Volvo Penta only uses liquid-cooled engines. The cooling system comprises a cooling water system and a cooling air system. The objective of the system is to lead heat from the engine to the surrounding atmosphere. Around 40 % of fuel energy is used to perform mechanical work, while the rest is lost as heat to the coolant and through the exhaust. The heat that is transferred to the coolant is 20-30 % of the fuel energy, and it must be carried away by the cooling system. The water pump forces coolant through the engine cooling ducts. Hot coolant enters the radiator, passes through pipes and is cooled by cooling air from the fan. In order to increase power and reduce exhaust emissions, a charge air cooler may be used. Volvo Penta uses two different types of charge air cooler. TWD engines have a water-to-air charge air cooler in which hot charge air is cooled by engine coolant. TAD engines use air-to-air charge air coolers in which charge air is cooled by cooling air from the fan. This type of charge air cooler is installed separately behind (or in front of) the regular radiator.
The cooling system must be dimensioned so that engine overheating is avoided during all ambient and operational conditions. It is therefore important to know the maximum air temperature and the environmental conditions where the engine will be used. Cooling requirements differ from engine to engine, and heat transfer to coolant is specified in the Sales
Support Tool, Partner Network for each engine. Additional to the heat transferred to the coolant from the engine, heat transfer from extra equipment, e.g. via the torque converter oil cooler, must also be taken into account when a cooling system is dimensioned. Cooling is also affected by obstacles to airflow and temperature increases above air-cooled accessories such as air conditioning condensers or air-cooled oil coolers. Air can also be heated by the engine and generator (generator set) before it passes through the radiator. In order for cooling to be as efficient as possible, it is important to minimize cooling air obstacles and prevent air recirculation by designing cooling air ducts and grilles correctly. Regarding the smaller VE series engines for which Volvo Penta does not provide a complete cooling assembly, all relevant data for the design of a correct cooling system is available under “Cooling system” and “Charge air cooling system” in the Sales Support Tool.
The function of the fan is to provide a cooling air flow. The fan creates a pressure increase that provides an air flow through the system components. Increased cooling air speed through the radiator core results in increased heat transfer from the fins to air. The air flow created by the fan depends largely on the pressure drop from components in the system. The fan is of axial flow type, but the air flow is not entirely axial. With an increase in installation pressure drop the air flow becomes more radial. The fan is usually belt driven, but on mobile applications certain engines also have crankshaft-mounted fans as an option. A crankshaft-mounted fan is exposed to higher stresses than a belt-driven fan. There are two main types of axial fans: fixed fans and temperature-controlled fans. The fan is an installation safety item and Volvo Penta fans are thoroughly tested before they are approved. Volvo Penta therefore recommends that only genuine Volvo Penta fans be used.
Fixed fans are used wherever large, continual cooling air flows are required. They are also used in installations where noise levels and fan power consumption are less important. Volvo Penta provides two different fan types: plastic fans and fans with aluminum blades that are riveted to twin steel hubs. Crankshaft-mounted fans must have rubber hubs to reduce vibrations from the crankshaft. There are two types of fan depending on the direction of airflow:
• Sucking fan (draws air in)
• Pusher fan
A sucking fan pulls cooling air through the radiator while a pusher fan blow air through the radiator. The following factors must be considered when determining the most suitable air flow direction for the installation:
1 The same fan diagram applies to two similar fans where only the air flow direction differs.
However, both pressure drop and cooling capacity are changed if air flow direction is changed on a given installation.
2 Wherever possible the air flow direction must be such that the air temperature at the radiator inlet is as low as possible (close to ambient temperature). This means that a sucking fan usually
provides the best cooling capacity. In the case of a pusher fan, air is heated by the engine before it passes through the radiator.
3 It is easier to achieve an even distribution of air flow over the radiator surface if a sucking fan is used instead of a pusher.
4 A pusher fan is usually required on gen set applications to ensure sufficient generator cooling.
5 On mobile applications with relatively high forward speeds air flow direction must be selected to draw benefit from the slipstream.
Temperature controlled fans
On temperature controlled fans, fan speed is controlled by engine temperature. The fan only runs when it is needed, which means that it uses less power and is quieter than a fixed fan. Silicone oil is used to transfer rotation to the fan via a rotating disc in a visco fan coupling (1), controlled electronically. Fan deployment is controlled by the coolant and charge air temperatures. The advantage with an electronically controlled fan is that the engine only need engage the fan when it is required and this saves fuel with varying loads. Note that the visco coupling must never be laid on its side
(e.g. when removing fan components), as the silicone oil will leak out. There is always a certain amount of slippage when the fan is engaged. The coupling must be designed for a given drive speed in order to function correctly. Volvo Penta uses couplings of viscous type for temperature controlled fans.
Fan plot (A)
The fan creates the greatest rise in pressure when it is working against a high back pressure, when it provides little air flow. The pressure increase across the fan reduces with higher air flows. The fan plot in figure 1 shows increases in static pressure in comparison to different air flow speeds (1, 2, and 3 in figure 1). There is a section on the fan plots with a epression called the stop zone (B). The fan is somewhat unstable in this zone and in realistic conditions the fan would work to the right of this zone; see figure 2. To the left of the stop zone the major part of the air flow from the fan is radial. Fan capacity plots issued by manufacturers usually refer to tests carried out in a tunnel test rig. The fan does not behave in the same way on an engine installation, but more like in a chamber test rig. The fan plots derived from the two different test methods are shown in the adjacent graph. The stop zone on engine installations is not as distinct and the fan plot is a little further to the right of the stop zone.
System plot (C)
Every air cooling installation has a given pressure drop for a given air flow. There is a point where the pressure increase across the fan coincides with the pressure drop across the installation at a given fan speed. This point in the fan graph is the working point at the actual fan speed. If the working points for different fan speeds are joined by a line the installation system plot is derived. See figure 3.
Air flow and pressure increases that a fan is able to create in a given installation are always determined by the fan plot and system plot intersection. The system plot can be expressed by the formula:
p = k x qA
p = increase in static pressure (Pa)
k = constant, dependent on installation
qA = air flow (m3/s)
The value k must be as low as possible for the installation, and is affected by all the components in the air cooling system. An installation with a small radiator surface area often has a high k value. The total cooling air pressure drop is around 2-3 times greater than the pressure drop across the radiator on uncovered generator set engine installations of types TD or TWD.
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Volvo Penta hutumia tu injini zenye baridi ya kioevu. Mfumo wa baridi inajumuisha mfumo wa maji ya baridi na mfumo wa hewa ya baridi. Kusudi la mfumo huo ni kuongoza joto kutoka kwa injini hadi angahewa linalozunguka. Karibu 40% ya nishati ya mafuta hutumiwa kufanya kazi ya mitambo, wakati wengine hupoteza joto kwa njia ya baridi na kupitia hewa ya kutolea nje. Joto linalohamishwa kwa baridi ni 20-30% ya nishati ya mafuta, na lazima kuendeshwa na mfumo wa baridi. Pampu ya maji husukuma maji ya baridi kupitia mifereji ya baridi ya injini. Mafuta ya baridi moto huingia kwenye radiator, hupita kupitia mabomba na hupunguzwa kwa hewa ya baridi kutoka kwa shabiki. Ili kuongeza nguvu na kupunguza uzalishaji wa gesi ya kutolea nje, baridi ya hewa ya malipo inaweza kutumika. Volvo Penta hutumia aina mbili tofauti za baridi ya hewa ya malipo. TWD injini ni pamoja na maji-kwa-hewa kuchaji hewa baridi ambayo joto kuchaji hewa ni baridi na injini baridi. TAD injini hutumia hewa-kwa-hewa malipo hewa coolers katika ambayo malipo hewa ni baridi na baridi hewa kutoka shabiki. Aina hii ya hewa ya kupumzika ni imewekwa tofauti nyuma (au mbele ya) radiator ya kawaida. Mfumo wa baridi lazima dimensioned hivyo kwamba injini overheating ni kuepukwa wakati wa hali zote za mazingira na uendeshaji. Kwa hiyo ni muhimu kujua kiwango cha juu cha joto la hewa na hali ya mazingira ambapo injini itatumika. Mahitaji ya baridi hutofautiana kutoka injini kwa injini, na uhamisho wa joto kwa baridi ni maalum katika Sales Support Tool, Mshirika wa Mtandao kwa kila injini. Kwa kuongezea joto lililopitishwa kwa baridi kutoka kwa injini, uhamisho wa joto kutoka kwa vifaa vya ziada, kwa mfano Kwa mfano, wakati wa kutengeneza mafuta ya torque converter, ni muhimu kuzingatia hali ya hewa ya hewa. Baridi pia huathiriwa na vikwazo kwa mtiririko wa hewa na kuongezeka kwa joto juu ya vifaa vya baridi ya hewa kama vile kondenseta za hali ya hewa au baridi za mafuta za baridi ya hewa. Hewa pia inaweza kupasha joto na injini na jenereta (genereta seti) kabla ya kupita kupitia radiator. Ili baridi iwe na ufanisi iwezekanavyo, ni muhimu kupunguza vizuizi vya hewa ya baridi na kuzuia mzunguko wa hewa kwa kubuni njia za baridi na grilles kwa usahihi. "Kuhusu injini ndogo za mfululizo wa ""V"" ambazo Volvo Penta haitoi seti kamili ya baridi, data zote muhimu kwa muundo wa mfumo sahihi wa baridi zinapatikana chini ya ""Mfumo wa Baridi"" na ""Mfumo wa Baridi ya Hewa ya Charge"" katika Chombo cha Msaada wa Uuzaji." Kazi ya shabiki ni kutoa mtiririko wa hewa baridi. mashabiki inajenga ongezeko la shinikizo ambayo hutoa mtiririko wa hewa kupitia vipengele vya mfumo. Kuongezeka kwa kasi ya hewa ya baridi kupitia kiini cha radiator husababisha kuongezeka kwa uhamisho wa joto kutoka kwa mabawa hadi hewa. Mtiririko wa hewa iliyoundwa na shabiki inategemea sana juu ya kushuka kwa shinikizo kutoka kwa vipengele katika mfumo. mashabiki ni ya aina axial mtiririko, lakini mtiririko wa hewa si kabisa axial. Pamoja na ongezeko la ufungaji shinikizo kushuka mtiririko wa hewa inakuwa zaidi radial. mashabiki ni kawaida ukanda kuendeshwa, lakini juu ya maombi ya simu baadhi ya injini pia kuwa crankshaft-mounted mashabiki kama chaguo. Kipaza sauti kilichowekwa kwenye crankshaft huathiriwa na mkazo mkubwa kuliko kichocheo kinachoendeshwa kwa mkanda. Kuna aina mbili kuu za mashabiki axial: mashabiki fasta na mashabiki joto kudhibitiwa. mashabiki ni kifaa usalama ufungaji na mashabiki Volvo Penta ni kikamilifu majaribio kabla ya wao ni kupitishwa. Kwa hiyo Volvo Penta inapendekeza kwamba tu halisi Volvo Penta mashabiki kutumika. mashabiki fasta ni kutumika popote kubwa, kuendelea baridi hewa mtiririko zinahitajika. Wao pia ni kutumika katika mitambo ambapo viwango vya kelele na matumizi ya nguvu ya shabiki ni chini ya muhimu. Volvo Penta hutoa aina mbili tofauti za mashabiki: mashabiki wa plastiki na mashabiki na blades alumini ambayo ni riveted kwa hubs mbili chuma. Crankshaft-mounted mashabiki lazima kuwa na hubs mpira kupunguza vibrations kutoka crankshaft. Kuna aina mbili za mashabiki kulingana na mwelekeo wa mtiririko wa hewa: mashabiki wa kunyonya (huchukua hewa ndani) mashabiki wa kushinikiza mashabiki wa kunyonya huvuta hewa ya baridi kupitia radiator wakati mashabiki wa kushinikiza hupuliza hewa kupitia radiator. Kwa sababu hii, ni muhimu kuzingatia mwelekeo wa mtiririko wa hewa katika mfumo wa uingizaji wa hewa, kwa mfano, kwa sababu ya kuunganisha viungo vya mtiririko wa hewa katika mfumo wa uingizaji wa hewa. Hata hivyo, wote kushuka kwa shinikizo na uwezo wa baridi ni iliyopita kama mwelekeo wa mtiririko wa hewa ni iliyopita juu ya kituo fulani. 2 Kila mahali iwezekanavyo, mwelekeo wa mtiririko wa hewa lazima uwe hivyo kwamba joto la hewa kwenye mlango wa radiator ni chini iwezekanavyo (karibu na joto la mazingira). Hii ina maana kwamba shabiki sucking kawaida hutoa uwezo bora baridi. Katika kesi ya shabiki pusher, hewa ni joto na injini kabla ya kupita kupitia radiator. Ni rahisi kufikia usawa wa usambazaji wa hewa juu ya radiator uso kama sucking shabiki ni kutumika badala ya pusher. 4 Pusher shabiki ni kawaida zinahitajika juu ya maombi ya seti ya jenereta kuhakikisha kutosha jenereta baridi. 5 Katika maombi ya simu na kasi ya juu ya mbele mwelekeo wa mtiririko wa hewa lazima kuchaguliwa ili kupata faida kutoka slipstream. mashabiki joto kudhibitiwa Kwenye mashabiki joto kudhibitiwa, kasi ya shabiki ni kudhibitiwa na joto injini. Kipaza sauti huendeshwa tu wakati inahitajika, ambayo inamaanisha kwamba hutumia nguvu kidogo na ni kimya zaidi kuliko kipepeo cha kudumu. Mafuta ya silicone hutumiwa kuhamisha mzunguko kwa shabiki kupitia diski inayozunguka katika kiunganishi cha shabiki wa visco, kudhibitiwa kwa elektroniki. Fan kupelekwa ni kudhibitiwa na baridi na malipo ya hewa joto. Faida ya fan ya umeme ni kwamba injini inahitaji tu kuunganisha fan wakati inahitajika na hii huokoa mafuta na mizigo tofauti. Kumbuka kwamba visco kuunganisha lazima kamwe kuweka juu ya upande wake (kwa mfano Wakati wa kuondoa sehemu za kipepeo, mafuta ya silicone yatatoka. Daima kuna kiasi fulani cha kuingizwa wakati shabiki ni kushiriki. Coupling lazima kubuniwa kwa ajili ya kasi ya kuendesha gari fulani ili kufanya kazi kwa usahihi. Volvo Penta hutumia viunganishi vya aina ya viscous kwa mashabiki wa joto kudhibitiwa. Fan plot: mashabiki huunda kuongezeka kwa shinikizo kubwa wakati inafanya kazi dhidi ya shinikizo la juu, wakati hutoa mtiririko mdogo wa hewa. Ongezeko la shinikizo katika shabiki hupungua na mtiririko wa hewa wa juu. Picha ya fan katika picha 1 inaonyesha ongezeko la shinikizo la static ikilinganishwa na kasi tofauti za mtiririko wa hewa (picha 1, 2 na 3). Kuna sehemu juu ya fan plots na epression aitwaye kuacha eneo (B). mashabiki ni kiasi fulani unstable katika eneo hili na katika hali ya kweli mashabiki kazi upande wa kulia wa eneo hili (tazama Picha 2). Upande wa kushoto wa eneo la kuacha sehemu kubwa ya mtiririko wa hewa kutoka shabiki ni radial. Fan uwezo plots iliyotolewa na wazalishaji kawaida rejea vipimo kufanyika katika handaki jaribio rig. mashabiki haina tabia katika njia hiyo hiyo juu ya ufungaji injini, lakini zaidi kama katika chumba mtihani rig. fan plots inayotokana na mbinu mbili tofauti za majaribio ni kuonyeshwa katika grafu jirani. Eneo la kuacha juu ya mitambo ya injini si kama tofauti na njama ya shabiki ni kidogo zaidi kulia ya eneo la kuacha. Mfumo plot (C) Kila hewa baridi ufungaji ina kuanguka shinikizo kwa ajili ya mtiririko wa hewa. Kuna uhakika ambapo kuongezeka kwa shinikizo katika shabiki huambatana na kushuka kwa shinikizo katika ufungaji kwa kasi ya shabiki iliyopewa. Hatua hii katika grafu shabiki ni hatua ya kazi katika kasi halisi shabiki. Kama pointi kazi kwa ajili ya kasi tofauti shabiki ni pamoja na mstari mfumo wa ufungaji plot ni inayotokana. Angalia picha ya 3. Mtiririko wa hewa na shinikizo kuongezeka kwamba shabiki ni uwezo wa kuunda katika ufungaji fulani ni daima kuamua na shabiki plot na mfumo plot makutano. "Kupima kwa njia ya ""k"" ni sawa na ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa ""k"" kwa "" kwa ""k"" kwa "" kwa "" "" kwa "" "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" kwa "" Usanidi na eneo dogo radiator uso mara nyingi ina thamani ya juu k. Kiwango cha chini cha joto cha joto ni mara mbili ya kiwango cha chini cha joto cha joto katika radiator ya injini ya injini ya aina ya TWD. Kwa habari zaidi ya Volvo Engine Workshop, tafadhali tembelea