrobe internal construction schematic diagram
Fig. 6: the double-deck transparency cover cover structure of collection incubator schematic diagram
Embodiment of the present utility model: collection incubator Fig. 1 of insulated building formula, due south, 1(orientation also can be by east or 10 degree to the west about) according to building engineering construction, volume determines as required, is 50 meters long, 12 meters wide, 5 meters high to the maximum.Four sides wall is the common brick structure, and intermediate course is inserted perlite (or glass wool or rock wool).Thermal insulation mortar is smeared in wall outside, in the wall apart from 1 meter on ground with top sticking reflecting material aluminum polyester Fig. 2 .16.Establish the control room at the Ji Wenxiangxi end, effective area is got 1/10th of collection incubator area, and structure is identical with the collection incubator.Loam cake is hidden when opening the door Fig. 1 .6 separately summer, reflective warming plate being opened, and interior temperature is not high, and warming is by two radiators of collection incubator quantity of heat given up band.The blower fan start stop switch, operating mechanisms such as water service pipe valve are located in the control room.Establish observation window Fig. 2 .13 of 600 * 700mm double-layer glass on the partitions of control room and collection incubator, in collection wall bottom, incubator north and south ventilation opening Fig. 2 .15 is set, the base of ventilation opening is lower than collection incubator ground so that draining.The quantity setting principle is that per 10 cubic metres of spaces are established one, and size is 200 * 200mm, makes of wooden frame.When not needing ventilating drainage, to stop up with 200 cubic millimeters foamed plastics, and the plate that sheet iron plate is made on wall outer end cap lid.Collection incubator bottom surface underground structure schematic diagram 3, ground is rubble-mound foundation 20, underground never frozen soil layer lower limit 21 will be higher than 2 meters of phreatic surfaces, on the never frozen soil layer pad more than 500 millimeters thick coal ash slag do insulation layer 22, smear one deck antiseepage cement 23 on it, do heat insulation layer 24 with one deck perlite then, ground is 200# steel concrete 25, peripheral shop, basis insulation layer is smeared into acclive waterproofing course and cement floor above.The framework of the transparent housing Fig. 1 of collection incubator .2 is with ∠ 50 * 5 angle steel construction drawings 2.18, with 12~14 yuan of steel Fig. 2 of the built-in fitting φ .19 welding on the four sides wall.Thermal insulation mortar Fig. 2 .17 is smeared in the housing surrounding, and the angle steel Fig. 6 .35 every a ∠ 50 * 4 of 0.8~1 meter welding in the middle of the housing framework does support, bores hole, φ 10 garden for 0.5 meter along angle steel length direction spacing.The rubber gasket 6.36 that adds 5 millimeters thick, two sides, hole, garden overlaps 6.37 with the glass of 6 millimeters of 3-on angle steel, leave 12 millimeters spaces between the glass of both sides, compacting flattens composes subgraph 6.38, between 12 millimeters space, pierce into M8 bolt Fig. 6 .42, fill up one deck rubber cushion above the glass again, pierce into 50 * 35mm flitch Fig. 6 .39 of a full light then, transparent flexible plastics Fig. 6 .40 of flitch upper berth one deck 0.5 millimeters thick, plastics on the housing are spliced into a monoblock with pressure sintering, and piece will be arranged on the flitch of support effect.Pierce into a flitch Fig. 6 .41 through satiety light and antiseptic 50 * 30mm above the plastics again, add bolt washer 6.43, fastening nut puts rubber cap Fig. 6 .44, the supporting-point when preventing from the bolt oxidation and doing reflective warming plate to close.Reflective warming plate Fig. 1 .3 thing north side three side gross areas are 2 times of collection incubator housing area, and single-block area is got 5 meters high 3 meters wide being advisable, and does framework with ∠ 40 * 4 angle steel, and burn-on 1 millimeter metal sheet of two sides is accepted sticking reflecting material aluminum polyester of sunlight.Preservative treatment is done at the back side.Insert light heat-insulating material glass silk flosssilk wadding between the doubling plate, the base of every reflector and side are pasted the elastic heat preserving material of 80 millimeters of wide 100 millimeters thick, the reflector lower end connects with collection incubator plane housing framework with folding, the upper end is welded with retainer ring Fig. 1 .8, connect with ground pre-buried retainer ring Fig. 1 .9 with backguy Fig. 1 .10, realize the change of reflective warming plate opening angle with the length of adjusting backguy.Absorber becomes zigzag Fig. 4 of drift angle 55 degree among heat collector Fig. 1 .4 with 1 millimeter pressing metal plates. and 27 fix with metal sheet lithograph 4.28 usefulness rivets, receive sunlight and simultaneously spray selectivity absorption black paint or plating, other structure manufacturing process is identical with common heat collector, and manufacturing finishes absorber must be through 2 * 10 4Pascal's pressure test.Heat collector can in parallelly as required make up, and every group of width can be 5~10 meters, and the gross area should equate with collection incubator housing area.During integral installation every group of heat collector is welded on stull ∠ 40 * 4 angle steel Fig. 4 .29 at the position up and down.Burn-on M8 bolt Fig. 4 .45 at angle steel two, upper end; pass the grooved hole of collection incubator south wall embedded part; fastening nut is as last fulcrum Fig. 3 .26 of heat collector; winter the heat collector lower end is placed Fig. 3 of A place (150# concrete for making) of ground support Fig. 1 .5; become 60 degree angles in ground line; place season in spring and autumn the B place to become miter angle, place summer the C place to become 30 degree angles.The one section cold pipe Fig. 4 of heat pipe Fig. 4 .30 .31 that heat collector communicates with collection incubator (or heat accumulation wall frame) all adopts bourdon tube so that heat collector is adjusted angle, heat pipe output and the input of cold pipe are all controlled with valve, directly import heat accumulation built-in wardrobe, direct input set incubator when not needing heat accumulation when needing heat accumulation.If temperature too high the two do not need and can import in the atmosphere.If the two needs to import Fig. 2 .11 simultaneously simultaneously, also parallel connection can be made up heat collector and be divided into two groups, one group is the heat supply of collection incubator, one group is the heat supply of heat accumulation built-in wardrobe.Heat accumulation built-in wardrobe Fig. 2 .14 is located at Ji Wenxiangnan within the walls.Volume size is relevant with heat collector area.The heat-storing cabinet that 1 square metre heat collector is configurable 0.2~0.3 cubic metre.Wall Fig. 5 .32 of cabinet makes 25 millimeters thick with 200# steel concrete, or does skeleton bag sheet iron plate with angle steel.Fill the marble chips stone 5.34 of 15 mm particle sizes in the cabinet, the nylon tube Fig. 5 .33 diameter that receives the heat collector heat supply can be 28~40 millimeters, and several apertures of 2 millimeters are bored in discharging twist on the tube wall.Hold by adorning solar water heater Fig. 1 .7 delivering hot water in the collection incubator in the heat collector west when needing to increase humidity in the collection incubator.The one section tube wall of hot-water line in the collection incubator is drilled to several water spray apertures Fig. 2 .12 multifuctional solar temperature collecting chamber and establishes a capital combination utilization simultaneously according to using the needs solar facilities to differ.

Claims (5)

1, multifuctional solar temperature collecting chamber belongs to the construction work that utilizes solar facilities.Contain solar energy basic equipment collection incubator, heat collector.It is characterized in that collection incubator, reflective warming plate and three kinds of equipment of heat collector are combined into one.Constitute major project by the insulation end, adiabatic wall, transparent housing--the collection incubator of insulated building formula.Collection is provided with in the incubator and heats, cooling, heat-storage heat-preserving facility; Thing both sides and north at collection incubator housing equal housing area 1-2 doubly by adorning the gross area.The reflective warming plate of adjustable angle; Serration type adjustable and that communicate with collection incubator and atmosphere plate combination heat collector in parallel in the elevation angle is installed in the wall outside, collection incubator south.
2, multifuctional solar as claimed in claim 1 temperature collecting chamber, it is characterized in that the azimuth that collects incubator can be about 10 degree by east or to the west of due south, four sides wall and ground are adiabatic heat-insulation formula structure, around the inwall overhead 1 meter with top brushing reflectorised paint or sticking reflecting material, can be provided with control room and heat accumulation built-in wardrobe in the collection incubator, wall is provided with ventilation opening, and last top is provided with the plane housing that the gradient 15% left and right sides light transmittance to the south is not less than 0.8 double-deck transparent insulation.
3, multifuctional solar as claimed in claim 1 temperature collecting chamber, it is characterized in that reflective warming plate makes framework with angle steel, welding two layers of thin metal sheet or edge paste wooden class plate or hard plastic board, are accepting the one side brushing reflectorised paint or the sticking reflecting material of sunlight, and preservative treatment is done at the back side.Insert light heat-insulating material between the two-ply, the lower end connects with collection incubator housing framework with folding, and the upper end is welded with retainer ring is adjusted reflector with the backguy length between change and ground retainer ring angle.
4, multifuctional solar as claimed in claim 1 temperature collecting chamber is characterized in that absorber in the heat collector is is the zigzag metal sheet surface brushing black paints of 55 degree by drift angle, is fixed on the plane bottom plate with rivet, can in parallel make up as required.
5, as claim 1,2 described multifuctional solar temperature collecting chamber, the outer wall that it is characterized in that the heat accumulation built-in wardrobe is made (or do skeleton bag sheet iron plate with angle steel) with armored concrete slab, rubbles such as the granite of thermal store usefulness 15mm granularity or marble are filled in the cabinet, the nylon tube that communicates with heat collector twist, and on tube wall, being drilled with several apertures of 2 millimeters, the nylon tube diameter is the 28-40 millimeter.
CN88221546U 1988-12-23 1988-12-23 Multi-function solar energy temp. collecting room Expired - Lifetime CN2044054U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN88221546U CN2044054U (en) 1988-12-23 1988-12-23 Multi-function solar energy temp. collecting room

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN88221546U CN2044054U (en) 1988-12-23 1988-12-23 Multi-function solar energy temp. collecting room

Publications (1)

Publication Number Publication Date
CN2044054U true CN2044054U (en) 1989-09-06

Family

ID=4853551

Family Applications (1)

Application Number Title Priority Date Filing Date
CN88221546U Expired - Lifetime CN2044054U (en) 1988-12-23 1988-12-23 Multi-function solar energy temp. collecting room

Country Status (1)

Country Link
CN (1) CN2044054U (en)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101149210B (en) * 2006-09-22 2010-09-01 黄金伦 Solar energy flat glass house novel structure
CN102353242A (en) * 2011-08-31 2012-02-15 中国科学院电工研究所 A flat-plate solar dryer based on heat conduction
CN102433967A (en) * 2011-09-08 2012-05-02 杨正国 Air compression type photo-thermal plate, photo-thermal glass tube and iron art keel technology
CN104089411A (en) * 2014-07-10 2014-10-08 北京聚能温室科技有限公司 Greenhouse solar energy anti-season heat storage and winter heating device and application method
CN106052145A (en) * 2010-07-05 2016-10-26 玻点太阳能有限公司 Concentrating solar power with glasshouses
CN108847141A (en) * 2018-06-29 2018-11-20 安徽天众电子科技有限公司 display device of L ED sign
CN109695909A (en) * 2017-10-20 2019-04-30 吴良柏 Across season high-efficiency solar storage heating heating refrigeration electricity generation system
CN110012749A (en) * 2018-01-09 2019-07-16 吴良柏 New plant growth controlled condition system and solar-heating heating refrigeration electricity generation system
CN110017252A (en) * 2018-01-09 2019-07-16 吴良柏 New type solar energy heat generating system
CN110068036A (en) * 2017-10-20 2019-07-30 吴良柏 Across season high-efficiency solar storage heating heating system
CN110272083A (en) * 2018-03-13 2019-09-24 吴良柏 Novel solar seawater desalination and water purification system
CN110268882A (en) * 2018-03-13 2019-09-24 吴良柏 Novel agricultural Greenhouse System and solar energy accumulation energy supplying system
CN110274294A (en) * 2018-03-13 2019-09-24 吴良柏 New type solar energy and air energy combined heat heating system
CN114246088A (en) * 2021-12-09 2022-03-29 周庆玉 Greenhouse container and working method

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101149210B (en) * 2006-09-22 2010-09-01 黄金伦 Solar energy flat glass house novel structure
CN106052145A (en) * 2010-07-05 2016-10-26 玻点太阳能有限公司 Concentrating solar power with glasshouses
CN106052145B (en) * 2010-07-05 2019-11-05 玻点太阳能有限公司 The concentration solar generating in greenhouse
CN102353242A (en) * 2011-08-31 2012-02-15 中国科学院电工研究所 A flat-plate solar dryer based on heat conduction
CN102353242B (en) * 2011-08-31 2014-01-08 中国科学院电工研究所 Flat plate type solar dryer based on heat conduction
CN102433967A (en) * 2011-09-08 2012-05-02 杨正国 Air compression type photo-thermal plate, photo-thermal glass tube and iron art keel technology
CN104089411A (en) * 2014-07-10 2014-10-08 北京聚能温室科技有限公司 Greenhouse solar energy anti-season heat storage and winter heating device and application method
CN104089411B (en) * 2014-07-10 2015-09-09 北京聚能温室科技有限公司 Greenhouse solar anti-season heat accumulation, heat supply in winter device and application process
CN109695909A (en) * 2017-10-20 2019-04-30 吴良柏 Across season high-efficiency solar storage heating heating refrigeration electricity generation system
CN110068036A (en) * 2017-10-20 2019-07-30 吴良柏 Across season high-efficiency solar storage heating heating system
CN110012749A (en) * 2018-01-09 2019-07-16 吴良柏 New plant growth controlled condition system and solar-heating heating refrigeration electricity generation system
CN110017252A (en) * 2018-01-09 2019-07-16 吴良柏 New type solar energy heat generating system
CN110272083A (en) * 2018-03-13 2019-09-24 吴良柏 Novel solar seawater desalination and water purification system
CN110268882A (en) * 2018-03-13 2019-09-24 吴良柏 Novel agricultural Greenhouse System and solar energy accumulation energy supplying system
CN110274294A (en) * 2018-03-13 2019-09-24 吴良柏 New type solar energy and air energy combined heat heating system
CN108847141A (en) * 2018-06-29 2018-11-20 安徽天众电子科技有限公司 display device of L ED sign
CN114246088A (en) * 2021-12-09 2022-03-29 周庆玉 Greenhouse container and working method

Similar Documents

Publication Publication Date Title
US8613170B2 (en) Solar roof tile with solar and photovoltaic production of hot water and electrical energy
CN104412047B (en) Insulating glass solar collector and buildings using it for heating and cooling with solar energy
US4054246A (en) Building structure for solar energy recovery and utilization
CN2044054U (en) Multi-function solar energy temp. collecting room
US20060124276A1 (en) Solar energy system
US4029081A (en) Solar energy transport system
CN110185292B (en) Industrial factory building venue and building method thereof
CN102200354A (en) Composite foam black ceramic solar heat accumulating plate and producing method as well as production applications thereof
CN201697381U (en) Composite foam black porcelain solar collector
US4338917A (en) Low temperature solar furnace and method
US4144999A (en) System and structure for conditioning air
CN203891495U (en) Solar heating structure of building
CN114484893A (en) Integrated solar heat collector
CN114482626A (en) New energy house
CN101344328B (en) Superconducting solar colored steel composite board heat collection device
CN101105052A (en) External wall thermal insulation decoration curtain wall with solar energy utilization unit
CN101603357B (en) Ceramic solar roof
US4353353A (en) Low temperature solar furnace and method
WO2007013115A1 (en) Element covering the roof and relative system capable of producing energy by solar radiation
JP3544529B2 (en) Solar thermal panels
WO2007045933A1 (en) Pergola solar collector system constructed from long heating elements
CN201031446Y (en) Solar reflection concentrating hollow light body insulation house
CN208901500U (en) A kind of workshop air displacer
CN102312497A (en) Solar and building integrated curtain wall system and installation and construction method thereof
CN201093767Y (en) Flat plate rain-proof type solar water heater

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C14 Grant of patent or utility model
GR01 Patent grant
C17 Cessation of patent right
CX01 Expiry of patent term