The present invention concerns a hydraulic motor comprising a stator, a rotor concentrically disposed therein, said rotor comprising elongated slots which are provided with radially movable and freely rolling cylindrical action members, a valve plate, and possibly also an end plate on the opposite end, between said rotor and said stator being peripherally defined two or more chambers constituting working regions and between which are defined sealing regions. The valve plate comprises at both ends of the chamber, in peripheral direction, oil supply and exit apertures, which define a transition region between the sealing and working regions. The stator surfaces in the sealing region and in the working region which control/guide the action members are both shaped to be concentric, and the surfaces of the transition regions interposed between them are shaped to join them smoothly at their ends, whereby the action members are radially immovable in the working region and move in radial direction in said transition regions only. The valve plate comprises auxiliary supply passages separate from the main supply passages and disposed in register with the bottom of the rotor slots, for providing pressurized oil under the action members in order to seal these against the guiding surface.
The problem in motors of this type is caused by the pressure shocks due to unfavourable arrangement of the exit-side passages, said shocks resulting in jerky running, in particular at low speeds of rotation. The pressure shocks are due to sudden reduction of oil pressure on the exit side. The pressure shocks cause objectionable lowering of the mechanical efficiency.
The object of the invention is to disclose a hydraulic motor which is an improvement of hydraulic motors of the type described in US-A-2 725 013, presenting improved efficiency, a structural design which is orthodox from the viewpoint of flow technology, and smooth, jerk-free running at low speeds as well.
The hydraulic motor of the invention is characterized by that which is stated in the claim following below.
As taught by the invention, the supply passages are placed in peripheral direction on either side of the sealing region, and disposed to extend towards the working region through 12 to 25 degrees in a motor with two chambers, or through 5 to 12 degrees in a motor with three chambers, and to the purpose of ensuring the supply and exit of oil, and preventing the occurrence of pressure shocks, the margin of the stator adjacent to the valve plate comprises grooves at the supply/exit apertures extending, as seen in peripheral direction, over the entire transition region. Said grooves serve as relief grooves, causing gradual reduction of oil pressure in the transition region already, before the beginning of flow at full strength, and this precludes pressure shocks. Thanks to the gradually opening grooves, the pressure drop can thus become smoothly equalized without producing any pressure shock. On the other hand, the oil entering under the action members through the auxiliary supply passages disposed as taught by the invention makes the action members ascend immediately after the sealing region, thereby ensuring trouble-free operation of the motor. The hydraulic motor has, advantageously, at any time in the working region two rolling cylindrical action members sealed against the guiding surfaces, whereby excellent volumetric efficiency is achieved with the arrangement of the invention, since the quantity of bypass oil can be truly minimized.
The hydraulic motor of the invention runs without trouble and without pressure shocks, and it has high volumetric efficiency, as well as a compact and hydrodynamically favourable design.
The invention is described in detail in the following, referring to the attached drawing, wherein
In Fig. 1 is depicted a hydraulic motor, of which the principal components are: a rotor 2 mounted on a shaft 3, encircling it a cylindrical stator 1, and an end plate 4 and a valve plate 5, serving as ends for the chamber. The shaft 3 with rotor 2 is rotatably carried in the housing 8, which together with the rear shield 7 carries the stator as well as the end plate 4 and valve plate 5. The housing 8 comprises supply connectors 9, from which passages lead to the volumes P1 and P2, these volumes being partly confined by the valve plate 5. When pressurized oil is supplied to one of said two connectors, the valve plate directs the pressurized oil into the chamber between the stator 1 and the rotor 2, whereby the rotor is set in rotation by mediation of the action members, and the oil exits through the valve plate into the other of said volumes and, further, to the other supply connector.
In Fig. 2 is seen the arrangement of the rotor 2, and of the sleeve-like action members 6, within the stator 1. Here, the stator 1 comprises two opposed sealing regions 15 and two opposed working regions 19, which are constituted by concentric surfaces. Between them lie transition regions 18, which smoothly join the first-mentioned.
The rotor is provided with eight slots which are provided with cylindrical, sleeve-like action members 6. In bores made under the slots have been placed springs 10, which lift the action members by mediation of a pin 11. This enables a great number of action members to be used on the periphery without incurring problems of flow technology. The slots of the action members 6 are slightly flaring, whereby the pressurized oil has also access to the space under the roller in the working region 19.
Immediately after the sealing regions 15, at the transition region 18, supply and exit apertures 12 have been provided in the valve plate 5.
In addition to the supply/exit apertures 12, the valve plate 5 comprises auxiliary supply apertures 13, which are placed in register with the bottom of the slots in the rotor and which extend, in the present embodiment with two chambers, over about 18 degrees of the transition region, commencing immediately after the sealing region 15. Such auxiliary supply apertures are urgently required in view of the motor's operation. They are provided to ensure immediate lifting of the action members after the sealing region 15.
In the longitudinal section view of Fig. 3 can be seen a groove 17 provided in the margin of the stator 1; this groove helps to ensure the oil supply and exit and prevents pressure shocks from being generated. The groove 17 is positioned on the inside of the stator 1 in the region of the end margin, in register with the supply/exit aperture 12 in the valve plate 5, extending peripherally over the entire transition region 18, as can be seen in Fig. 2.
In Fig. 4 is shown the valve plate 5 of the motor of Fig. 2, this valve plate comprising four symmetrical supply/exit apertures 12 and four auxiliary supply apertures 13. They have been placed symmetrically at the transition regions 18 so that they commence immediately after the sealing region 15. The passages leading to the auxiliary supply apertures 13 are wider than the corresponding main supply passages 12, in order that the action members 6 could be lifted hydraulically out of their slots.