Inverted focalized transmission mount

A transmission mount has a mount base with first and second surfaces. The first surface has a transmission attachment point and the second surface has a vehicle attachment point. The second surface is opposite the first surface. The mount base also has first and second end portions angled towards a middle portion of the second surface. The middle portion is between the first and second end portions.

BACKGROUND OF INVENTION

The present invention relates to automotive transmissions and in particular to transmission mount assemblies for use in securing a transmission in an automotive vehicle.

An automotive transmission is part of a powertrain of an automotive vehicle and is supported in the vehicle on one or more transmission mount assemblies. Known focalized transmission mounts may have end portions angled inwards towards the transmission and away from an attachment point of the mount to the vehicle. The mount has an equivalent elastic center. As a consequence, the inward angled end portions define the equivalent elastic center above the mount.

The mount is secured to both the transmission and the vehicle and provides isolation to reduce noise, vibration, and harshness generated by the transmission. The noise, vibration, and harshness is reduced as a roll mode purity value for the powertrain increases.

SUMMARY OF INVENTION

An embodiment contemplates a transmission mount. A mount base has first and second surfaces. The first surface has a transmission attachment point and the second surface has a vehicle attachment point. The second surface is opposite the first surface. The mount base also has first and second end portions angled towards a middle portion of the second surface. The middle portion is between the first and second end portions.

Another embodiment contemplates a transmission mount. A mount base has first and second surfaces. The first surface has a transmission attachment point and the second surface has a vehicle attachment point. The second surface is opposite the first surface. The mount base also has first and second end portions angled towards a middle portion of the second surface. The middle portion is between the first and second end portions. A transmission is attached to the transmission attachment point.

Another embodiment contemplates a transmission mount. A mount base has first and second plates. The first plate has a transmission attachment point and the second plate has a vehicle attachment point. The second plate is opposite the first plate. Rubber pads support the first plate on the second plate. The mount base also has first and second end portions angled towards a middle portion of the second plate. The middle portion is between the first and second end portions. A transmission is bolted to the transmission attachment point. The angled end portions define an elastic center of the mount below the mount base.

An advantage of an embodiment is defining an equivalent elastic center, of a transmission mount, lower in a vehicle. The roll mode purity value increases as the elastic center of the mount is lowered. The angled end portions of the mount limit how far the elastic center may be lowered. The lower equivalent elastic center increases a roll mode purity value, which may reduce noise, vibration, and harshness.

DETAILED DESCRIPTION

FIG. 1illustrates an automotive powertrain, indicated generally at10. As illustrated, the powertrain10includes an engine12and a transmission14. The engine12and transmission14are coupled together such that the engine12supplies rotational torque to the transmission14. The powertrain10propels an automotive vehicle16. The powertrain10, engine12, transmission14, and vehicle16are merely exemplary and may take other forms known to those skilled in the art.

Also illustrated are an axis X in a fore/aft direction, an axis Y in a lateral direction, and an axis Z in a vertical direction. The powertrain10has three translation modes: a fore/aft translation18along the axis X, a lateral translation20along the axis Y, and a vertical translation22along the axis Z. Additionally, the powertrain10has three rotational modes: a roll rotation24about the axis X, a pitch rotation26about the axis Y, and a yaw rotation28about the axis Z.

FIG. 2illustrates a prior art transmission mount, indicated generally at100, having a mount base, indicated generally at102. The mount base102includes first and second plates104and106, respectively. The first plate104is supported on the second plate106by first and second rubber pads108and110, respectively, such that there is a separation112between the first and second plates104and106, respectively.

The mount base102is attached to the transmission14at first and second transmission attachment points114and116, respectively. The transmission14is attached to the mount base102using suitable means known to those skilled in the art. For example, the first and second attachment points114and116, respectively, may be bolted connections. The mount base102is also attached to the vehicle16at third and fourth vehicle attachment points118and120, respectively, using suitable means known to those skilled in the art. For example, the third and fourth connection points118and120, respectively, may be bolted connections.

The first and second plates104and106, respectively, are angled or bent towards the transmission14, and away from the vehicle16, at first and second planes122and124, respectively—i.e., the first and second plates104and106, respectively, angle upward as they extend out and away from a vehicle centerline X1. The first and second planes122and124, respectively, divide the mount base102into a first end portion, indicated generally at126, a middle portion, indicated generally at128, and a second end portion, indicated generally at130. The first and second end portions126and130, respectively, are angled towards the transmission14. The first and second planes122and124intersect above the mount base102. As a result of the first and second end portions126and130, respectively, being angled towards the transmission14, an equivalent elastic center132of the mount100is defined or located above the mount base102. A location of the elastic center132may be calculated using methods known to those skilled in the art.

FIGS. 3 and 4illustrate a transmission mount, indicated generally at200, having a mount base202. The mount base202includes substantially parallel first and second surfaces204and206, respectively, in the form of metal plates. The first and second surfaces204and206, respectively, are not limited to metal plates and may be fabricated from any suitable material and in any suitable shape. The first surface204is supported on the second surface206by first and second rubber pads208and210, respectively, such that there is a separation212between the first and second surfaces204and206, respectively. Alternatively, the first and second rubber pads208and210, respectively, may be fabricated from a material other than rubber that provides desired isolation or damping for the mount base202.

The mount base202is attached to the transmission14at first and second transmission attachment points214and216, respectively. The transmission14is attached to the mount base202using suitable means known to those skilled in the art. For example, the first and second attachment points214and216, respectively, may be bolted connections. The mount base202is also attached to the vehicle16at third and fourth vehicle attachment points218and220, respectively, using suitable means known to those skilled in the art. For example, the third and fourth attachment points218and220, respectively, may be bolted connections. The mount base202may be attached to a body, frame, or other suitable component or assembly of the vehicle16.

The mount base202has first and second planes222and224, respectively, that divide the mount base202into a first end portion, indicated generally at226, a middle portion, indicated generally at228, and a second end portion, indicated generally at230. The first and second surfaces204and206, respectively, are angled or bent towards the vehicle16, and away from the transmission14, at the first and second planes222and224, respectively—i.e., the first and second surfaces204and206, respectively, angle downward as they extend out and away from the vehicle centerline X2. In other words, the mount base202has the first and second end portions226and230, respectively, angled towards the middle portion228of the second surface206between the first and second end portions226and230, respectively. The first and second end portions226and230, respectively, are angled towards the vehicle16and the second surface206in the middle portion228. A first line234that is normal to the second surface206in the end portion226and a second line236that is normal to the second surface206in the second end portion230intersect below the mount base202at an intersection point238. Furthermore, the first and second planes222and224intersect below the mount base202.

As a result of the first and second end portions226and230, respectively, being angled towards the vehicle16, an equivalent elastic center232of the mount200is defined or located below the mount base202. A location of the elastic center132may be calculated using methods known to those skilled in the art.

Where the elastic center232is defined below the mount base202may be tuned or adjusted by changing how angled the first and second end portions226and230, respectively, are relative to the middle portion228. A first angle α extends from the first surface204in the first end portion226to the first surface204in the second end portion230and a second angle β extends from the second surface206in the first end portion226to second surface206in the second end portion230. The first angle α is greater than 180 degrees, the second angle β is less than 180 degrees, and together the first and second angles α and β, respectively, total 360 degrees. Alternatively, if the first and second surfaces204and206, respectively, are not parallel, the first and second angles α and β, respectively, may total more or less than 360 degrees.

The vertical position of the elastic center232may be adjusted on the axis Z by increasing or decreasing the second angle β. When the second angle β is decreased towards zero degrees, the elastic center232will be defined and located closer to the mount base202and transmission14. When the second angle β is increased towards 180 degrees, the elastic center232will be defined and located further below the mount base202. As the elastic center232is lowered, a roll mode purity value for the powertrain10will approach 100%.