JP2012506976A - Hydraulic tensioner for power transmission member having two operation modes - Google Patents

Abstract

  The present invention comprises a tube (7), in which a piston (5) connected to a second mounting member (11) is slidably connected, rigidly connected to a first mounting member (10), and a tube (7 ) And the piston (5) and is sealingly connected to the first and second mounting members (10) and (11) to define a low pressure chamber (21) of hydraulic fluid (15) ( 3), a prestressed main spring (1) between the first mounting member (10) and the second mounting member (11), and a low pressure formed in the first mounting member (10). A first channel (6 ′, 6 ″) that allows communication between the chamber (21) and the interior of the tube (7), the first channel at its end opening into the tube (7); A first channel (6 ′, 6 ″) provided with a gravity-sensitive blocking member (81, 83); (7) a second gravity-sensitive blocking member (82, 84) provided at one end of the second channel (5 ′, 5 ″) of the piston that is open to the inside, the channel (5 ′ 5 ″) is positioned in the piston (5) a high pressure chamber (20) positioned between the open ends of the first channel (6 ′, 6 ″) and the second channel (5 ′, 5 ″). A hydraulic linear tank comprising a second gravity-sensitive blocking member (82, 84) connected to the hydraulic fluid tank (22), the second blocking member being in the blocking position of the second channel when compressed by the tensioner Regarding tensioners.

Description

  The present invention relates to a hydraulic linear tensioner for a power transmission member having two modes of operation, in particular, but not exclusively, separated from an engine crankshaft and fitted with such a tensioner. The invention relates to a hydraulic linear tensioner for a reversible member capable of driving or driven a starter-alternator, and the present invention also relates to an engine drive system for a motor vehicle. A starter-alternator and a crankshaft which are fitted together by transmission pulleys connected to each other by a belt to be applied.

  The field of the invention is that of power transmission, more specifically, but not limited to, an engine of a motor vehicle, specifically a crankshaft and a starter interconnected by elastic links such as belts. The present invention relates to a reversible system for driving a motor vehicle engine with an alternator.

  The present invention can also be applied to any field that requires power transmission by a rotary machine or a rotary motor in an industrial facility, for example.

  It is known that the engine starter function is coupled into the engine alternator, and the coupled unit is referred to as a starter-alternator. This coupling makes it possible to dispense with separate starters, heavy toothed rings and electric starters coupled to a high inertia flywheel.

  The starter-alternator starts the engine via a flexible link, then drives the crankshaft pulley to act like a brake, and once the engine is started, the battery is recharged (alternator function). It functions as both drive members.

  The starter-alternator is coupled by being mounted directly on the crankshaft and is therefore sometimes referred to as an integrated starter-alternator (ISA) or separated (instead of a conventional alternator) and placed in a belt drive. Therefore, it may be referred to as a separate starter-alternator (SSA).

  An integrated solution (ISA) has been found to prevent good compatibility when installing / removing the system and, among other things, cause a rough and uncontrolled start.

  A separate solution (SSA) with a belt drive between the two parts, the crankshaft and the alternator, provides greater compatibility when installed and also provides a smoother start. The belt is of poly V type, cog type or trapezoid type. The invention belongs to this category when applied to starter-alternators.

  Engine start-up is a dynamic phenomenon that is rough and rapidly fluctuates as a function of internal friction, which fluctuates depending on the state of the connecting rods and the successive increases in compression.

  During such a start-up phase under high stress, the speed of the crankshaft increases rapidly and the crankshaft torque shifts from the driven state to the driven state. Under such conditions, the torque applied to the starter-alternator also varies from the driven state to the driven state.

  Under the so-called “started” state after starting, the crankshaft is driven and the starter-alternator is driven. In this mode of operation, the instantaneous speed of the crankshaft fluctuates approximately sinusoidally, and this phenomenon is referred to as engine acylism. Such speed fluctuations are transmitted to driven members such as an alternator (in this case, a starter-alternator operating in an alternator mode), a compressor, and a water pump by a belt.

  When a starter-alternator is used, since the moment of inertia is high, the generated dynamic torque exhibits a high amplitude in the start mode, and the rotation alternates between positive and negative even if the rotation is only in one direction. That is, these torques increase tensions from maximum tension levels and high stress on components (belts, member ball bearing tensioners or winders) to low minimum tensions that can lead to poor drive (slip) and noise. Fluctuate.

  The two operating modes may be defined as follows:

  A) In engine start mode, the torque to be generated by the starter-alternator to drive the crankshaft may reach a value of up to about 90 Newton meters (Nm). This is 180 N.m. (with a reduction ratio of 2 to 3). m to 270 N.m. It is possible to drive a crankshaft that exhibits an opposing torque in the range up to m.

  Conventional starters typically have a maximum of about 30 N.m. m drive torque, so that the starter can move onto the crankshaft with a maximum torque of 90 N.P. with a typical reduction ratio of 3 between these two members. m can be sent.

  When much larger torque than the conventional alternator needs to be sent to the crankshaft, the torque fluctuation is large, so that rattling causes fluctuations in the transmission through the belt and also causes the belt to slip. Become.

  Also, given the asymmetry of the damping effect (due to friction) and the mechanical asymmetry of the operation, the positive and negative torque values are not necessarily symmetric under both starting and starting conditions. It is also appropriate to observe

B) In the started mode, the torque to be sent is
-Dynamic torque generated by the inertia of the starter-alternator and by the accra rhythm of the engine;
-Combination with electrical torque required for power generation (alternator function).

  In the started mode, the torque to be transmitted is much smaller than in the start mode.

  Therefore, these two modes of operation are quite different.

The tensioner must be able to accommodate both modes by being manufactured to operate differently in these two modes as described below.
Fast response that can deliver a high level of torque in start mode while maintaining minimum tension sufficient to limit belt slip and ensuring engine start; and
• Limit the force in a started mode to a value sufficient to drive the peripheral without slipping the belt and overloading the belt and peripheral bearings.

  Conventional hydraulic tensioners do not allow both modes to be addressed simultaneously.

There are the following two categories that can be distinguished.
1) Systems that are neither controlled nor blocked These systems
Too little power is available to provide in start-up mode, as for example the device described in French patent application 2688565 (Hutchinson)
• The force provided in the triggered mode is too great, for example the device described in US Pat. No. 6,036,612 (NTN).
2) Tensioners that are controlled or have on / off blocking at start-up These tensioners are operated by a tensioner that is completely blocked during start-up, so this is for example PCT WO 02/29287 It operates like a fixed tensioner such as the tensioner described in the number (Gates) or by the pressure of a damping fluid that is externally controlled by an electrically controlled servo valve (eg, Ina-Schaeffler) In the name of PCT International Publication No. 2006/053617).

  Controlled tensioners are very complex and require external energy to be supplied in order to perform control functions. In addition, control logic needs to be implemented between the input signals (information regarding engine and / or peripheral speed and load) and the appropriate output signals (tensioner force / stroke).

  The object of the present invention is to overcome the above-mentioned drawbacks by an independent component that can be operated differently depending on the mode of operation, while not requiring energy to be delivered and requiring no external control. It is at least partly to avoid.

  The idea on which the invention is based is to incorporate a system with two shutter elements located in a common chamber inside a hydraulic linear tensioner, thus meeting the potential constraints associated with limited available space. Also make it possible.

Accordingly, the present invention provides a hydraulic linear tensioner for a power transmission member having a first operation mode with a large force and a second operation mode with a smaller force corresponding to a continuous operation. Is
First and second mounting elements respectively disposed at the axially opposite bottom end and top end;
A tube fixed to the first mounting element, in which a piston fixed to the second mounting element slides;
An elastic sleeve surrounding the tube and the piston, leak-proofly connected to the first and second mounting elements and defining a low pressure chamber for hydraulic fluid;
A main prestressing spring between the first and second mounting elements;
A first channel formed in the first mounting element for allowing the low pressure chamber and the inside of the tube to communicate, the first channel being responsive to gravity at its end that opens into the tube; A first channel provided with one shutter element;
A second shutter element that is responsive to gravity and is placed at one end that opens into the pipe of the second channel in the piston, said channel between the open ends of the first and second channels Interconnecting the high pressure chamber positioned and the hydraulic fluid reservoir positioned within the piston, the second shutter element is in a second position that is in a position to close the second channel when the tensioner is compressed. And a shutter element.

  The at least one shutter element may be a ball or a valve member (eg, a shutter washer that supports a seat) and its stroke may be limited by a stop device.

  The first and / or second shutter elements may present a return spring that drives these elements to the open position.

  The first attachment element may present a clamping element having a first end piece mounted thereon, the first end piece including the first channel.

  The first channel first communicates with the low pressure reservoir at at least one end and then communicates with at least one radial first channel that communicates with the axial first channel that opens to the first shutter element. May be included.

  A cylindrical sheath may be placed facing the radial first channel (s), thereby avoiding the formation of an air / oil emulsion.

  The second mounting element may present a clamping element on which the second end piece is mounted, the piston being mounted on the second end piece.

  The first and / or second end piece may include a collar cooperating with the cup, wherein one end of the elastic sleeve is received between the collar and the cup, and the collar and cup are elastic under the force of a spring. Pressed against the end of the sleeve.

  Since the end of the elastic sleeve is thus compressed between the collar and the cup, the tensioner is sealed from the outside at this level.

  Other features and advantages of the present invention will become more apparent from the following description given by way of non-limiting example and with reference to the drawings.

It is sectional drawing which shows the tensioner in the state which is not attached in suitable one Embodiment of this invention. The tensioner state when the engine is stopped is shown. The tensioner condition is shown while the engine is being started by its starter-alternator. Fig. 7 shows the tensioner in a relaxed state in the started mode. 6 shows a variant of the invention in which the upper shutter device is deflected by a spring.

  The tensioner whose longitudinal section is shown in FIG. 1 is for mounting in a vertical position (vertical axis ZZ ') or inclined at an angle of 40 ° to 45 ° or less.

  For example, the bottom mounting element 10 including the insert 13 that supports the smooth bearing 13 'is for mounting on the side of the engine, while the top mounting element 11 tensions the belt that connects the crankshaft pulley to the starter-alternator pulley. It presents a smooth bearing 11 'for receiving a hinge arm that supports the wheel used to apply the wheel.

  The tensioner has a spring 1 with a stiffness equal to, for example, 30 Newtons per millimeter (N / mm). When installed, the tensioner is pre-stressed to limit the installation stroke. Prestress is achieved by a clip 12 that forms a butt that prevents the tensioner piston 5 from moving up. Illustratively, the prestressing force is about 600 Newtons (N).

The soft sleeve 3, for example made of rubber, is attached in a leak-proof manner and defines the external contour of the low-pressure reservoir 21 containing the oil 15. The sleeve 3 is rigidly attached to the two end pieces 4 and 6 via its end collars 3 ₁ and 3 ₂ by seated cups 2 and 2 ′ which also rest on the plane of the collars 4 ₁ and 6 ₁ of the end pieces 4 and 6. Retained. The cups 2 and 2 'are held by pushing the collars 3 ₁ and 3 ₂ in the axial direction so that the collars 3 ₁ and 3 ₂ push the collars 4 ₁ and 6 ₁ by the compressive force of the spring 1 and thus provide sealing. Work.

  The female end piece 6 is rigidly fixed to the ball joint insert 13 by screws (not shown) passing through the ball joint insert 13 that supports the smooth bearing 10 and is axially clamped to the ball joint insert 13. . The male end piece 4 is connected to a ball joint insert 11 which is hingedly attached by a screw (not shown) passing through the ball joint insert 11 and is clamped axially on the ball joint insert 11.

  The tube 7 is rigidly connected to the female end piece 6. The female end piece 6 has at least one radial channel 6 'extending between the tube 7 and the sleeve 3 and in communication with a low pressure reservoir 21 closed at its axial end by the end pieces 4 and 6. An anti-emulsifying sheath 14 may be added in the oil passage between the two parts 7 and 3.

The female end piece 6 "is provided, the axial channel 6" axial channel 6, the seat 8 ₃ bottom ball ₈₁ is to have for example frustoconical shape resting with its own weight on it Open in. Ball _81, due to the cap 9 ₁ fixed to the female endpiece 6, the pressure defined by the upper end, a bottom end and a tube 7 of the piston 9 of and end piece 6 is positioned inside the tube Cannot escape from the chamber 20.

The piston 5 is rigidly connected to the male end piece 4. The piston 5 has at least one radial channel 5 ′ connecting the outside of the radial channel 5 ′ and the inside of the tube 7. A radial channel 5 'is accommodated in the tube 5 in order to return the non-emulsified oil to the axial channel 5 "by completely or partially emptying the reservoir 22 during expansion. Opening into the oil reservoir 22. In the example shown, the reservoir 22 forms an annular ring whose outer contour is closed by the tube 7. The axial channel 5 "in the piston 5 is the upper ball. for example for 8 ₂ provided and open to the frustoconical shape in which the seat 8 _4. Ball ₈₂ is positioned in the high pressure chamber 20, but can not escape due to the cap 9 ₂ fixed to the piston 5. Upper ball ₈₂ in its rest position, support the cap 9 ₂ under its own weight.

  Oil 15 can flow through high and low channels 5 ′, 5 ″ and 6 ′, 6 ″, high pressure chamber 20, low pressure chamber 21 and reservoir 22 in the manner described below.

  In a preferred example of the present invention, the piston 5 has a diameter of 12 millimeters (mm), the top and bottom balls have a diameter of 3.2 mm, and the axial top and bottom channels 5 "and 6" have a diameter of 2 mm. This sizing is described below, but it will be understood that the top and bottom elements may vary in size.

  The operation of the tensioner of FIG. 1 will be described below with reference to FIGS.

  In these figures, the tensioner is shown attached, and the piston 5 is moving down toward the female end piece 6 and removed from the prestressed abutment 12, thus tensioning the belt. ing.

The tensioner is generally delivered in a pre-installed position where the tensioner is in a minimum facing position. For mounting, the prestress is released and the tensioner occupies the position shown in FIG. In some variations, the tensioner may be manually compressed from the position of FIG. Oil, at a low speed, no difficulty passing through the shutter device _{8 1} and _{8 2.}

In the rest state shown in FIG. 2, bottom ball ₈₁ bears against the seat 8 _3, closes the oil passage. The upper ball 9 ₁ rests on the cap 9 ₂ by gravity, the oil passage is opened.

At start-up (FIG. 3), compression occurs in the tensioner (torque increase) and the piston 5 descends into the chamber 20 at a high speed. Upper ball ₈₂ closes the end of the channel 5 'which opens into the high pressure chamber 20 rises to the seat 8 _4, but during which the bottom ball ₈₁ remains pressed its seat 8 _3.

This causes the pressure to rise violently, resulting in a significant increase in the force required to tension the belt during start-up and prevent its slipping. During this start-up phase, it should be observed that the torque signal may alternate and the tensioner may also be in the relaxed position (see the relaxation mode described below). during the startup phase, the average moving speed of the tensioner, ensures that the upper ball ₈₂ continues remain in the closed position, and in particular the piston 5 and time leakage associated is of the same length in the gap between the tube 7 It has been discovered that it remains ultra-slow over a length of time sufficient to ensure that it occurs over time. This relatively long closure time, since the shutter device 8 ₁ and 8 ₂ are both in the closed position, it leads to a significant increase in force. This is the desired effect.

In the started state, large fluctuations in torque are smaller and the tensioner is simply stressed by dynamic fluctuations, some of which can be caused by engine acylism. Under such a state where stresses of small strokes alternate, the two shutter devices 8 ₁ and 8 ₂ operate alternately. These operations depend on the operation of the piston 5. The amplitude of the operation of the piston 5 under such conditions is about 1 mm to 5 mm, so that the reservoir 22 can be sized such that its capacity is greater than or equal to the amount of oil to be moved. Therefore, the following two situations can be distinguished.
A) compressing direction bottom closure device (ball ₈₁₎ is closed, the upper closure device (ball ₈₂₎ strikes its seating 8 ₄ rises, to stop the passage of fluid channel 5 '.

  Under normal operating conditions, there are two situations that can be distinguished.

a) an upper orifice (seat 8 ₄ of frustoconical _shape) (e.g., small, or due to very small Asaikurizumu) unobstructed completely by the upper device _82. Aperiodic acceleration is small, those sufficient to avoid a complete closure of the upper shutter device _82. A simple throttle effect is observed that gives the oil passing through the upper orifice the extra force required for operation in the started mode.

b) the upper device ₈₂ (e.g., a strong by Asaikurizumu) closed, alternates and closing the opening over a very short period of time the high frequency (Fig. 3). The pressure rise is reduced by the alternating frequency of the signal transitioning rapidly to decompression / expansion. Despite the occlusion, the force level remains much lower than the level reached in the starting mode.

Extreme conditions, i.e. under the predetermined state tension varies suddenly at the start and the mode (the verge of stall of the engine, events by blocking untimely peripheral equipment, etc.), the tensioner both shutter devices 8 ₁ and 8 ₂ By closing them completely, thereby generating a greater force to limit belt tension fluctuations.
B) Expansion direction , Fig. 4 (elongation)
While the piston 5 is moved in the direction of the arrow F ', the shutter device 8 ₁ and 8 ₂ are both in the open position.

Pumping effect releases the bottom orifice (seat 8 ₃ cone _truncated) by sucking the bottom shutter device _81, the upper shutter device ₈₂ releases the upper orifice 8 ₄ fall down. Opening of the shutter device ₈₁ is, to be supplemented with high pressure chamber 20 needs oil. This replenishment occurs from the channels 5 ″, 6 ″ and 6 ′ in the direction of the arrows F _{1 to} F ₃ and partially empties the reservoir 22. In order to maximize efficacy, the high pressure chamber 20 needs to be permanently filled with oil 15. The presence of air is extremely detrimental to the normal operation of the tensioner (accidental decay).

In two open state of the shutter device 8 ₁ and 8 ₂ while the piston 5 rises, the tensioner basically operates the stiffness of the spring 1 as the basis (the friction of the oil will be ignored), and the tension of the belt driving It should be observed that it is in its minimum state required.
Adaptation and possible adjustment adjustments are for use in the activated mode. As described above, the start is the mode, the upper device ₈₂ is closed too long to the compression direction between the bottom device ₈₁ is closed, it cause unnecessary force is too large Undesirable to become. In the triggered mode, it is possible to adapt the closing response of the upper device (8 ₂ , 8 ₄ ).

  For this, measures are taken against the inertia of the ball. There are two adjustable parameters available:

  a) Ball mass: This is basically a function of the ball diameter, since the material used is generally steel. To delay closure, the mass is increased and vice versa.

b) A closing stroke (between the rest position and the closing position) for generating a delay. This stroke is extended by acting on the position of the cap 9 _2.

Additional adjustment parameters, the upper closure device 8 _2, the return spring 30 to facilitate opening of the additional applied force and expansion direction that needs to be overcome in order to achieve the closed (see FIG. 5) It is to add. Although expensive, this may be appropriate if adjustment using the first two parameters is insufficient.
Bottom Adjustment : Improved Opening and Filling The bottom valve member may be modified, for example by adding a spring (not shown), so that it is normally open. Then, the closing of the bottom valve members 8 ₁ , 8 _{3 in} the tensioner compression direction is delayed by the force to be overcome prior to closing. Upper device ₈₂ may be closed thereafter.

The advantage of this device for adjustment acting on the bottom valve member appears in the relaxation direction. In the loosening direction, the spring may facilitate the opening of the bottom device _81. This can be devised as a pre-open that causes filling to occur more quickly.

Claims (11)

A hydraulic linear tensioner for a power transmission member having a first operation mode with a large force and a second operation mode with a smaller force corresponding to a continuous operation,
First and second attachment elements (10, 11) respectively arranged at the axially opposite bottom end and top end;
A tube (7) fixed to the first mounting element (10), wherein a piston (5) fixed to the second mounting element (11) slides therein; ,
A low pressure chamber surrounding the tube (7) and the piston (5), connected in a leak-proof manner to the first and second mounting elements (10, 11) and for a hydraulic fluid (15) ( 21) an elastic sleeve (3) defining;
A main prestressing spring (1) between the first and second mounting elements (10, 11);
First channels (6 ′, 6) formed in the first attachment element (10) to allow the low pressure chamber (21) and the interior of the tube (7) to communicate )), The first channel (6 ′, 6 ″) provided with a _first shutter (8 ₁ , 8 ₃ ) responsive to gravity at its end opening into said tube (7);
A second shutter element (8 ₂ , responsive to gravity and placed at one end of the second channel (5 ′, 5 ″) in the piston (5) that opens into the tube (7) 8 ₄ ), wherein the channel (5 ′, 5 ″) is positioned between the open ends of the first and second channels (6 ′ and 6 ″, 5 ′ and 5 ″) ) And a hydraulic fluid reservoir (22) positioned in the piston (5), the second shutter element being in a position for closing the second channel when the tensioner is compressed And a second shutter element (8 ₂ , 8 ₄ ) that may be present in the hydraulic linear tensioner. At least one shutter element (8 ₁ and 8 ₂₎ is characterized by having the ball tensioner of claim 1. At least one shutter element (8 ₁ and 8 ₂₎ it is characterized by having a valve member, tensioner of claim 1 or claim 2.   The tensioner according to claim 2 or 3, wherein a stroke of the ball or the valve member is limited by a butting portion. Wherein the first and / or second shutter element ₍₈₁ and / or ₈₂₎ is characterized by exhibiting a return spring to propel toward them to the open position, according to any of the claims above Tensioner.   Said first mounting element (10) presents a clamping element (13) having a first end piece (6) thereon, said first end piece being said first channel (6 ', 6 "). The tensioner according to any one of the preceding claims, characterized by comprising: Wherein the first channel is first at least one of said the communicating low pressure reservoir (21) at the end, then the first channel in the axial direction of opening to said first shutter element (8 ₁ and 8 ₃₎ (6 The tensioner according to claim 6, characterized in that it includes at least one first radial channel (6 ') in communication with ")". The first end piece (6) includes a first collar (6 ₁ ) cooperating with a first cup (2 ′), and the first end (3 ₁ ) of the elastic sleeve (3) is The first collar (6 ₁ ) and the first cup (2 ′) are accommodated between the first collar (6 ₁ ) and the first cup (2 ′). The tensioner according to claim 6 or 7, wherein the tensioner is pressed against the first end (3 ₁ ) of the elastic sleeve (3) by the force of 1).   Tensioner according to claim 8, characterized in that a cylindrical sheath (14) is arranged facing the first radial channel (6 ').   The second mounting element (11) presents a clamping element having a second end piece (4) thereon, and the piston (5) is mounted on the second mounting end piece (4) A tensioner according to any of the preceding claims, characterized in that The second end piece (4) includes a second collar (4 ₂ ) cooperating with a second cup (2), and the second end (3 ₂ ) of the elastic sleeve (3) is The second collar (4 ₂ ) and the second cup (2) are accommodated between the second collar (4 ₂ ) and the second cup (2) of the main spring (1). 11. The tensioner according to claim 10, characterized in that it is pressed against the second end (3 ₂ ) of the elastic sleeve by force.

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