{"id":6339,"date":"2024-08-29T15:53:05","date_gmt":"2024-08-29T15:53:05","guid":{"rendered":"https:\/\/svestudy.com\/?page_id=6339"},"modified":"2025-05-12T19:21:34","modified_gmt":"2025-05-12T19:21:34","slug":"mde-unit-5-q5-answer","status":"publish","type":"page","link":"https:\/\/svestudy.com\/?page_id=6339","title":{"rendered":"MDE Unit 5 Q5 \u2013 Answer"},"content":{"rendered":"\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"237\" src=\"https:\/\/svestudy.com\/wp-content\/uploads\/2024\/08\/image-197-1024x237.png\" alt=\"\" class=\"wp-image-5913\" srcset=\"https:\/\/svestudy.com\/wp-content\/uploads\/2024\/08\/image-197-1024x237.png 1024w, https:\/\/svestudy.com\/wp-content\/uploads\/2024\/08\/image-197-300x69.png 300w, https:\/\/svestudy.com\/wp-content\/uploads\/2024\/08\/image-197-768x178.png 768w, https:\/\/svestudy.com\/wp-content\/uploads\/2024\/08\/image-197-1536x355.png 1536w, https:\/\/svestudy.com\/wp-content\/uploads\/2024\/08\/image-197-1200x277.png 1200w, https:\/\/svestudy.com\/wp-content\/uploads\/2024\/08\/image-197.png 1613w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Scroll Type Fuel Injection Pump:<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>(a) Varying Delivered Fuel Quantity:<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Unlike jerk-type pumps, scroll type pumps achieve fuel metering through a fundamentally different mechanism. Here&#8217;s how the delivered fuel quantity is varied:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"\"><strong>Scroll Design:<\/strong> The core of the pump is a spiral-shaped scroll housed within a cylindrical body.<\/li>\n\n\n\n<li class=\"\"><strong>Inner Rotor:<\/strong> An eccentrically positioned inner rotor with blades rotates within the scroll.<\/li>\n\n\n\n<li class=\"\"><strong>Fuel Chambers:<\/strong> As the rotor rotates, crescent-shaped cavities are formed between the rotor blades and the scroll wall, acting as fuel chambers.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Fuel Metering Principle:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li class=\"\"><strong>Fuel Intake:<\/strong> During rotation, the expanding volume of the fuel chambers on the suction side draws fuel in through an inlet port.<\/li>\n\n\n\n<li class=\"\"><strong>Fuel Trapping and Compression:<\/strong> As the rotor continues to rotate, the scroll&#8217;s shape progressively reduces the volume of the fuel chambers, trapping and compressing the fuel.<\/li>\n\n\n\n<li class=\"\"><strong>Delivery Valve and Outlet Port:<\/strong> A delivery valve is located at the outlet of the pump, connected to the high-pressure fuel line.<\/li>\n\n\n\n<li class=\"\"><strong>Fuel Delivery:<\/strong> When the pressure in a chamber exceeds the delivery valve&#8217;s opening pressure, the valve opens, allowing the high-pressure fuel to flow through the line to the injector.<\/li>\n\n\n\n<li class=\"\"><strong>Fuel Delivery Control:<\/strong> The amount of fuel delivered per cycle is primarily determined by the geometry of the scroll and the rotor. However, some designs might incorporate a bypass valve or variable control sleeve to influence the filling and discharge processes, allowing for limited adjustment of the delivered quantity.<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>(b) Purpose of the Delivery Valve:<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Similar to jerk-type pumps, the delivery valve in a scroll type pump serves a crucial purpose:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"\"><strong>Location:<\/strong> The delivery valve is positioned at the outlet of the pump, separating the high-pressure fuel section from the discharge line.<\/li>\n\n\n\n<li class=\"\"><strong>Function:<\/strong> The valve remains closed by a spring until the pressure within the pump chamber reaches a predetermined level.<\/li>\n\n\n\n<li class=\"\"><strong>Operation:<\/strong> As the trapped fuel gets compressed during rotor rotation, the pressure within the chamber builds up.<\/li>\n\n\n\n<li class=\"\"><strong>Opening and Injection:<\/strong> Once the pressure reaches the set limit, the delivery valve opens, allowing the high-pressure fuel to flow through the line towards the injectors for fuel injection.<\/li>\n\n\n\n<li class=\"\"><strong>Safety Function:<\/strong> The delivery valve acts as a safety mechanism by preventing excessive pressure buildup within the pump and fuel lines that could lead to component damage.<\/li>\n\n\n\n<li class=\"\"><strong>Closing and Cycle Repeat:<\/strong> After fuel injection occurs and the pressure drops below the set point, the delivery valve closes again, and the cycle repeats for the next injection event.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>(c) Preventing Fuel Spray in Case of High-Pressure Pipe Failure:<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Scroll type pumps typically incorporate a safety feature to prevent uncontrolled fuel spraying in case of a high-pressure pipe failure:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"\"><strong>Overflow Valve or Bypass Port:<\/strong> Some designs might use an overflow valve or bypass port located within the pump housing.<\/li>\n\n\n\n<li class=\"\"><strong>Operation:<\/strong> In case of a high-pressure pipe rupture, the sudden pressure drop would cause the overflow valve to open or fuel to bypass an internal passage.<\/li>\n\n\n\n<li class=\"\"><strong>Fuel Return:<\/strong> This allows the pressurized fuel to return back to the pump&#8217;s low-pressure side (suction side) through this overflow or bypass mechanism.<\/li>\n\n\n\n<li class=\"\"><strong>Preventing Spray:<\/strong> By redirecting the fuel back to the low-pressure side, the system prevents uncontrolled spraying of high-pressure fuel, minimizing the risk of fire or injury.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Additional Notes:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"\">Scroll type pumps are generally simpler in design compared to jerk-type pumps.<\/li>\n\n\n\n<li class=\"\">Their flow rate is typically less sensitive to variations in engine speed compared to jerk pumps.<\/li>\n\n\n\n<li class=\"\">However, their fuel metering capabilities might be less precise than those of jerk-type pumps.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Scroll Type Fuel Injection Pump: (a) Varying Delivered Fuel Quantity: Unlike jerk-type pumps, scroll type pumps achieve fuel metering through a fundamentally different mechanism. Here&#8217;s how the delivered fuel quantity is varied: Fuel Metering Principle: (b) Purpose of the Delivery Valve: Similar to jerk-type pumps, the delivery valve in a scroll type pump serves a [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"open","ping_status":"closed","template":"templates\/template-full-width.php","meta":{"nf_dc_page":"","footnotes":""},"class_list":["post-6339","page","type-page","status-publish","hentry"],"featured_image_src":null,"_links":{"self":[{"href":"https:\/\/svestudy.com\/index.php?rest_route=\/wp\/v2\/pages\/6339","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/svestudy.com\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/svestudy.com\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/svestudy.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/svestudy.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6339"}],"version-history":[{"count":1,"href":"https:\/\/svestudy.com\/index.php?rest_route=\/wp\/v2\/pages\/6339\/revisions"}],"predecessor-version":[{"id":6349,"href":"https:\/\/svestudy.com\/index.php?rest_route=\/wp\/v2\/pages\/6339\/revisions\/6349"}],"wp:attachment":[{"href":"https:\/\/svestudy.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6339"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}